Art 130 Reader
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Date Created: 08/22/13
Fall 2013 instructors Mills Hengler University of Hawaii at Manoa Art 130 Introduction to Glass Handbook MIEJEJS Glossary Section Subiectl Title Page 3 1 Joppa Glass Works Dudley Giberson an early how to instruction manual pp1ll for early studio glass days 2 Viscosity Graph Mills compares temperature heat color and uidity pp 12 3 Ray Flavell West Surrey college of Art and Design England drawing and discussions on creating basic glass shapes and vessel forms pp 1336 3A Glossary of Glass Terms pp 3745 4 Standard De nitions of Terms relating to Glass and Glass Products pp 4659 5 The Handbook of Glass Manufacture Scholes pp 6070 SA The Encyclopedia of Chemical Technology the chemistry of Glass Kirk Ottimer pp7179 6 Points of Interest Margi Jervis and Krasnican pp 8087 7 Decorative surface Treatments on glass F uming formulas pp 8891 8 Glass Technology Color in Glass Kerry Longaker pp 9293 9 Abrasive Blast Technique Dan F enton pp 94105 10 Cutting Straight Pieces of Glass Encyclopedia of Glass Working pp106120 11 Glass Adhesives and suppliers Henry Halem Glass Notes pp12l124 12G1ass History A Condensed Time Line Corning museum of Glass pp 125128 13 Suppliers of Glass Materials Tools etc Henry Halem Glass Notes pp 129152 14 Glass History Who Were the Glass Makers An Odyssey of the Jews pp l53 160 Sarnuel Kurinsky 15 An Illustrated History and Time line of Glass ppl61 179 nnllBau Il lu1IlCiIraY1ifPS LiLnntIr I In in i I x I Q I3939 i Dudley Giberson vIr 2 nl so u o 31 V S u nil T I T mLI l f w D I 1 Io aJvnwr 3 I 0 Inn u IRIxl 11 4 u o I II 1 o I I v an wwc I I u a 0 u I an 1 pr L1 1 J 1 tn 1 wwI A M4c Iu t u n u mire O 391 tan uflln J1 I IIrI k a nu aIl n 91 quot mmsxm J a14s J a us 1 u 1 0 4 I 3 Ilwtl rsuTwurp 3 NW nil in J uI 39 I SCHOOLS Boorrs M632ws 4 Toms E To 60 To 0 A 5 wIr1ER WIVquotD6396A 39 39 Gmv7 55 2 wears We ECK um W6 malnsx IS game ro 85 N9 1 PILCHUCK GLASS CENTER 80 34539E1JW fm Ey 2 FFNLAND 39 IO0L gPEVLAND MC 28 539 576 3 HAC ms I3911 R SCHooL f L 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responsible for glass West Surrey College of a Art and Design Fambam lt w Glass blowing still remains one of the most poorly documented crafm from the point of view of techniques This is perhaps because in the past there has been considerable mystique connected with it and as a result there has been little or no analytical study In this paper I hope to bring together some fundamental information on glass blowing techniques based on my own research as a craftsman designer and lecturer There is variation in approach to various details of glass forming in the different centres in Europe and these give rise to a number of characteristics of form which can be attributed to Italy Sweden and UK The differencm in working properties between flint mixed alkaline and full lead glasses also affect work procedure Here I am concerned with fundamental techniques which will 39 help to clarify some of the problems in glass forming by following established methods and how thme relate to studio gass where often the artist craftsman is I working on his own Modern technology has improved the quality of the glass melt through a greater understandirg of the glass maiting oxides and improved furnace refractories and through temperature control The tools used in the production of hand made glass remain uncharged and very simple The basic tools consist of E a blowing iron a hollow tube with coneshaped nose 42 to 60in 107 to 153cm in length b purity iron a solid iron onto which the halffornwd bubble an be transferred for further working French perm bridging tool c bit irons used for gathering smaller bits of glass for stems feet etc 42 to 60in 107 to 153cm in length paperweights wine stoppers etc These are used in conjunction with the chair which is a bench with two arms extending out from it on which the irons are rolled back and forth to create the rotational motion needed to form most blown glass shapes The marvcr a metal table on which the glass is rolled to chill and shape it The hand tools consist of a The spring tool with two flat bladm called the tools tongs puccllas or jacks b Wood jacks anothing sprirg tool with wooden pegs c Tweezers used for placirg the punty and striking the blowing iron when cracking off or pulling and shaping bits d Shears for trimming rims of blown pieces e Parrotnosed shears the end of which are designed to grip bit irons to position bits and V shaped blades to cut handles etc El 2 f Blocks for shaping and ehilliig the gather g Paddla for shaping h Pad of wet newspaper for shaping i The working hole or gory hole for reheating the piece in the process of making Not a tool in the normal seine of the word but vital part of the ptoctss Glam hlowitg has evolved over the past 2000 years and there is a greatidcaj of experience which one should analyse in order to appreciate the patterns and prooedura which form the basis of furnace melted and handmade glass My experience in teaching has shown that the novice will quickly tire of his failing initial attempts if there is not a basis on which he can hope to build his knowledge and experience The whole concept of glm blowing is so strange to quotthe uninitiated that the mans by which various shapes an be achieved need careful explanation so that the correct preparatory wocedure is undertaken Gathering ln the first instance the temperature of the metal molten pass should be related to the size and wdght of the nished piece lt is not possible to make a thin wineglass bowl if the metal is too cold and therefore too viscous equally if a large gather is required the metal needs to be more viscous The nose of the blowing iron should be heated to a dull ted temperature so that the metal will adhere to it A gather is achieved by introducing the very tip of the blowing iron into the rrmlt and rotating it rapidly with both hands insuring that it is resting on the iron pig a notched iron rest placed at the mouth of the furnace or at least the sill of the furnace pot or tank As the metal builds up on the nose of the iron it is then raised to a more horizontal position so that the gather is detached from the melt At his point the speed of rotation should only be sufficient to retain the gather centred on the nose of the iron Two major mistakes produce poor gthers namely a failing to make a clan gadter line by not rotating the iron in the same position or not making one complete revolution when it first enters the melt b when the desired weight 393 gathered allowing the final remnant to thread off at the side instead of the back causing unevenness Fig lab Either of these or a combination of the two produces a very uneven gather which is difficult to control and often leads to folding when tnarvering or blocking see below Folds become very chilled and muse an uneven section when blowitg When gathering metal in the higher temperature range soda or mixed alkaline glasses particularly for hits it is possible to increase the weight of the gather by traversing the surface of the melt to increase the build up on the tip of the iron already formed by rotation as in Fig2 F531 3 Block ing marvering and gathering weight The function of blocking or marveritg is to centre the metal on the iron to sham it and to chill the surface which provides a surface skin against which to blow The tools that serve this function are a tnarver from the French marbre marble these days a metal slab la wood blocks these have a hemispherical shape excavated from them and a handle They an be made from apple pear cherry beech or alder woods which produce a soft carbon layer and do not have a heavy grain pattern Beech am alder are particularly suited for moulds c paddle a flat piece of wood with a handle cut at one end used for shapitg on the chair d newspaper which is soaked in water and folded so that most of the water is squeezed out to form a stiff pad When used this will develop a soft carbon surfacc see Fig3 Sometinws paper is nailed onto the paddle Before describing the application of the above tools the process of controlling gathering weight needs some analysis As already stated the melt temperature should be related to the glasstnalter s needs and clearly if the melt temperature is higher then more stages of gathering will be required In additic to this full lead crystal is easier to gather than many of the other glasses from the point of view of its working properties though it is much heavier Fig4 shows a series of preparatory gathers increasing in size The pointed shape Ax represents the nal gather weigttprior to blocking and blowing Fg4a shows how the gather weight can be increased by first coating the nose of the iron by dipping it in the glass then allowing most of the metal to run back into the melt It should be noted that every am house has its own traditional rrwthod of working and that the above synem is intended to be a general guide The blocks are kept soaking in a bucket of water within easy reach ofthe worker39s chair When the gather has been made the iron is laid acres the arms of the chair and is then rotated and the block brought up underneath the gatha eonmct with the glass should only be made when the glen is rotating The gather must be kept centred by the action of rolling the iron so that the block is only shaping the gather too much pressure will push the gather off centre Care should be taken not to push the gather onto the iron Fig5 In Sweden the marver is only used for small gathers and the block is favoured more than the manner for shaping the gather Often they have blocks ranging from the smallest gather upwards Also the technique of blockirg differs from traditional Englhh glass houses in that the block is only used when the gather is being rolled away from the worker it is then tilted using the right arm of the chair as a fulcrum and drawn bad whilst the block is being rewetted This action maka the pther elongate rather than atten Fig6 Otherwise the iron is rolled backwards and forwards in the block rewettirg as necmary and often marveritg will he Fig 6 3 8 utilized to further shape the gther Many glas houses have a fixed iron block at the end of a large rnarver as in Fig7 The gather is first rotated in the block and is then rolled and pointed on the rnarver Carrying a large gather to the chair should be done with are insuring that the iron is held at the correct angle The gather mn very easily spread as in Fig8 and this an be avoided if the iron is kept in rotation but only sufficient to counteract the pull of gravity Success in many glass making techniques depends upon the glass worker nnderstanding of the temperature and viscosity of the metal A working rhythm which flows with the metal is Imential Fig 7 d Marvering The first gather is usually marvered as the chills the glass rapidly and gives rise to a nmt cylindrical shape which can be blown into a ball for subsequent gathering or a pariaon for smaller articla Fig9 in Sweden smaller marvers are preferred and used at a hTgher level and waxed so that the gather an be rotated in one position as well as heirg rolled from side to side Gther glam houses use a much larger matter at a bwer level and use the technique often alled whiting Figl0 F39 3 The first blow and zbe mrirmr quotThe next stage in the production of a piece 395 blowing up to form the parison the preparatory form in hot metal A useful example would be fortnirg a wine bowl off hand Workitg with moulds requires a slightly different approach and will be dmlt with separately The initial gather is made to the required weight Fig1 I This urill be either blocked or marvered and then shaped Figl2 The first blow will follow by introducing air rapidly into the hlowirg iron and smling it with the thumb This allows the blowing iron to be held horizontally and rotated as the bubble expands itself into the parison When the bubble has become the required size the thumb is removed from the end of the iron releasing the air pressirre Figl3 It is intereaing to note that the bubble always forms as a sphere within the molten mas and this should be visualized in relation to the external prepared shape This will determine the thins and thicks39 in the nal shape The action of blockingftnarvering will produce a thin skin of chilled gla which will inhibit the spherical shape of the bubble pushing further down into the hot glass Only experience can serve to control the behaviour of the prepared shape in relation to the bubble The inflated patison still hot enough to be easily shaped is now allowed to run out or stretch and this will give a thin section to the rirngof the finished glass The thin section is then cut down to between 15 and menu diameter This construction is then drawn out and cut again to produce a cracking off line Fig14 It is important that the initial cut should be made in thin glass and not in the chilled thick glass on the nose of the iron Fig1 5 shows the way in which a bubble forces its way through a layer of chilled gas on the iron before expanding Figl6a shows a good shape for cracking off also the slightly strengthened section at the end is less likely to crack from thermal shock when teheating if the parison is only cut in without being necked slightly the resulting shape is likely to cause cracking into the bow FigI6b Once the tooling at the pipe has been completed this part of the parison should not be touched apin with the cold tools until it is ready for cracking off at which point the tools can cut on the colder glass which will be sufficient to make a clean circular crack It should not be necessary to use water when the glass is as light as this in section P3l6 a Li An altanatite method of ZW PHP 0 T swim bowl 75 often allcd op blow RN psrison is wepared by cutting oww was the iron before the bubble is blown As the bubble expands into the metal it antomatimlly thkxs out when the cut was made The is allowed to run out and the ersampi off line pepued as before Fig17 Having established the cracking off line and also the approximate width on the bowl the remaining thicker section an at this point he further shaped In some instances the thicker section at the base of the bowl will have tetairwd its hm whilst the top will have set up It is then pmible to blow the shape further without d tortiI the top However it 395 often necessary to rebut the lower pert of the bowl taking are not to dhtort the tap again Figl8 shows how the shape can he elongated without further tooling F gl9 shows other tooled shews Other typical shapes Baring in mind the methods of inerusing gathcrixg weight other shew like decanters or bottluean be formed by using altermtive methods 13 Fig20 illustrates the stop blow usedquot on a decanter Fig2 illustrates the same shape by gathering and blowing on a bubble or ball F ig22 shows how the neck can be formed on the first gather and the body of the piece gathered onto it This produces a gather line characteristic of many German and Scandinavian bottles and decanters Rehcatilg the parison should be kept to the minimum pardcuiatly when it has a thin section The piece is but formed ivithout rehating and therefore retaining the blowformirg characteristics This means the effect of havig an inner andan outer chilled surface between which the hot metal an ow in a controlled way Softening the outside skin muses thin glass to pocket and in so doing creates hot and cold spots which then blow oat unevenly when the prison is blown again when working on the blowing iron there is always a great temptation to blow quotinto the hot metal in order to inaease its size This normally results in a wide shape which tends to become too thin in the bottom Greater volume an be achieved by usilg the ductile property of the metal in letting it run out and then blowing the elotgated form and shaping it with the wood Tpcks if necusary 13 39b 1 Fig 23 E5 The term hammade for glamnaking is 3 d ficult one for the Iayrmn and can cause scum misunderstanding for craftsmen when it comes to moulds But as a general rule glass is handmade if it has been gathered and prepared by hand on E a blowing iron or gathering iron prior to its being mould formed To work with moulds for glassmaking requires a great deal of craft skill 39 which perhaps is not always appreciated became the term mam repetition and Kg mass production 539 TI 24 E I I E E I 8 5 5 5 E 5 E 3 1 n gt I I Lu J 2 i g I 5 9 A 3 1 OZ Rotational or turn round moulds Though traditionally made of cast iron because of its durability on long runs graphite and wood moulds are used in glass house production Experimentation F with other materials for studio work is offering a wider choice Mould desgn There are two determining factors which apply to shapes made in moulds If the piece is going to be finished by machine then the mould will be exactly the shape required plus allowance for cracking off see Fig33 If the piece is going to be handfinished on a punty then allowance should be made in the shape for 39 reheating and further shapiig Fig2 shows a handfinished beer mug and a I machine finished one The handfinished piece therefore needs to he tapered at the top so that it can be shared to size and then opened to the required diarmter The normal rule for mould design is true for gm there can be no undercuts Fig24 shows romtional mould configurations Wooden moulds are kept soaked in water and form their own soft carbon layer which in conjunction with steam gives a polished surface to the glass Wooden moulds are best with an open bottom which is grooved to let out the stain Cast iron moulds require paste which consists of varnish linseed oil with wood floor or cork dust which gives a carbon layer NB There are many recipes for mould paste but generally layers of the above materials or similar are used The paste has to be baked onto the mould approx 80 C for 4ltO 8 hours and then it has to be worked in to give a final finish to the surface Graphite moulds need a paste for rotational tnotilds All moulds need to be sprayed or immersed 4 uI uIo in water after every forming and some glass houses use soapy water to aid the wetting The moulds should be suitably vented to let surplus steam escape The skill in working with moulds is in the preparation of the parison which should be as near to the mould shape as possible in order to take up the shape of the mould with the correct distribution of weight or section 139 IZ 18 0n the Continent moulds tend to ovetblow out of the mould Fig2 Sal 39 otherwise the ovetblow is accommodated in the mould Fig25b Gathering 390 3 ball is common practice when working with moulds particularly when working of1ilIsBxa ii6ather is marvered and blown out then cut down on the nose of the iron Thcgsecond gather is made about threequarters of the way round the ball as in F7g26a and is then blocked The patison is further in ated and shaped with a stiff wad of newspaper as in Fig27 This technique is used in Sweden and enables glass to be formed very thinly both for mould and offhand work An interesting observation here is that one is always blowing into a parison of a pointed shape Fig28 Whether it is shaped on the matver with paper or 8 paddle this always produces thin sides and a thicker Fig26b shows the same sequence but without being cut down and gathered up to the original line on the iron This enables more glass to be gathered but has so be cut down after it has been in the mould for cracking off Series Zea is 39 better for pieea going straight in the iehr a because the bail is usefulan keeping the patison open at the top and b bemuse it breaks cleanly from the Iron on the original cut in Series 26b is more useful where the piece is going to be hand finished on a punty because a the glass would be thicker and b have no gather line to shear through Fig2 shows a typiml gather line Fig 2 F53 W 18 Fig 30 7 6 when the parison has been in ated it should be retained in a short condensed shape until it is allowed to stretch vertically into the proportions of the mould Fig3O 39 If the mould is bottie shaped then the parison will have to be shaped on the chair with the tools to make a neck form as it stretches into the mouid Difficulty is often experienced when cutting down glass which 395 very hot because there is a tendency for it to corkscrew The answer is that a hot parison will curve as it is rotated in balance on the chair Fig1 and this mans that Fig 31 3922 21 tools must be angled to accommodate this Also the torgs should be deflected over as in Fig32 If the mould had a wide at base then it is useful to tap the patison at on a pad at the side of the mould Fig33 Sometimes fixed blocks of different parison shapes are used see Fig34 Fig35 is an example of a marvcted parison in glass houses working with large moulds the traditional chair is not used instead the glassmakcr stands and rolls the iron in a fixed position and does not use hand tools other than a block A typical exampie is shown in Fig36 This technique is used in handmade lighting ghss in Engiand Germany and Sweden F33 35 S2 9 9 5Cr c otg off This is the prmm of rernoviw the wane glss from the top of a blown PICCC an alternative to hand nhhing on the purity iron A line is scratched round the gas at the desired cracking off point and then a fine flame is playecloti this 39untii thermal sho causes a crack to occur on the line Fig37a This lam E sharp edge which can be either polished Fig37b 0 3m0 0h d with 3 continuous abrasive belt Fig37c finally being polished with pumice powder on s cork wheel Fig37e Fig37f shows three typical seetiom of glam edge nishing Still moulds These can be any shape that can be relatedito the process of blowing on an iron and can have intricate surface detail which will reproduce in the glass Still moulds do not require paste as the glass will reproduce the surface agaimt which it is blown Wood is not ideally suited to this process because it will quickly burn Best results are obtained from cast iron moulds hated to between 400 and 500 C Graphite can be used satisfactorily 9 The mould design can accommodate many pieces to produce complex shams but idmlly should be closed at the top so that a reasonable pressure of blow can be achieved to take up mould details Fig38 The glassmaket usually salt the air with his thumb over the month end of the blowirg iron in a similar way to rotational moulds s polishing effectan be achieved on shapes that have a regular crosssection This 393 achieved by s reciproating action see Fig39 Wooden moulds give a good surface and can be simple in section or might be complex sections excavated with chisels etc Fig 33 AZ In addition to the above a mould an R anything which will inhibit the formation of a round bubble in gass and could he a simple structure as in Fig40 Optic moulds and dip 3110 adds These are pre ntoulds which form an optical mttern through the section of the glass Fig4 shows two typical moulds 533 ll Puntying All the processes discussed hitherto have been related to the blowing iron so here we an look at the second stage of the handmade prooew that of workirg on the pnnty iron The punty is a device which facilitates the finishing off of the open end of the blown piece This is achieved by gathering a small bit from the furnace and attaching it to the centre of the base of the piece This is a temporary attachment and therefore should only be sufficient to sustain the weight of a glass piece being nished Often the purity is crossed see Fig42 to minimize the point contact dipping the punty in sand or chalk also helps to minimize adhesion If the piece has been well blown and has the correct section and is centred on the iron then the finishing process seerm effortlws If the piece is not well prepared then it is V91 difficult to control After reheating and slightly opening the rim of the piece it is sheared When rehntirg the rim are should be taken not to overheat the punty musing the glas to droop off centre when laid acrow the arms of the chair Sheariig is effected when the iron is rolled away from the glsnmaker He holds the shims in the same position whilst feediiw the glass through F ig43 The blades of the shears should never be allowed to close fully and as the glass 73 cut it should he pulled slightly and slid open on the forward stroke This action should be rapid and rhythmic No attempt should he made to shut a piece that is too cold hecaum the cot may not go all the way round and tiny chips of glm y on to the inside of the piece and stick there Also if sharing is anticipated then the diarneta should be kept small at the open end It is impossible to shear round a wide and thin piece If a very hmvy section of glass is to be shared then care should be taken to but the section thoroughly at the 92 2397 sen time ensuring that the hat is loalized by opping down the working hole Let the outside surface of the gins chill a little before sharing so that the shuts do not bind and have the effect of sealizg the surface of the glass together Fig44 The sheared edge is now reheated and then opemd out web the tools A common error here is chatter mused by letting the tools sprirg own in the middle of the openirg and an be oorrected by lifting the tools tightly about the centre Some glass blowers prefer to go below centre P If the openirg is larger than the tool natural spring then a liftiq action is used to incrnse the size as in Fig45 Wood jacks should be used on wider openirw The tools chill the glans very quickly and therefore the stretching and openirg shoukl be a positive and quick action Rehearing and rotating rapidly on the chair will are out the shape further if dwired and care should be taken so the piece is inserted to the daired depth of the glwy hole A dqree of further Fig 45 92 shaping is possible on the purity but the blown parison should be earefuily arrarged to provide most of the basic form Wanting or foldirg can be achieved as in Fig46 A thin neck on a decorative piece can be made as in Fig4397 For decanters the forming of the neck on the blowing iron is less likely to create problems of distortion if the piece is reheated only at the end of the neck Fg48 29 Bowls disbes and plates This is part of the glassmaking process where the reheating whilst on the punty is as important to understand as working with hand tools Much of the work can be done in the glory hole Fig49 shows how a cylindrical shape can become a vase or plate by the amount of reheating The form is achieved by rapid spinning which throws the hot section out Ideally the parison needs to be fairly thick at the open end in order to aid the centrifugal force Offhand bowl shapes can be very subtle forms but often the mistake is made of trying to force an illconsidered parison into an open bow shape After shearing and rehuting the piece the wood jacks shonid be used to open up from the inside After this initial opening the piece is best opened from the outside either with the wood jacks or a large paddle as in Fig50 Fig 49 39LZ 30 quotif the piece is hot enough then centrifugal force will be pushing out against the tools a much more satisfactory arrangement than forcing cooler glass outward from the inside against the ductility of the glass which would be the only resistance lnvariably this forces the piece off centre or stretches the sides unevenly Plates require a speci cally shaped parison as in Fig5 When it has been shared and reheated the paddle should be used to keep the rim turning in and chilled allowing the body to spread The final reheating followed by rapid spinning should make the rim install to form a disc which can be shamd from the back with a paddle workhag wkh bits Steam and feet on wine glasses The traditional means of addirg bits for sternware fall into two categories casting on and sharing on the former being practised mostly in the UK Casting an The glass worker prepares the wine bowl and positions it on the arm of the chair as in Fig52 H39s assistant gathers the bit which he scores with the tools as in FigS3 then whilst he rotates he angles the blowirg iron then allows the gather to run off the bit iron and settle centrally on the bowl Then he swiftly thrusts the latter away breaking the hot metal where it was originally scored FigS4 The execution of this technique requires gent coordination of hand and eye in order to place the bit centrally and avoid threading F53 53 31 quot32 The Continental glass houses tend to adopt the shearirg on technique shown in Fig55 fkrc the bit gatheret holds the iron wh le the maker stcadies it with his shears and places it on the piece and then makes two angled cuts Another variation used in UK for iarger bits is for the maker to hold the bit iron himself and shear on the bit while his assistant holds the blowing iron vertically Fig56 bZ 3 SbapEng tube stem In the same way as the new gther has to be marvered or blocked to chill the surface of the sing the bit has to be both centred and chilled and this can be achieved either by usirg the flattened spring part of the tools or a small steel ddle Steel paddles must be waxed or the glm will stick to them The bit is cut down to the required diameter at the bowl and then the bladm of the tools are allowed to open sfghtly The tools an deflected outwards the blades ending slightly open on top of the stem chilling the glam further to produce a straight stem as in Fig57 The bowl of the glass should be thick enougi at the base to retain some heat If the stem bit is placed on too cold a mo it will chill it too much at the joint and muse difficulty in mum down From the basic cylindrial stem a variety of sham can R tookd A straight cut will produce a convex curve and an anged cut will woduee a concave curve FigS8 Similar tooling can be lived for stoppers and knok Special bronze or graphite diet are used in most glass houses to nmke new shape for wine suites etc Fig59 A yeater variety of form can be achieved in stem by adding snaller bits Fig60 Blown additiom an be placed in stems built up in this way the bubble prepared on 3 xcond iron Fig6 The connecting be in these stems n mlled a tnerae39 1 1 35 30 if the ductile property of glass is to be used to produce thinner stems then the bit should be chilled by the tools at those points which are intended to remain thicker Fig62 For a straw stem only the tip should be tapped lightly to produce the ball to pull out into the stem Fig63 For thcsc Stcms thc mttal needs to be hot so that it chills on the wine bowl to form a neat rounded bit which needs no centrixg Small bits of hot metal form a surface skin of chilled 339 glam as the cold air paw over them and like any fluid will try to form a sphere Care should be taken when pulling out the stem because if the glau is too hot it may suddenly eomtrict in one place Fig64 Foot making This is achieved by squeezing and rotatiig the bit havirg been either st or sheared on between two small boards hinged together Fig65 There are a number of variations on this too but the principle is the same in all cam Difficulty in spinning out the foot can be ensued by glass sticking in the tool instmd of running smoothly The tool must be well soaked in water but not too wet on the surface as this will OVtlquotClIlll giving rise to an elliptical foot Fig66 shows that if the foot is awied slightly the glass will ow without jamming the diagram is exaggetated to show what happcts As soon as the disk is formed then the foot board should be removed so that a the glass does not burn the foot boards and b the glm does not beconw too chilled to shape further F53 65 l F53 5 38 Blown foot A small bubble is prepared on the blowixg iron am placed on the stem in the manner of a punty Fig67 This an be welted or folded at its edge Fig68 A further development of the blown foot is to make a pointed pnrkon which foam the stem and foot this is often used in Sweden Fig69 F33 69 quotCE Bits added for decoration The ltalian tradition of glasntaking has utilized added bits in the form of threading a continuous spiral of glass wunting bits which have been prmscd with a small mould in the manner of a seal and pinching squeezing added bits between textured dies of a spring tool The placing of a handle is also a technique of manipulating a bit The handle should be mannered into a cylindrical shape taking care not to make it too cold The bit iron is then held with the parrotnosed shuts and pressed well down cnto the body of the glass and then pulled up and sheared The bit should still be hot enough to elongate slghtly when hung down When it is swung up the shut mark should be placed on the glm and pressed under Fig70 1 Blowing out bits Hot bits can be further blown out on thin glass to form spouts etc The bit is shared on the cooler parison and is blown sealing with the thumb This will moduce Ian in ated bulge if this is then pulled with the tweezers or parrotnosed shears a spout is fomwd as in Fig7l Fig 72 ES 42 Steam stick and co mpressed air Air bubbla can E made in the glass without the blowing iron A large gather is made and blocked A pointed piece of metal is pushed into the gass This is then in ated by the formation of steam from the pointed end of a piece of wood which has been kept soaking in water Alternatively orw can use a burst of compressed air from a nozzle Fig72 Tbe studio glassworker The above information is intended to present basic methods and clearly there is not space here to cover every known detail hopefully it is enough to give a reasonable picture of what is possible in traditional glass housm No reference has been made to colour techniques There are numerous ways of addirg colour to glass in the hot process This can cause problems in forming by changes in viscosity between one colour and another Certainly colour in glam is being rediscovered and newly discovered in the studio and workshop and preoccupation with colour is a major part of studio work The problem for the artist craftsman workirg on his own is devising methods which enable him to work by himself when one considers that the handmade chair or 39casterole chair in the factory glass house is composed of a team of at least five giassworkers the footblower who gathers the glass and blocks of rnarvers the servitor who blows the form and adds hits the workman who takes it on the punty shears and shapes the open end the bit yther stems feet and handles etc and the boy who takes the piece to the lehr clearly the individual worker has to compromise on some standard work procedures This compromise has proved to be an innovatory one and many interesting ways and means have been evolved by artist craftsmen in the last decade in solving problems of puntying and working with bits I have deliberately attempted to identify standard traditional methods in this pawr as a platform on which to build new patterns and procedures for the artist craftsman and as a documentation for those interested in glass design It is for the individual to decide how this information can be applied to his specific needs It is indeed vital to note that excellence in the aesthetic sense cannot refer only to glass which is awless and perfect in its execution By not usirg standard procedures of control glass work can take on forms which enhance its unique properties of ductility and ii lli refraction therefore it can be a vehicle for free expression For most artist craftsmen making yam pieces puntying is the first problem This is usually done by layirg the blowing iron across the chair and then gatherirg a bit which is then marvered before being centred on the base of the piece this then being rolled along the arms of the chair to make any corrections necessary The risk here is that the piece will be rather cold if it is going to hold 3 its shape while the purity is being wcpamd and therefore timirw is critics Another method is to use a Vshaped wooden box into which the piece is cracked the purity is then stuck on centre Any correction can then be made This method is often used on handmade chairs in some factories The piece is finished in the normal way Stem bits A number of glam artists here in the UK have become very moficient at mating on Fig73 The blowirg iron is turned with the left hand against a stop on the arm of the chair and at the same time a second gather is run on to the wine bowl with the right hand The glass maker then sits on the chair and continues with normal tooling to shape the stem Another technique employs the shearing on method by clipping the blowing iron to the right arm of the chair and then shearing on the bit Fig74 3977 q u can be left on a motorised rolicr at the end of the chair this device will keep th hut parison centred Discs of hot metal cast on the marvcr providc a useful means of adding bits for further working Working by oncscif docs present problems of speed of making The glam has tu bc rchcatcd rather man than quot 5 6 Designing for the handmade industry The word desgrf these days can be grossly misunderstood and therefore I wish to clarify the matting its relation to the glass industry By designing l refer to the plan made by a manufacturer to make products or srtefacts This definition would place the glen designer in a key position in the day today running and developrmnt of a glass factory Many glass manufacturers throughout Europe have become well known as a result of their forwarddooking dwigrr policies but unhnppily there are many who see the role of the designer as a minor one Dmiguing glassware in the past has been an evolutionary process derived from human weed and unit skill with technical knowledge Many glass designers are still at the mercy of someone else39s interpretation of their ideas and often the old mystique is left totally in the hands of gassmakers who perhaps justifiably cannot identify with ideas which might stretch their capability beyond the traditions handed down to them Designing glass is only successful where a policy which allows for design development to take place Hopefully more designers in future will have firsthand experience in worltirg the material which will he a true ertwession of the medium and not merely a graphic representation handed to the workmen The designer nevertheless should always be aware that it remains a commerchl activity and that awarenex of market requirements should make particular demands on the products he es designing ftesented at WORKING WlTH HOT GLASS an lnternatiottal Conference organised by the Crafts Advisory Committee and Royal College of Art London September 1976 3992 abraded decoration A type of decoration executed by shallow grinding on a Wheel as a speedier and less exacting process than facet engraving and With designs in curved lines circles and ovals acidetching Decoration on the surface of glass by the use of hydro uoric acid varying from a satin matt nish to a deeper rough effect The process involves covering the glass with an acidresistant wax varnish or drying linseed oil and then scratching the design With a sharp tool A mixture of hydro uoric acid with potassium uoride and water is then applied to etch the exposed design into the body of the piece The depth of etching varies with the time of exposure of the glass to the acid The acid must then be thoroughly washed off since it is highly corrosive agate glass A type of decorative opaque glass made by mixing several colours usually purple and green before shaping a glass object so as to imitate natural semiprecious stones such as agate chalce dony onyx malachite lapis lazuli and jasper airtwists Spiral veins of air formed by the extension by blowing of tears in stems of drinking vessels and ornamental wares alkali A soluble salt one of the essential ingredients in making glass being about 15 20 per cent of the batch It serves as a flux to reduce the fusion point of the silica annealing 1 The process of reintroducing a completed object into an auxiliary part of the glass furnace like a lehr in order to cool it slowly This results in the release of any strain created in the glass during the forming process 2 In the manufacture of painted glass windows the techni que of attaching pieces of coloured and shaped glass to a larger piece of clear glass by using solder glass eg as jewels around the edge of a garment antique glass A hand rnade Window glass which has the uneven rearny appearance of medieval glass at thefire The process of reheating a blown glass object at the glory hole during manufacture to permit further blowing to enlarge it or alter its shape or to permit manipulation with tools 39 at theflame at thelamp lampworking The tech nique of shaping glassware from rods and tubes of readily fusible glass by heating and thus softening them at the flame originally of anoil lamp later of a gas burner The glass is then manipulated to the required shape aventurine glass A type of translucent glass flecked throughout With sparkling oxidized metallic partin cles simulating the appearance of brownish aventurine quartz which is flecked with mica or other minerals baluster A term used to describe a type of drinking glass with a baluster stern made in England bar See cane barilla Soda from calcined plants native to Spain backpainting See lairzterglasmczlerei bczsse taille A subdivision of Cmmplev enamel in which a design in low relief chased or engraved on a base plate is covered with a transparent layer of enamel The modelled surface is visible and graduations in the height of the relief are reflected by variations in the depth of colour in the enamel batch The mixture of raw materials generally silica soda and lime heated together in a crucible or pot to make glass Broken glass caller and minor ingredients such as colourants may also be added to the batch 275 37 276 Glossary block A block of wood hollowed out to form a spherical recess After being dipped in water to prevent charring it was used to form a blob of molten glass into a sphere as an initial operation in making a globular paraison blow pipe blow iron The hollow iron tube used to take a gaztlaer of molten glass from the pot and then to shape it by blowing the mass paraison into a bubble The tube usually up to 175m long and about 250 mm in diameter has a thickened end for gathering the glass metal and sometimes wooden coverings where the workmen must handle it The metal end is heated before use to cause the gathering of glass to adhere bottle glass green glass A common naturally coloured dark greenish or brownish glass The colour is characteristic of unre ned glass including traces of iron found in the natural silica used as an ingredient Sometimes additional quantities of iron in the form of iron oxide were added to darken the colour Used for making bottles broad glass See cylinder glass bull s eye pane See crotem glass cage cups See oasa diatreta calcar calker caulker A type of retzerlweratory famace used for calcination of the batch into frit cames Strips of lead used as an integral part of glass windows cameo glass cased glass An object formed of cased glass of two colours such as opaque white that forms an overlay on coloured glass where the outer layer was carved on a wheel so as to leave a design in white relief on the coloured background with the effect depending upon the extent and depth to which the white was removed See ashing cane rod bar A slender rod of glass groups of which are bundled together and fused to form a polychrome design The bundle is heated and drawn out to achieve the required 39 diameter Multiple inlays or appliqu s can be sliced from each bar each retaining the identical design cartoon The full scale design for a painted glass window Early examples were drawn on whitened boards or on a plaster floor tracing oor At a later date paper or parchment rolls were used Cartoons were often adapted for designing several different patterns and bequeathed from one glass painter to his successor cased glass See cameo glass cast glass A type of glass made either by 1 fusing powdered glass in a one or twopiece mould ie open vessels or solid objects but not hollow vessels or 2 by the are perdae process chair 1 The bench used by a gaffer while forming a glass object It is a wide bench with flat extended and slightly sloping arms The gaffer rests the l9low pipe with its paraison of molten glass on the arms and constantly rolls it back and forth so that the paraison keeps its symmetrical shape and does not collapse during manipulation The French term is laanc a laardelles 2 The team which assists the gaffer sometimes also called the shop It usually includes five to six craftsmen and apprentices cbampletz enamel A technique in which areas of the metal base are gouged out and the hollows lled with vitreous enamel leaving a raised metal outline cire perdae The lost wax process originally used in casting bronze pieces and later for glassware A model was carved in wax then encased in a mould Heat was then applied to cause the wax to melt and run out after which the mould was lled with molten glass or reheated powdered glass Cire perclae was used for pieces too detailed to be effectively produced by the usual process of making in a mould clippings See slaearirzgs cloisorm enamel A technique in which differently coloured vitreous enamels are separated by narrow cloisons or strips of metal which have been soldered on to the metal base cold colours Lacquer colours or oil paint applied as a decoration to glassware as to porcelain without ring Often much of this type of decoration has worn off antique pieces Such colours are more effectively used when applied to the back of the surface to be viewed and protected by a layer of varnish or metal foil or by another sheet of glass cold cutting The process of cutting a glass vessel or object from a raw block of glass which has not previously been cast to shape The cutting is carried out by means of a rotating wheel fed with water coloured glass Glass that is coloured by 1 impurities in the basic ingredients in the batch or 2 techniques of colouring transparent clear glass by three main processes a by use of a metallic oxide in solution in the batch to impart a colour throughout b by use of a substance in a colloidal state or c by use of embedded particles of coloured material combed decoration A wavy festooned feathery or zig zag pattern of decoration in two or more colours which was produced on glass objects by applying threads of opaque glass of a different colour to that of the molten glass body The threads were rolled into the glass body by maroering after which they would be combed or dragged to achieve the desired effect composition See Egyptian faience cord See reamy glass core forrning The technique of forming a vessel by trailing molten glass over a core supported by a 38 metal rod or dipping the core into the molten glass The object was removed from the rod and annealed after which the core was scraped out cristallo A type of soda glass developed in Venice perhaps before the fteenth century It was made with sea plant ashes or natron and had a pale yellow straw like or smokeygrey colour By the use of manganese as a decolorizing agent the glass was made colourless and thus resembled rock crystal crizzling crisselling A basic defect in the glass caused by an imperfect proportion of the ingre dients in the batch particularly an excess of alkali resulting in a ne network of cracks and the formation of moisture on the surface Such glass if incorrectly stored eventually decomposes and crumbles crown glass buIl seye pane Normandy mode Flat glass made by the process of blowing a bubble of glass transferring it from the blowpipe to a rod cutting it open then rapidly rotating it with repeated reheatings until by centrifugal force the glass spread into a large flat disk up to 12m in diameter The glass was then annealed and cut into rectangular or diamond shaped pieces that were fairly thin but showed slight convexity and concentric wavy lines caused by rotating leaving the centre boss or bull s eye where the rod had been attached cullet Cleansed and broken glass from glass objects discarded during manufacture and remnants moil left on the bow pipe or the pontil melted together with the fresh ingredients of a new batch cutline In painted glass window design the tracing of the lead line pattern from the cartoon cylinder glass broad glass muff glass Flat glass made by the process of blowing a large glass bubble and swinging it on the blotspipe to form a long bottle Both hemispherical ends were then cut off the resultant cylinder muff up to 15m in length was then cut lengthwise with shears and reheated after which it was attened using a wooden plane or by being allowed to sink to a flat state Cylinder glass showed straight ripples and retained less polish than crown glass The quotprocess was called the Lorraine method because it had been used in Lorraine France as early as circa 1100 decolorizing agent A mineral e g manganese oxide used to counteract in glass the dark greenish or brownish colour resulting from iron particles in the silica sand ingredient or imparted to the batch by iron or other impurities in the pot or elsewhere in the production process The decolorizing agent does not remove the colour but acts as a chromatic neutralizer it and the iron absorbing the light that the other transmits if in equal quantity if too Glossary much of both is present little light can be transmitted and the resultant glass if thick becomes grey or blackish devitri cation The process of converting glass into a crystalline substance by heating the glass to a temperature just below its Ziqaidas temperature Under these conditions part of the glass forms a definite crystal compound having an opaque appearance diamondpoint engraving The technique of decorat ing glass by engraving using a diamond point to scratch the surface S dichromatic glass Glass showing different colours depending on the angle of light falling on it as when seen by reflected or transmitted light This is sometimes due to the addition to the bate of a tiny percentage of colloidal gold e g the Lycurgus Cup appears red by transmitted light and olive green by reflected light dividing iron A medieval tool used in the manufac ture of painted glass windows the tip of which was heated to crack pieces of glass glomis A style of decorating glass by applying gold leaf occasionally silver leaf or both and then engraving it with a ne needle point Since such work was un redit would readily rub off It was therefore usually applied on the reverse of the surface to be viewed and then protected by a layer of varnish or metal foil or another sheet of glass Sometimes there is a supplementary background decoration in black or colour where the foil has been removed i Egyptian blue A blue pigment in which the colour is due to a copper calcium silicate a synthetic form of the mineral cuprorivarite CaOCuO4SiO3 CaCuSi4O0 Silica is usually present in excess Egyptian blue may be ground and used directly as a pigment or moulded into objects and re red Egyptian faience faience composition A red silica body containing very small amounts of clay andor alkali and varying greatly in hardness depending on the degree of sintering It is covered with a glaze which may or may not occur interstitially to the silica grains of the body The term glassy faience is often used to describe a faience in which the degree of melting has proceeded to such an extent that the glass phase de nes the visual appearance of the material The term unglazed faience is used to describe a similar body also produced by the sintering or partial vitri cation of silica particles probably with a fluxing agent andor colourant added Glass may be a minor component There is no clearly de ned glass layer The term frit is a common synonym for this material 4 278 Glossary enamel colours Enamel colours are metallic oxides mixed with a glassy frit of finely powderedglass and suspended in an oily medium for ease of application with a brush The medium burned out during ring in a low temperature muffle kiln about 500 700 C Sometimes several rings were required to x different colours enamels See lvasse taille claamplev enamel Cloisonne enamel painted enamels engraving The process of decorating glass by cutting the design into the surface of the glass by a diamond metal needle or other sharp implement or a rotating wheel There were various techniques diamondpoint engraving t22laeelengrat2ing stip pling Related processes are etching and sand blasting etching See acid etching eye 1 The centre of the siege of the glass furnace the hottest part 2 The hole occhio in the floor of a lelar through which heat is transmitted 3 The coloured tip pearl on the pmnts of some Nuppenbecher and other fteenth or sixteenth century Antwerp and German glassware fagron ale Venise 21 la In the style of Venice as applied to high quality glassware made throughout Europe often by emigrant Venetian glassworkers especially the thin soda glass and glassware decorated in ligrana or with ornate embellish ments such as winged glasses It was developed in the mid sixteenth century and ourished through out the seventeenth century faience See Egyptian faience ferramenta See glazing liar filigrana tretro filigranato Literally thread grained A term that has been applied to glassware with various styles of decoration of clear glass made originally at Murano Italy circa 152749 by the use of opaque white or coloured glass threads or even occasionally a single white thread However it is now usually used to refer to all styles of decoration on clear glass that are made with a pattern formed by embedded threads of glass fireclay Clay capable of being subjected to a high temperature without fusing and hence used for making crucibles in which early glass batches were fused The clay contains much silica and only small amounts of lime iron and alkali fire polish The brilliant surface condition given to glass by heating at the mouth of the furnace glory hole after the manufacture of a glass object The process removes the dull surface sometimes irn parted to glass by the mould firing The process of heating the bare in order to fuse it into glass by exposing it to the required degree of heat in a crucible or pot or of reheating un nished glassware while it is being worked or of reheating glassware in order to fix enamel colours or gilaling The melting of the batch may require a temperature of 1300 1500 C and the muffle kiln a temperature of 500 700 C ashing The gathering of a small amount of one glass on a much larger gather of a different glass For example dense copper ruby glasses were flashed on clear glass in order to dilute the effect of their colour Flashed glass formed into vessels could have the outer layers cut back to form cameo designs flint glass 1 A misnomer for English lead glass probably arising as a result of the evolution of lead glass at a time when calcined or ground int was substituted for Venetian pebbles as the source of silica for making the glass Later sand replaced the flint but the name flint glass has persisted and is still sometimes used to refer to all English lead glass 2 In the glass container industry flint bottles are those which are colourless 3 In the optical glass industry flint glasses are those which have a smaller refractive index for the same dispersion than crown glass flux A substance added to enamel colours so as to lower their fusion point during ring to below that of the glass body to which they are to be applied A flux was also added to the bare in order to facilitate the fusing of the silica Fluxes include potash and soda founding Modern initial phase of heating the laatcla in the furnace when the materials must be heated to a temperature of about 1400 C before a maturing period of 12 hours during which the molten glass cools to a working temperature of about 1100 C Ancient glasses had to be fritted before they could be melted freeblown glass offhand blown Glassware shaped solely by the process of blowing with the use of a lalotirpipe and shaped by manipulation with the tools of the craft as opposed to mouldl9lown frigger Glass objects of various forms made by glassmakers in their own time for their own amusement and home decoration or for sale They were usually made from the molten glass remaining in the port at the end of the day considered as the workrnen s perquisite frit The granular product of the first stage of ancient glass or glazemaking the raw materials are heated to temperatures around 850 C to produce solid state reactions between them When cool the frit is ground and melted to produce a homogeneous material fritting The preheating of raw materials to initiate glassmaking reactions and drive off volatile reaction products The result is a granular material 40 or frit When the frit is ground and reheated it melts more readily than original batch materials gaffer The master worker of the team chair or shop engaged in making glass objects The gaffer does the most skilled and intricate work and controls the procedure of the team until the object is completed and sent to the leor for annealing gathering A blob of molten glass attached to the end of a gathering iron blowpipe or porztil preparatory to forming a glass object gilding The process of decorating glassware on the surface or on the back of the glass by the use of gold leaf gold paint or gold dust The gilding may be applied with a size amalgamated with mercury fired or un red glass A silicate material that has been substantially molten during manufacture and has been cooled in such a way to remain predominantly non crystalline It may include unrnelted batch mate rials devitri cation products and intentionally produced opaci ers It can be formed into an in nite number of selfsupporting forms and shapes glass forming The heating and reshaping of a piece of lass gl ss rnaking fritting The preparation of the glass batch from its basic raw materials glass melting The preparation of molten glass by melting down fragments of caller and frit glass metal The fused vitreous material in quota molten state made up of various ingredients eg silica and alkali from which glass objects are made The metal produces glasses of varying characteristics depending on the quality and proportions of the ingredients The term is regarded as archaic by glass technologists glass oflead See lead glass glassmakers tools The various instruments used by a glass n1aking team chair to develop and shape an object including the blowpipe pontil gathering iron pucellas shears clapper woods pallet blocking wood pincers crimper glaze A discrete layer of glass on a predominantly crystalline body ie a vitreous coating applied to a core or base such as stone or clay either to make it impermeable andor for decorative effect glazing bar ferramenta An iron window bar used to support painted window glass panels glory hole A hole in the side of a glass furnace used when reheating glass which has already been molten and is in the process of being fashioned or decorated or ware which having been mould blown is re polished to remove imperfections remaining from the mould glyptic Susceptible to carving especially gems but also applicable to certain types of glass as battledore lipper and Glossary evidenced by incised relief cutting such as body sclmitt and cameo cutting green glass See bottle glass grisaille 1 Clear glass ornamented in muted colours usually including varying shades of grey with delicate often foliar patterns and leaded into decorative designs 2 A brownish paint made with iron oxide that was fused on to the surface of glass to define details in painted glass windows grozing Biting away the edge of a piece of glass usually window glass with pliers or a hooked grozing iron in order to shape it in a precise manner haematinum haematinon An opaque blood red glass in which under a magnifying glass the cuprous oxide crystals become visible against a colourless background It was made in the early Egyptian period and in the Roman period and was used in enamels and mosaics heel ball A black wax composition used in the process of painted glass restoration to make rubbings of glass panels on thin paper lainterglasmalerei backpainting mirror painting The German term for painting on the back of glass to be viewed from the front bocbsclmitt Literally high engraving The German term for all degrees of relief decoration produced on glass objects by ta21aeeZ erzgraraing It is opposite of tie ckaitt or imfaglio The process involved the making of the design in relief by cutting away the ground in the manner of a cameo relief bumper A large and wide nearly cylindrical beaker frequently of tinted tzzaldglass with straight sides and a slightly projecting base and sometimes a cover They were made of many styles and sizes some up to 600mm high and were used for drinking beer or wine hyalith A dense opaque glass coloured sealing wax red or jet black developed following the emerg ence of rubywred and other strong colours for glass at glasshouses owned by Count von Buquoy in southern Bohemia from about 1803 hyaloplastic Greek ayalos glass Relating to the decoration on glassware made by manipulation eg by blowing threading trailirzg pincering rather than by moulding pressing cutting a erzgratzmg etc iceglass A type of decorative glassware which has a rough irregular outer surface resembling cracked ice It is produced by plunging the vessel momentarily into cold water during manufacture intaglio The style of decoration created by engraving or cutting below the surface of the glass so that the apparent elevations of the design are hollowed out An impression taken from the design would yield an image in relief The background is not cut 5It N aou LrL055z239y away but is left in the plane of the highest areas of the design iridescence The rainbow like play of different colours changing according to the angle of view or with the angle of incidence of the source of illumination The iridescence results from exposure of the glass to adverse conditions and is caused by the diffraction of light from several layers that have air between them isotherrnai glazing On painted glass windows the system of protective external glazing in which the interspace is ventilated to the interior of the building in order to equalize as far as possible the temperature on both sides of the medieval glass kelp A type of seaweed the calcined ashes of which were formerly used as a source of soda in making glass especially in Normandy France and Scandi navia 39 kick A deep concavity in the base of a vessel where it has been pushed in by a tool either to make sure the vessel stands vertically or to reduce the volume of liquid inside kilnoven See reoerlaemtory furnace knop A component usually spherical or oblate of the stern of a drinking glass made in many styles hollow or solid and used either singly or in groups of the same or different types and placed contiguously or with intermediate spacing lachrymae batavicae See Raperr s drops lampworking See at tl3e ame lczrmes de oerre See Rztpert s drops lead glass glass of lead A type of glass containing a large percentage of lead oxide For practical purposes it can be considered to be a late seventeenth century English development Lead glass is dense soft and exceeds potash and soda glass in its brilliance and suitability for facet cutting When struck it emits a characteristic ring leadingup The act of assembling pieces of glass for window panels with lead strips lehr leer The oven used for annealing glassware Early lehrs were connected to the furnace by flues but the difficulty in controlling heat and smoke made it impracticable Later the lehr was a long brick lined separately heated steel tunnel through which the glass objects being annealed were pushed slowl laced in iron ans on a conve or the ware Y P P Y remained in the lehr for several hours while being gradually reheated and then uniformly cooled modern lehrs work on a conveyor belt system lime Calcined limestone which added to the glass barely in small quantities gave stability It original ly occurred as impurity in the raw materials before the seventeenthcentury when its beneficial effects became known 92 lustre painting Painting on the surface of glass with metallic oxide pigments comparable to lustre painting on pottery and producing the same metallic effect marver French marbre marble Flat surface originally of stone or marble but later of iron on which the gcztlaer of molten glass on the end of a blotwpzpe or pontil is rolled into a globular or cylindrical symmetrical mass The process is known as tnarvering metallic oxide The oxide of a metal employed as a pigment to colour glass and in making enamel colours to decorate the surface of glass The resultant colour from any metallic oxide depends on the nature of the glass itself the purity of its ingredients and the furnace conditions ie degree of heat or existence of a reducing or oxidizing atmosphere mille ori Literally a thousand owers A style of decorating glass with slices of coloured canes embedded in clear molten glass usually in flowerlike designs mirror painting See laimrerglasmalerei molten glass Glass in a rnelted state after fusing the ingredients at a high temperature until the lmtcla has become liquid then allowing it to cool until it reaches the stage when it is plastic and ductile mosaic As applied to portable glass objects rather than architectural mosaic embedded in cement in floors walls and ceilings a glass object formed or decorated with many small adjacent pieces of vari coloured glass mould A form used in shaping glassware by mouldblown or mouldpressed techniques Early rnoulds were of one or two piece construction and made of fireclay carved wood or stone and later of metal mouldblown Glassware made by the process of blowing the molten glass pcmzison into a mould The interior wall of mouldblown glass is in the shape of the outer form so that the blown object could be reheated and further blown to enlarge its size mouldpressed Glassware made by the process of pressing as distinguished from moald blotem glass muff glass See cylinder glass muffle A reclay box in which glass or porcelain objects were enclosed when placed in the muffle kiln to protect them from the ames and smoke while being subjected to low temperature ring especially in the process of applying enamel colours and fired giltling at temperatures of 500700 C natron Sodium sesquicarbonate obtained from the natron lakes northwest of Cairo Egypt It was used as the soda constituent in making Egyptian glass network former The material usually silica forming the parent or basic glass network modi er A material used to modify the basic silica glass and thereby lower its melting and working temperatures Norman slab A type of window glass made by blowing a gather of glass into a square mould The square is then cut so that each side becomes a small at piece of glass Little used at present obsidian A volcanic material which is the earliest form of natural glass used by humans It is usually black or very dark in colour but its splinters are 39 transparent or translucent and have a bright lustre offhand blown See freeblown glass opal glass A translucent white glass partly opaci ed with an oxide such as that of tin Seen by transmitted light it shows brownish or reddish tones sunset glow opaque enamel An enamel which is not transparent It was usually produced by adding tin oxide as in the white glaze on faience maiolica and delfware ceramics When used to decorate the surface of glassware it was applied thickly and hence palpable It was the principal medium for decorat ing glass by enamelling until the development of transparent enamel circa 1810 opus sectile A mosaic panel made of pieces of glass which were not fused together but were embedded in mortar See also revetment oxidation The combination of oxygen with a substance or the removal of hydrogen from it The A term is also usedmore generally to include any reaction in which an atom loses electrons eg the change of a ferrous ion Fe to a ferric ion Fe painted enamels Enamel colours painted on a plain foundation of sheet metal and red paraison A gather on a blo39wpz39pe after it has been blown into a bubble patede verre Literally glass paste A material produced by grinding glass to a paste adding a fluxing medium so that it would melt readily and then colouring it Objects were made of it in a mould and the material was fused by ring pattern moulded glass Glassware that has been blown in a mould whose interior has a raised pattern so that the object shows the pattern with a concavity on the inside underlying the convexity on the outside piece mould A mould made of two or more parts in which glassware is made in partsize or full size A partsize vessel is later expanded by blowing plastic Susceptible to being readily modelled or shaped as glass in a molten state polishing The process of giving glass pieces a smooth brilliant surface after an object has been cut or engraved Glossary pontil The iron rod to which a partly made molten object is transferred from the blow pz39pe on which the metal has been gathered marvered and tentatively blown When the pontil was removed it left a rough pontil mark on the glass This mark was polished out on better glassware pot A crucible of re clay in which the batch of glass ingredients is fused potash Potassium carbonate It is an alternative to soda as a source of alkali in the manufacture of glass Potash glass is slightly heavier than soda glass it passes from the molten to the rigid state more quickly and is therefore more difficult to manipulate into elaborate forms However it is harder and more brilliant and lends itself to decorative techniques of facet cutting and wheel engraving pressed glass Glassware made by the process of shaping an object by placing a blob of molten glass into a metal mould and then pressing it with a metal plunger or follower to form the inside shape The resultant piece termed mouldpressed has an interior form independent of the exterior in contrast to moalclbloom glass whose interior corresponds to the outer form prunt A blob of glass applied to a glass object as decoration but also to afford a firm grip in the absence of a handle purple ofcassius A crirnson purple colour that was sometimes used to colour glass The pigment was prepared by precipitating a gold solution by means of chloride of tin and then adding the resultant colloidal gold to the batch the treated glass became rubyred when reheated to strike the colour quarry Square or diamond shaped pane of glass used particularly in grisctille windows reamy glass cord Irregular streaky glass made from a mixture of glass of different hardnesses and therefore differing refractive indices its presence indicates that the glass is inhomogeneous reducing atmosphere A nonoxidizing condition in the furnace rich in carbon monoxide produced by a smoky re It affects glass in the crucible eg a red colour is produced by the use of copper cuprous oxide in the batch in conjunction with a reducing atmosphere in contrast to an oxidizing smokeless atmosphere which produces a blue green colour with copper re ning French af mzge Holding the molten glass at an elevated temperature well above its liquidus temperature so that the larger air bubbles can escape reverberatory furnace kiln oven An early type of glassmaking furnace somewhat paraboloid in shape made so that the heat from the burning fuel was reflected downwards from the furnace crown 5 232 Glossary on to the pots for maximum efficiency The pots were arranged around the inside and above them were openings bocche through which the work men inserted the rods to take out the molten glass some had a small hole glory bole for reheating a partially made glass object giving it a re polis1a revetment The general term used to describe glass stone or te racotta elements applied to a wall as pure decoration Elaborate revetments were termed opus secrile in Latin or sieoutiosis in Greek rock crystal Natural quartz chemically purequot silica It is usually colourless and translucent or nearly so From earliest times glassmakers sought to imitate it rod See cane rod formed The the technique of winding molten glass on the tip of a narrow metal tool or wire Used for making small beads larger objects required a core material so that the glass did not adhere to the rod Rupertfs drops tears glass lames de oerre lacrymae batavicae Tadpoleshaped hollow glass objects about 50 mm long having a bulbous end tapering to a thin curved tail They were made by dropping a small blob of fully molten glass into cold water and leaving it until cooled They are not affected by a blow to the bulbous end but if the tail is brokenor the surface scratched the piece due to different internal stresses explodes loudly into a ne powder sand The most common form of silica used in making glass It is an impure silica taken from the seashore or preferably from inland beds whose sand is more readily ground and is freer from impurities It should have a low iron content and must first be well washed heated to remove carbonaceous matter and screened to obtain uniform small grains seam mark A slight narrow ridge on a glass object which indicates that it has been made by moulding The seams appear where the joins in the parts of the mould have permitted molten glass to seep during the process of formation On wellmade pieces the seam marks are usually smoothed away by grinding or repolishing seed Undissolved tiny bubbles of gases or air that rise to the surface while melting the glass ingredients They show as tiny specks in the nished glass objects shearings cuttings clippings Cuttings of waste glass formed by trimming glassware during rnanu facture siege The floor of the glass furnace on which the pots sit silica A mineral which is one of the essential ingredients of glass The most common form of silica used in glassmaking was and still is sand silver A metal used in colouring or decorating glass or in backing mirrors It has been used by various techniques 1 silver leaf laid between two layers of glass 2 silver nitrate used to back mirrors and in making silvered glass 3 silver sulphide used to produce deep yellow stain or a straw yellow colour in lustre painting 4 silver foil 5 silver used to make silver electroplated glass soda Sodium carbonate It or alternatively poms399 is used as the alkali ingredient of glass It serves as a ux to reduce the fusion point of the silica in making glass Soda glass is relatively lightweight and on heating remains plastic and workable over a wider range of temperature than other varieties Soda glass therefore lends itself to elaborate manipulative techniques stannic oxide See tin oxide stipplirig The process of decorating glass by striking a diamond or hardened steel point against it so that the desired image is produced by many tiny shallow dots stipples and sometimes short lines indented in the surface of the glass The graded dots provide the highlights the intensity varies with their closeness and the shadows and back ground result from leaving the polished glass untouched stones Specks of foreign matter sometimes found in glass strain cracking Deterioration in a glass object having the appearance of tiny internal cracks in the wall of the object caused by stresses and strains sometimes due to faulty annealing or to mechanic al damage but also as a result of loss of alkali from the surface by weathering striking The process of reheating glass after it has cooled in order to develop a colour or an opacifying agent tears Air bubbles in the shape of tears encased in the stern of some drinking glasses or other glassware or occasionally in the nial of a solid Ieizop i tears glass See Rupert drops tesserae Small pieces usually roughly square of glass or other suitable material used in the formation of architectural mosaics threading 1 The process of attaching glass threads as independent decoration to be distinguished from trailing where the threads are applied to the surface of the object 2 The process of drawing glass threads through molten glass as a method 03 decoration tie clmitt Literally deep carving the opposite of inoclysclanitt Wheelengraved decoration on glass where the design is cut below the surface of tht glass in the reverse of relief tin oxide stannic oxide A chemical used to opacif Wmquot glass in making opaque white glass and also in making tin oxide glaze for pottery trailing The process of applying threads of glass as a decoration on the body handle or foot of a vessel It is done by laying or winding softened threads on to a glass object twists Decoration in the stems of English drinking glasses produced by twisting a rod of glass in which air bubbles or threads or tapes of opaque white or coloured glass were embedded undercutting The process of decorating glass in high relief by cutting away part of the glass between the body of a piece and its decoration leaving an intervening open space see wise diatreta oaszz diatreta cage cups Glass vessels in which the body is surrounded by a network or other openwork pattern of glass that is attached by small glass struts verre de fougere Literally fern glass A primitive type of greenish glass produced in France after the Roman era The ateczli ingredient was paras9 derived from burnt bracken fern tretro filigmnato See ligmmz vitri cation The process of changing the raw materials of which glass is made into a glassy Glossary vitreous substance by heat and fusion at temperatures around 13001550 C tvaldglas Literally forest glass A primitive type of glass greenish yellowish brownish produced in the forest glasshouses Waldglczsmtterz of medieval Germany The alkali ingredient was potash derived from wood ash waster A glass which was defective in manufacture or that became out of fashion and hence unsale able It was usually discarded and reused as earlier weathering Changes on the surface of glass caused by exposure to adverse conditions which appear as dulling frosting iridescence or decomposition wheelengraving A process of decorating the surface of glass with pictorial or formal designs or inscriptions by the grinding action of a wheel using discs of various materials and sizes with an abrasive in a grease applied to a wheel 39as the engraver holds the object against the underside of the rotating wheel zwiscbengoldglas Literally gold between glass A type of decoration in which a design in gold leaf was incorporated between two vessels which tted precisely together as STANDARD DEFINITIONS OF TERMS RELATING TO GLASS AND GLASS PRODUCTS The items in this list are a selection from ASTM Designation C16266 These definitions were prepared by the American Ceramic Society and the American Society for Testing and Materials 9 f quotquotquotquot39 ana Acid Polishing The polishing of a glass surfact by acid treatment Alabaster Glass A milky white glass which diffuses light without fiery color Alkali The oxide of sodium or potassium less frequently of lithium Anneal To prevent or remove objectionable stresses in glassware by controlled cooling from a suitable temperature Annealing Point AP The temperature corresponding to a rate of elongation of 00136 cmmin when measured by the Method of Test for Annealing Point and Stress Point of Glass ASTM Designation C336 This test prescribes a rate of cooling of approximately 4 Cmin with a fiber of approximately 0065 cm in diameter and a suspended load of 1000 g The annealing point numerically approximates log130 poises where internal stress is substantially relieved in a few minutes Annealing Range The range of glass temperature in which stresses in glass articles can be relieved at a commercially desirable rate For purposes of comparing glasses the annealing range is assumed to correspond with the tem peratures between the annealing point A P and the strain point St P Antimony An industrial term for an oxide of antimony Arsenic An industrial term for an oxide of arsenic Aventurine Glass containing colored opaque spangles of nonglassy material Base The bottom of a bottle Batch The raw materials properly proportioned and mixed for delivery to the furnace Bead 1 An enlarged rounded edge of a tumbler or other glass article or any Bent Glass Flat glass that has been shaped while hot into cylindrical or other raised section extending around the article 2 A small piece of glass tubing used around a lead wire curved shapes Blank l A parison or preliminary shape from which a finished article is further formed or mold for producing same 2 Any article of glass on which subsequent forming or finishing is required Blanks Pressines Optical glass formed by pressing into the rough shape and size required in the finished article Blank Mold The metal mold which first shapes the glass in the manufacture of hollow ware Blister An imperfection a relatively large bubble or gaseous inclusion Blocking 1 The process of shaping a gather of glass in a cavity of wood or metal 2 The process of stirring and fining glass by imersion of a wooden block or other source of bubbles Eg 3 The process of reprocessing to remove surfact imperfections 4 The mounting of optical glass blanks in a shell for grinding and polishing operations 78 5 The process wherein a furnace is idled at reduced temperatures 6 The process of setting refractory blocks in a furnace Block Mold A onepiece mold Bloom A surface film resulting from attack by the atmosphere or from the deposition of smoke or other vapors See also Smoked Blow andblow Process The process of forming hollow were in which both the preliminary and final shapes are formed by air pressure Blower One who forms glass by blowing See also Gaffer Blogpipe w The pipe used by a glassmaker for gathering and blowing by mouth Blowing Iron See Blowpipe Blown Glass Glassware shaped by air pressure as by mouth blowig or by compressed air 39 Blow Mold The metal mold in which a blown glass article is finally shaped Body The attribute of molten glass associated with viscosity and homogeneity which is conducive to workability Boil 1 An imperfection a gaseous inclusion larger in size than seed small bubbles 2 The comotion caused by gases escaping from the melting batch Borate Glass A glass in which the essential glass former is boron oxide instead of silica Borosilicate Glass Any silicate glass having at least 5 per cent of boron oxide B253 Burner Block Refractory block with one or more orifices through which fuel is admitted to a furnace Burnvoff The process of severing an unwanted portion of a glass article by fusing the glass Burnt Lime calcined limestone CaOMgO dolomitic or Cao calcitic or a mixture of these Cane Solid glass rods Carryin Manual lehr loading Cased Glass Glassware whose surface layer has different compositiohfrom that of the main glass body Casehardened A term sometimes used for tempered glass See Tempered Glass quotquot quotquot Casting A process of shaping1ass by pouring hot glass into molds or onto tables or molds 39 ea Charge The glassforming mixture for melting Check An imperfection a surface crack in a glass article Chemical Durability The lasting quality both physical and chemical of a glass surface It is frequently evaluated after prolonged weathering or storing in terms of chemical and physical changes in the glass surface or in terms of changes in the contents of a vessel Chill Mark A wrinkled surface condition on glassware resulting from uneven cooling in the forming process Chip An imperfection due to breakage of a small fragment out of an otherwise regular surface Continuous Tank A glass furnance in which the level of glass remains constant because the feeding of batch continuously replaces the glass withdrawn Coolingedown Period e 1 The time elapsing after a covered pot is opened before the glass is cool enough to work 2 Period between fining stage and the remoyal of the glass from the furnace Cooling Rate See Setting Rate Cord An attenuated glassy inclusion processing optical and other properties differing from those of the surrounding glass Crackled Glassware the surface of which has been intentionally cracked by water immersion and partially healed by reheating before final shaping Crackoff The process of severing a glass article by breaking as by scratching and then heating Crizzle An imperfection in the form of a multitude of fine surface fractures Crown The part of a furnace forming the top or roof Crown Flint Glass An optical crown glass bordering on optical flint glass because of the addition of a substantial content of lead oxide and with somewhat higher dispersion than optical crown glass Crown Optical Glass See Optical Crown Glass t Crystal Glass A colorless glass highly transparent frequently used for art or tableware V Cullet 1 Waste or broken glass usually suitable as anaddition to raw batch 2 Foreign cullet w cullet from an outside source 3 Domestic cullet factory cullet ecullet from within the plant h The portion of a glass article which will later be cut off and LJ discarded or remelted Cut Glass Glassware decorated by grinding figures or patterns on its surface by abrasive means followed by polishing Cutter 1 A workman engaged in grinding designs on glass 2 One who cuts flat glass 3 The tool used in cutting glass Cutting 1 Scoring flat glass with a diamond or a steel wheel and breaking it along the scratch 2 Producing cut glass Cylinder Process A process for manufacture of window glass wherein molten glass is blown and drawn into the form of a cylinder which is subsequently split longitudinally reheated in a flattening kiln and flattened Day Tank A periodic melting unit usually designed to be emptied by each day of handgathering Decolorizing The process of producing a colorless appearance in glass Deformation Point The temperature observed during the measurement of expansivity by the interferometer method at which viscous flow exactly counteracts thermal expansion The deformation point generally corresponds to a viscosity in the range from l rlto 1012 poises Dense In optical glass the subclass of a higher index of refraction Devitrification Crystallization in glass Dolomite A mineral having the empirical composition 1 mole of calcium carbonate and 1 mole of magnesium carbonate CaCO3MgCO3 See also Limestone and Burnt Lime Dummy A mechanical device operated by the b1ower39s feet for wetting raising opening and closing the paste mold in mouth blowing glassware Engraving The process of carving figures letters etc upon glass by abrasive means Etch To attack the surface of glass with hydrofluoric acid or other agent generally for marking or decoration Etched l Treated by etching 2 Weathered so that surface is roughened Fade Attack of the surface of glass causing an oily or whitish surface Fiber An individual filament made by attenuating molten glass A continuous filament made by such a process is a glass fiber of great or indefinite length A staple fiber is a glass fiber of relatively short length generally less than 17 in 39 Fine Annealigg Annealing to an extremely low stress and uniform index of refraction 394 no gp wv 1 5 Fining The process by which the molten glass approaches freedom from undissolved gases Finish 1 The part of a bottle for holding the cap or closure 2 Stage in melting process after glass appears free of seeds Finisher 1 Person having charge of a furnace during the melting and fining of the glass 2 The workman who does the final work such as polishing or putting the handle or foot on a piece of were FirePolish To make glass smooth rounded or glossy by heating in a fire Flanged Bottom An imperfection an offset bottom of a bottle Flashing Applying a thin layer of opaque or colored glass to the surface of clear glass or vice versa See also Striking Flat Glass A general term covering sheet glass plate glass and various forms of rolled glass Flint Glass 1 A leadcontaining glass 2 Term used by container industry for colorless glass Flux A substance that promotes fusion Foam A layer of bubbles on the surface of molten glass Forehearth A section of a furnace in one of several forms from which glass is taken for forming Forming The shaping of hot glass Freeblown See offhand Glass Frosted Surfacetreated to scatter light or to simulate frost Gaffer Head workman foreman or blower of a glass hand shop Gather To get glass from a pot or tank on the pipe or punty Glass Glass is an inorganic product of fusion which has cooled to a rigid condition without crystallizing a Glass is typically hard and brittle and has a conchoidal fracture It may be colorless or colored and transparent to opaque Masses or bodies of glass may be made colored translucent or opaque by the presence of dissolved amorphous or crystalline material b when a specific kind of glass is indicated such descriptive terms as flint glass barium glass and window glass should be used following the basic definition but the qualifying term is to be used as understood by trade custom c Objects made of glass are loosely and popularly referred to as glass such as glass for a tumbler a barometer a window a magnifier or a mirror Glass Blowing The shaping of hot glass by air pressure 39 Glass Container General term applied to glass bottles and jars Glory Hole An opening exposing the hot interior of a furnace used to reheat the ware in hand working Gob l A portion of hot glass delivered by a feeder 2 A portion of hot glass gathered on a punty or pipe See also Parison Hard Glass 1 A glass of exceptionally high viscosity at elevated temperatures 2 A glass of high softening point 3 Comonly refers to a glass difficult to melt 4 A glass hard to scratch Heatabsorbing Glass Glass having the property of absorbing a substantial percentage of radiant energy in the near infrared of the spectrum HeatresistingG1ass Glass able to withstand high thermal shock generally because of low expansion coefficient Heattreated Term sometimes used for tempered glass Heel Tap An imperfection in which the base or bottom of a bottle is very thick in one area and very thin in another Hightransmission Glass Glass which transmits an exceptionally high percentage of the visible light Hot End Those manufacturing operations concerned with hot glass that is melting forming annealing Hot Mold The process of forming glassware in hot uncoated molds Hot Spot The zone of highest temperature within a glassmelting furnace Knot An imperfection an inhomogeneity in the form of a vitreous lump Ladle A longhandled cupshaped tool for ladling glass out or from one spot to another Also used for filling open pots Laminated Glass See Safety Glass Lampworking Forming glass articles from tubing and cane by heating in a gas flame Lap 1 An imperfection a fold in the surface of a glass article caused by incorrect flow during forming 2 A tool used for polishing glass Lead Crown Glass See Crown Flint Glass Lead Glass Glass containing a substantial proportion of lead oxidePb0 Leaded Glass Pieces of glass fixed together with a strip lead of quotHquot or quotUquot section to form a window 3 i quot39 Lehr Leer A long tunnelshaped oven for annealing glass by continuous passage Lehr Loader A device for properly placing and spacing glassarticles on a continuous lehr belt Lime Calcium oxide cao or a mixture of calcium oxide CaO and magnesium oxide Mgo Lime Crown Glass An optical crown glass containing a substantial quantity of calcium oxide Lime Glass A glass containing a substantial proportion of lime usually associated with soda and silica Limestone Either calcitic limestone CaCO3 or dolomitic limestone CaC03MgC03 Liquidus Temperature The maximum temperature at which equilibrium exists between the molten glass and its primary crystalline phase Long A comparative term signifying a slowsetting glass Marver 1 A felt plate on which a hand gather of glass is rolled shaped and cooled 2 Also the process of doing same Melt A specific quantity of glass made at one time Melter 1 The chamber of a tank furnace where the glass batch is melted 2 Person in charge of the furnace during the early stages of filling and melting of the batch Melting The thermal process by which the charge is completely converted into molten glass free from undissolved batch Melting Temperature The range of furnace temperatures within which melting takes place at a commercially desirable rate and at which the resulting glass generally has a viscosity of 1015 to 1025 poises For purposes of comparing glasses it is assumed that the glass at melting temperature has a viscosity of 10 poises Metal Molten glass in a melting unit Metal Line The surface line of the metal or glass in a tank furnace or pot Metal Tender Person who regulates the temperature of the furnace in order that the glass may have the proper viscosity for casting 39 Milkiness A condition of pronounced cloudiness in glass Mix The mixed batch Moil 1 The glass remaining on a punty or blowpipe after a gob has been cut w h off or after a piece of were has been blown and severed 2 The glass originally in contact with the blowing mechanism or head which becomes cullet after the desired article is severed from it Mold A form usually metal in which glass is shaped Molded Glass Glass which is formed in a mold as distinct from cast rolled drawn or offhand ware Mold Lubricant A substance applied on or into molds to reduce friction or prevent adhesion Mold Mark Mark or seam on glassware resulting from a mold joint Neck 1 The part of a bottle between finish and shoulder 2 The structure connecting the melting and working chambers of a tank furnace 3 The structure connecting the uptake and port in a tank furnace Obsidian A highly siliceous natural glass offhand Glass Glass produced by the offhand process offhand Process The process of forming glassware by an expert working withont the aid of molds Offset An imperfection resulting from mold parts not properly matched that is a finish or base offset from body or neck Qpal Glass Glass with fiery translucence Loosely any translucent glass Qpen Pot A pot open to the flames and gases of combustion Optic Having variations in wall thickness product has refractive effects Qptical Crown Glass An optical glass with a low dispersion and low index of refraction usually forming the converging element of an optical system Any optical glass possessing a Nuwvalue of at least 550 or any optical system Any optical glass with a Nuvalue between 500 and 550 having a refractive index greater than 160 39 Optical Flint Glass n An optical glass with a high dispersion and high index of refraction usually forming the diverging elements of an optical system Any optical glass possessing a Nu va1ue less than 500 or any optical glass with a Nuvalue between 500 and 550 having a refractive index less than 160 Optical Glass Glass of high quality having closely specified optical properties used in the manufacture of optical systems Out ofround The imperfection of nonuroundness in glass articles oven Glass l Glass suitable for manufacture of articles to be used in baking and roasting foods 2 Glassware made from oven glass Owens Process A bottlewmaking process in which the blank or parison mold is filled by suction A 4 5539 Oxidising Agent A compound which decompses during the melting or fining stages supplying oxygen to other batch chemicals 9 Paddling The rough shaping of a piece of glass in a furnace by means of paddles or tools preparatory to the pressing operation for making optical glass blanks Parison A preliminary shape or blank from which a glass article is to be formed Parting Line Line or seam on glassware resulting from joint of two mold parts Paste Mold A mold lined with adherent carbon used wet for blown ware Pearl Ash Commercial potassium carbonate Phosphate Glass A glass in which the essential glass former is phosphorus pentoxide instead of silica Pig A rest for blowpipe or punty during the gathering operation Plain Relatively free from bubbles and seed during the melting process Plate Glass Flat glass formed by a rolling process ground and plished on both sides with surfaces essentially pland and parallel Plunger The reciprocating metal part which forces glass into the contours of a mold or which in a blank mold forms the initial cavity for subsequent blowing See also Needle Pontil See Punty Port Any opening in a furnace through which fuel or flame enters or exhaust gases escape 39 Pot A onewpiece refractory container for molten glass Open pot a pot wherein the glass surface is not protected from the furnace atmosphere Closed pot a pot having a crown protecting the glass from the furnace atmosphere Pot Arch A furnace for firing or preheating a pot Pot Furnace A furnace for melting glass in pots Pot Glass 1 Glass melted in a pot as distinct from a tank 2 Glass suitable for pot melting Potash Potassium oxide K20 Loosely a carbonate of potassium C Press andblow Process A process of glass manufacture in which the finish and parison are pressed and the parison is subsequently blown to form the final shape Pressed Glass Glassware formed by pressure between a mold and a plunger 5 r Mu it gur Pressing The operation of forming pressed glass Pull The quantity of glass delivered by a furnace in a given time usually 24 hours Punty 1 A gathering iron of solid crosssection 2 A device to which were is attached for holding during fire polishing or finishing Qoartz Glass A term applied to silica glass made by fusing vein quartz Raw Batch A glass charge without cullet Raw Cullet A glass charge made totally of cullet Reboil r Reappearance of bubbles in molten glass after it previously appeared plain Reducing Agent A chemical which at high temperatures lowers the state of oxidation of other batch chemicals Rock Crystal 1 Transparent quartz 2 Highly polished blown glassware handout or engraved Rocker An imperfection a bottle with bottom deformed so it does not stand solidly rocks Rod Proof A test specimen taken from the melt on an iron rod Safety Glass Glass so constructed treated or combined with other materials as to reduce in comparison with ordinary sheet glass or plate glass the likelihood of injury to persons by objects from exterior sources or by these safety glasses when they may be cracked or broken Types of safety glass include 1 Laminated Safety Glass Two or more pieces of glass held together by an intervening layer or layers of plastic materials It will crack and break under sufficient impact but the pieces of glass tend to adhere to the plastic and not to fly If a hole is produced the edges are likely to be less jagged than would be the case with ordinary glass 2 Tempered Safety Glass A single piece of specially heat treated glass with a stress pattern such that the piece when fractured reduces to numerous granular fragments with no large jagged edges 3 Wire Safety Glass A single piece of glass with a layer of meshed wire completely imbedded in the glass but not necessarily inthe center of the sheet When the glass is broken the wire mesh holds the pieces together to a considerable extent Sagging Process of forming glass by reheating until it conforms to the shape of the mold or form on which it rests Sand Holes Small fractures in the surface of glass produced by the rough grinding operation which have not been removed by subsequent fine grinding v 39 I V u gun 5392 Scum A floating layer of unmelted material on the molten glass surface Seam Mark on glass surface resulting from joint of matching mold parts Seed An extremely small gaseous inclusion in glass Setting Rate A comparative term referring to the time required for the glass surface to cool between the limits of the working range A short time implies a fast setting rate and a long time implies a slow setting rate Sharp Fire Combustion with excess air and short flame Also quotoxidizing flamequot Sheet Glass Flat glass made by continuous drawing Shop 1 A unit group of workmen producing glassware 2 Also its location at the furnace Short A comparative term signifying a fastesetting glass Silica Glass Vitreous silicon dioxide Si02 quartz glass pure silicon dioxide SiO2 glass Silk Screen Process A decorating process in which a design is printed on glass through a silk mesh woven wire or similar screen Slab Glass Optical glass obtained by cutting or forming the chunk glass into plates or slabs Slugeed Bottom An imperfection very heavy glass on one sie and very light on the opposite side of the bottom of a bottle or container Smoked 1 A term applied to the discoloring of glass in a reducing flame 2 Glass covered with smoky film from openefired lehrs Snap A device for gripping a piece of formed glass for fire polishing and finishing Also quotsnap ironquot Soda Sodium oxide Nag Loosely a carbonate of sodium Loosely a carbonate of sodium Soft Fire A flame with a deficiency of air Also quotReduction Flame Soft Glass Opposite of quotHard Glassquot Softening Point SP r The temperature at which a uniform fiber 055 to 0w75 mm in diameter and 235 cm in length elongates under its own weight at a rate of 1mm per min when the upper 10 cm of its length is heated in the manner prescribed in the Method of Test for Softening Point of Glass ASTM Designation C 3383 at a rate of approximately 5 C per min For glass of density near 25 this temperature corresponds to a viscosity of 1076 poises Solarization Change in transmission of glass as a result of exposure to sun light or other radiation Split w an imperfection cracked or check going from surface to surface of a glass article Stability 1 Resistance to devitrification39 2 Chemical durability resistance to weathering Stain 1 An imperfection chemical corrosion on surface of glass 2 Color applied to glass by absorption at an elevated temperature Stones An imperfection crystalline contaminations in glass Strain Elastic deformation due to stress Strain Point St P The temperature corresponding to a rate of elongation of 000043 cmmin when measured by the Method of Test for Annealing Point and Strain Point of Glass ASTM Designation C 3363 This test prescribes a linear extrapolation of the data obtained in the annealing point determination to the above designated rate Internal stress is substantially relieved at the strain point in a few hours In Stress Any condition of tension or compression existing within the glass particularly due to incomplete annealing temperature gradient or inhomogeneity Stria A cord of low intensity generally of interest only in optical glass See also Cord Striking Development of color or opacity during cooling or reheating String An imperfection a straight or curled line usually resulting from slow solution of a large grain of sand or foreign material Sweet Term applied to easily workable glass Wowt Tank A melting unit in which the container for the molten glass is constructed from refractory blocks Tank Block A refractory block used in the construction of a tank compartment of a glassmelting furnace Tank Furnace See Tank Tank Glass 1 Glass melted in a tank as distinct from a pot 39 2 Glass suitable for tank melting Tap l To drain a furnace 2 To remove excess slag from the floor of a pot furnace 394 waE Tarnish A thin film of stain on the surface of glass Temper l The degree of residual stress in annealed glass measured polarimetrically or by polariscopic comparison with a standard such as one or more strain disks sq 4 Tempered Glass Glass that has been rapidly cooled from near the softening point under rigorous control to increase its mechanical and thermal endurance Thermal Endurance The relative ability of glassware to withstand thermal shock Tit An imperfection a small protrusion on a glass article 39Toughened Glass See Tempered Glass Warmingin Reheating glass to permit further working also for striking 39Washboard An imperfection ripples waves etc on the surface of glassware Water Glass Sodium silicate glass that is soluble in water Wave An optical effect due to uneven glass idstribution or to striae Weathering Attack of a glass surface by atmospheric elements Westlake Process An automatic process using vacuum gather for producing articles in paste molds simulating the action of a hand shop Working Range The range of surface temperature in which glass is formed into were in a specific process The quotupper andquot refers to the temperature at which the glass is ready for working generally corresponding to a viscosity of 103 to 104 poises while the quotlower endquot refers to toe temperature at which it is sufficiently viscous to hold its formed shape generally corresponding to a viscosity greater than 104 poises For comparative purposes when no specific process is considered the working range of glass is assumed to correspond to a viscosity range from 104 to 107539poises NOTE It is important to remember that welding glass colored glass to protect a welder39s eyes from injurious radiations ie ultraviolet and infrared waves should be worn by glassblowers k HKLjt I II III A carefully weighed and blended mixture of THE MANUFACTURE OF GLASS WHAT IS GLASS Glass can be defined as a material obtained fronan inorganic mixture sand and other ingredients fusedat a high temperature The resulting hot liquid when cooled becomes rigid without crystallizing that is its molecules never arrange themselves into an orderly crystalline pattern now Is GLASS MADE raw materials and cullet is auto natically emptied into the batch hopper This mixture or quotbatchquot is fed con tinuously into the rear of the melting tank while the molten glass flows from the other end directly into forming machines Giant melting tanks contain hundreds of tons of glass and normally operate twentywfour hours a day and seven days a week They are made of ceramic mterisls called refractories which contain silica alumina and zirconia Holten glass is highly corrosive therefore refractory materials must resist this corrosion and must not con taminate the batch i Inside the melting tank gas or oit flames shoot out over the surface39of thequot batch from ports on either side first from one side then oethn others reversing every 20 to 30 minutes As the flames roar through the tank the dry batch heats up to around 2700 degrees Fahrenheit slowly melts forming many bubbles and starts to flow toward the other end of the tank A fire brick wall holds back any impurities floating on the surface while the pure glass flows underneath through an opening or throat Here the glass is cooler about 2000 degrees Fahrenheit and any remaining bubbles rise out of it and escape from the surface TYPES OF GLASSES Modern glasses are classified into six basic types see next few pages Raw materials and cullet scrap glass of the same type are mixed in various proportions to melt glass of each type There are many variations of each formula and many combinations of the main formula to produce special glasses On an average day as many as 450 different kinds of glass night be seen in the ordinary things around you 39 9 i 35p DE FINITION OF GLASS The American Society for Testing Materials through its Committee C14 on Glass and Glass Products has adopted the following as a standard de nition of glass as an engineering material GlassAn irioganic product of fusion which hascooled toazigid cor3di tiort without crystallizing a Glass is typically hard and brittle and has a conchoidal fracture It may be colorless or colored and transparent to opaque Masses or bodies of glass may be colored translucent or opaque by the presence of dissolved amorphous or crystalline material quotquotquot b When a speci c kind of glass is indicated such descriptive terms as flint glass barium glass and window glass should be used following the basic de nition but the qualifying term is to be used as under stood by trade custom c Objects made of glass are loosely and popularly referred to as glass such as glass for a tumbler a barometer a window a magnifier or a ITl1l39IOI39 No de nition of glass can be completely satisfactory to everyone The physicist rightly objects to having it called an undercooled liquid because cold glass is a nttremely rigid solid not liquid at all De ning it in terms of chemical composition is useless because of the great variety of existing compositions Commercial glasses are properly described by the first sentence of the ASTM definition but the converse statement does not hold Not every noncrystalline product of fusion is a commercial glass dJ1 YPIC3AL gQSS COMPOSITIONS M Q JAL 1 Luquotquot quotquot Erfg 39v F 5 0AL mwwk PKu t 0 q Mgpw fa uamp 120 013 I Q I ajoKt1gt7 hu1W O acUl s10 A1203 F3203 B503 CaO Mg a0 Nnzo K20 P150 SrO tanHintnhinlnnlunnldthuuuijI3Iampnj 51 Ijaunt Flint Container 72 5 1 005 100 08 340 05 Amber Container 39 71 5 2 2 0 35 10 0 1 9 141 0 55 Window Glass 72 0 I 5 0 E5 Hquot 9 6 Z 5 H 33 8 0 45 Talzleware 740 I Z 004 5 3 40 I M0 L4 Hcat Resisting 810 25 120 45 Fiber Glass 545 I15 85 l75 45 N 95 TV Faceplate 6L0 34 30 25 20 72 90 20 l00 quot29 TYPE OF GLASS A Soda Lime Glass B Lead Class C Borosilicate Glass D 96 Per Cent Silica Glass E Fused Silicaquot F Aluminosilicate Glass RAW MATERIALS Silica Sand Soda Ash Lime Salt Cake Feldspar Silica Sand Soda Ash 39 Litharge Pearl Ash Feldspar Niter Arsenic Trioxide Silica Sand Anhydrous39Borax Boric Acid Aluminum Oxide Silica Sand Boxax High Purity Silica Sand Silica Sand Aluminum Oxide Borax Boric Acid Limestone Magnesium Oxide quotCHARACTERISTICS For mass production Made with inexpensive materials Usedfor 902 of manufactured giass products For clarity brilliance and resistance to elec trinity For resistance to temper ature change and chemical attack For high resistance to tempterature change and chemical attack High u1tr vio1et transmission For highest transparency and electrical insulation Resistant to severe temper ature changes For extreme hardness and heat resistance L USES Continers bottles window glass mirrors b tumblers pitchers ash trays glass blocks incandescent bulbs photo flash bulbs quotCrystalquot glassware ie art glass eyeglasses optical lenses neon tubes radio TV tubes 39 capacitors radiation shielding windows 200quot alomar Disk Pyre ware laboratory glassware industrial glass piping gauge glasses incandescent lamp en closures pharmaceutical containers high tension insulators heat exchanges VycorG chemica1 ware home appliances germicidal lamps sun lamps Delay line aircraft camera high frequency electrical insulation Top of stove ware chemical ware high temperature thermometers combination tubes waterelevel gauge glasses 399 TYPE OF GLASS G Cellular Class H Optical Class I Photosensitive Glass J Photochromic Glass K Glass Ceramics FORMULA Made by heating a Nixtureof pulverird glass and a finelv divided forning gent Made of soda 1is lead borosilicte and other composigons Available in number of differenttypes which may vary ixzelectrical mechanical snd optical properties Made from silicate glasses to which silver halides are added A family of materials that have been converted into crystalline cera mics from their criginal glassy state by the use of nuclesting agents and hes t treatment CHARACTERISTICS A lightweight none combustible material unaffected by dampness and condensation High purity glasses usually of high refraction formed by techniques which yield very few quotcordsquot or other defects 39 when exposed to ultraviolet light and heat it behaves much like photographic film or paper 39 Darkens when exposed to light clears when light source is removed Darkening and clearing cycle can be repeated in definitely and the rate and degree can be controlled 39 Greater strength and hardness than the parent glass has greater abra sion resistance and im proved electrical proper ties U Insulating material for roof39construction refrigerator equipment andgpiping Lenses prisms mirrors in microscopes cameras binoculars and range finders Printed circuits tube spaces micromodule wafers dial faces lighting panels Proposed uses Windows sunglasses optical memory and se1f erasing display devices quotlight valvesquot in optical systems Pyrocera 39glass ceramics are used for nose cones cook reezeserve utensils and tableware IV SPECIAL GLASSES Most glasses are variations of the six basic types above emphasize certain properties or processing techniques TYPE OF CLASS A Colored Glasses quotA3 I K l39f B Opal Glasses C Electrically Conducting C1388 quot1quot 2 D Radiation Controlling C1883 E395 139 E Hultiform Glass 5quot3f jquoti1l lt3 F Fibrous Glass I n39 id 1 ltw39J FORMULA Made by adding small amounts of coloring materials oxides of certain metals to glass batches Opal glasses are pro duced by introducing small particles in transparent glass Made by permanently bounding a thin metallic oxide coating to the surface of the glass Sodamlime and lead glasses plus stabilizing materials Formed by powdering a glass pressing or slip casting the parti cles to shape than firing at high temperature Glass fibers can be drawn from a number of glass compositions CHARAC39I ERI39STICS Produces various colored glasses to exact standards The particles disperse the light through the glass producing an opalescent appearance This transparent coating can conduct electricity Coated glass panels can be made in various shapes and sizesfor heating Prevents transmission of radiation by absorbing gamma rays Normally translucent but also can be made transparent E Heat and acid resistance non combustib1e an excellent electrical and thermal insulators Special glasses are obtained by adjusting tie formulatior USES Signal ware light filers lamp bulbs sun glasses quotLighting lenses tablewar decorative building panel Heating panels heatshieln for protection against the infrared electrostatic shields resistors 39 Shielding windows in nuclear laboratories hospitals and aboard 39 atomic vessels Chemical apparatus mechanical and electrical parts glass to metal seals 39 39 39 Insulation textiles fabrication of boats fishing rods aircraft and missile parts 39 56 V PROPERTIES OF GLASS A Mechanical Properties Glass strength is directly related to the condition of the glass surface A rod of ordinary glass with perfect surfaces may be as strong as steel Normal handling introduces surface imperfections that limit the ultimate strength of the glass Composition has little practical effect on glass strength but glasses that resist scratching give better service The hardness of most glasses on the Mob scale is about 5 Therefore most glasses will scratch mica mild steel copper aluminum and marble Common materials that are hard enough to scratch glass include sand hard steel and emery Glass can be considered a perfectly elastic material up to the point of fracture at room temperature No matter how much force is applied as long as this force is not sufficient to cause fracturing the glass will return to its original shape when the force is removed Chemical Properties Corrosion resistance or chemical inertness is the outstanding chemical property Class will not be attacked by acids normally encountered but is only affected by hydrofluoric acid concentrated phosphoric acid and hot concentrated alkaline solutions Chemical durability is in varying degrees Borosilicates and 962 silica glass are normally used where acid attack is a problem Prior chemical or heat treatment can modify chemical durability Thermal Properties Classes are poor conductors of heat Most of the energy from high temper ature sources that is transmitted through glass is transmitted by radiaw tion rather than conduction The thermal shock resistance of glass is related to the coefficient of expansion the extent to which a material expands per degree of temperature rise Glasses with low coefficient of expansion have greater resistance to thermal shock For example highwsilica glasses and borosilicate glasses have lower coefficients of expansion than sodalime glasses and therefore can be used for making cooking ware and laboratory apparatus which must be able to withstand thermal shock Proper annealing is very important for removing internal stresses which otherwise could cause a glass to crack when it is exposed to a sudden thermal change or mechanical impact Nuclear Properties Radiation shielding glass is made from extremely dense lead glasses and from other types of glasses that are stabilized to prevent discoloration or darkening under nuclear bombardment Most glasses darken and gradually lose their transparency when subjected to xrays and gamma rave VI H Al 6 Radiation dosage indicator glass is usually of a nonwsilicate type After exposure these glasses will fluoresce under ultraviolet light in direct proportion to the amount of nuclear radiation they have received Electrical Properties The primary electrical property is that of insulation Resistance to the conduction of electricity depends on the type of glass temperature of the glass and surface conditions A film of moisture particularly in the presence of dirt or dissolved gases lowers the surface resistivity The effect can be reduced by treating the glass surface with water re pellent silicones so that moisture forms droplets rather than a film Glass is unique in that a wide range of dielectric constants is available The dielectric constant of glass is a measure of its ability to store up electricity Glasses with a low dielectric constant are required for highwfrequency and high voltage insulation Glasses with a high dielectric constant areneeded for electronic capacitors Optical Properties The optical properties which can be controlled are refraction the bend ing of light rays as they pass through a piece of glass dispersion the amount of light returned from a glass surface and color the relative 39 amounts of light of different wavelengths or color which are transmitted or absorbed by the glass The color of a glass is determined by its chemical composition and in some cases by heat treatment FORMING OPERATIONS Blowing The turret chain machine produces large size glassware and bottles First the neck of the container is formed by pressing or blowing The object is then completed by blowing into a second mold 39 The Corming ribbon machine can make up to 2000 light bulb envelops a minute Molten glass flows from a melting tank through a pair of rollers to form a moving ribbon of glass The ribbon which moves on a steel track sags through holes as air is introduced from above At the same time molds come up from below to clamp around the molten glass More puffs of air 5111 the glass into the mo1d39s shape The molds separate and pull away and the im ch amp bulba ara than knocked onto a conveyor In hand blowing a team of men work under the direeesae as a ga er who is Ye ponsible for the quality of the finished product and performs the most difficult operations A gob of molten glass is gathered on the end of an 1T0 b1 VP1P A 4 blow through the pipe to form the hot glass into a hollow ball The size shape and wall thickness is controlled by the amount of air forced into it the angle at which the pipe is held and the degree to which the glass cools During forming the glass can be cut pressed and stretched with simple tools Additional gathers can be added to form handles feet and stems The piece is reheated in 3 small furnace guring Ege forming operation to keep it pliable The glass may be ehaa y a no BO Pressing Pressing is usually the leastcostly method of forming glass From a large tank glass gobs are continuously fed into the molds of a rotating press The mold moves under a plunger which forces the glass into its air streams The slightly cooled finished piece is transferred to a moving conveyor belt Hand pressing is used for limitedrun special items The molten glass is gathered on a solid steel rod The white hot gob of glass is held over the mold and the required amount is cutoff with hand shears A plunger is forced against the glass which takes the form of the mold Drawingh Tubing g In the automatic process molten glasszflows directlyfrom the furnace 39 and passes around a ceramic or metal cone mandrel The glass is then pulled rapidly along a series of pulleys Air blowing through the center of the mandrel helps maintain the glass as a continuous tube The dimensions are controlled by speed of drawing glass temperature and amunt of air pressure 39 Tubing may also be drawn by hand A gob of glass is gathered on a blowpipe and rolled into a partially conical shpae A small bubble of air is then forced into the gather and the unsupported end is attached toanother iron Two men can then stretch the glass by walking away from each other Sheet or window glass is produced by drawing molten glass directly upward between jets of flame which fire polish both surfaces and makethem trans parent To start the drawing ofthe sheet a quotbaitquot or iron bar is intro duced into the molten glass which adheres to it As soon as the glass sheet is gripped by the rolls in the drawing machine the bait is no longer needed and is removed through the top of the machine As the glass leaves the draw pot both edges pass between watercooled knurled rolls which keep the sheet at a constant width Plate glass is made by drawing a ribbon of glass 100 or more inches wide from the furnace on rollers through the annealing lehr and directly to twin grinding heads This continuous ribbon of glassis then cut into sections and polished 39 Fiber glass is made by machines which form molten glass into marbles39 After inspection the marbles are remelted and formed into molten glass again The molten glass is then pulled through tiny holes at very high speeds 23 miles a minute and drawn into long thin fibers Glass fibers can also be made by drawing directly from the batch Float Process This is the newst method of manufacturing flat glass An endless ribbon of molten glass leaves the furnace and moves across the surface of a bath of molten tin Gravity keeps the liquid tin flat While the glass is I 1 4 3 2 9II A 9 still semimolten it is uniformly supported by and C0nf rm3 to the surface of the molten tin The temperature of the glass can be lowered as it moves across the liquid tin until it is hard enough to be conveyed through the annealing oven while still retaining the flatness developed in the tin bath 39 39 Casting Casting is a difficult method of forming glass and is usually restricted to large simple pieces Pieces of glass can be heated in a clay mold until they melt and flow into the mold shape Glass can also be melted separately and then poured into the mold 39 FINISHING GLASS Thermal Finishing Annealing is a controlled heating cooling cycle that is carried out in an oven or lehr a long tunnel with a conveyor belt The process helps re move strains in glass that are caused by uneven cooling when the piece is being formed After forming glass can be heated nearly to its softening point removed from the source of heat and quickly chilled This process called tempering can increase mechanical and thermal endurance two to four times Sealing is a process where two pieces of glass can be fused together with the aid of a gas flame or electric heat Surplus glass can be trimmed by a flame cut off In netslizing glass metals can be sprayed on a cold or hot glass surface Noble metals for example gold and silver can be fired on at high temperatures Glass to metal sealing is used when there is a problem of satisfactorily matching coefficients of expansion of a glass and a metal A series of glasses with slightly increasing or decreasing expansion coefficients are joined to one another A low expansion glass at one end of the seal is designed to match the glass body A relatively high expansion glass at the other end matches the metal body A lampworker manipulates pieces of glass rod and tubing into complex labware with the heat of a gas burner Chemical Finishing Hydroflouric acid can be used for quotfrostedquot effects quotsatinquot glass polishw ing when mixed with sulfuric acid decorative effects like cameo glass and graduate markings The glass is first covered with an acidwresisting wax Lines forming the design are then cut through the wax with a stylus when the glass is dipped in the acid the glass is etched where the war was cut 39 v ZCL Immersion in a chemical bath etches images in photosensitive glass Glass can be stained by copper or silver compounds The chemcor process chemically strengthens glass articles C Mechanical Finishing In cutting less a diamond or some other hard material is used to score the glass Mechanical force or heat is then applied near the score mark to break the glass st the desired point Edges can be ground to make them square end joints are ground for vacuum tight scientific apparatus Abrasive materials such es diamond grains and silicon csrbids are suitable for grinding glass Polishing is used when s smooth eccurstelywfinished surface is desired Finely powdered materials such so ferric oxide or cerium oxide are used for polishing GLASS AIDS FOR STUDY The Department of Education The Corning Museum of Glass orning Glass Center 51567 g qv tIIvr hilt 7 R E Ruesser An Investigation of the Organic Hoses in Gilaunite Mb thesis University of Utah Salt Lake City Utah 1949 8 J M Sugihara and D F Sorenaon J Am Chem Soc 77 963 1955 9 39I F McCullough Hydrocarbons and Other Compounds Obtained from Gilsonite PhD thesis University of Utah Salt Lake City Utah 1955 10 L R McGee Porphyrins in Gilsonite PhD thesis University of Utah Salt Lake City Utah 1956 General References quotGilsonite Cementquot Oil Can J 571 150 I959 A Bczzant The Chromatographic Separation of Gilsonitc thesis Brigham Young University Provo Utah 1949 G A Carey and l C Roberts History Occurrence Mining and Economics of Gilaonite thesis University of Utah Salt Lake City Utah I949 A L Crawford Gilsonite and Related Hydrocarbons of the Uintah Basin Utahquot The Oil and Gas Possibilities of Utah Utah Gaol Mineral Sunv Salt Lake City Utah 1949 pp 235460 C Davis Geology of the Culmer Vein of Duchesne County Utah thmia Brigham Young University Provo Utah i952 P J Grantham and A G Douglas Adv Org Geochem Proc 7th Int Meet 1975 pp 193 207 M lnagaki Y Tamai and S Nana Tonto 75 118 1973 Chem Abstr 82 33i41t 1975 9 US Pat 4073659 Feb 14 1978 M V Burris US Pat 4133932 June 18 X976 S H Pack to USM Corp US Pat 086195 Apr 25 3978 W R Knox J C Hiil L J Hughes and P W Foerst to Monsanto Co Can Pat 972 Aug 5 2975 F F Sullivan to Rotary Drilling Services lnc KENNETH R issx American Gilsonite Co GIN See Beverage spirits distilled Oils essential vol 1 GLASS Structure 809 p 852 P omposi 39 8 l gnglephiiiigiassies 813 P A n Ciasrceramics and phaseseparated glasses 818 Z I A Properties 825 Manulacuse and processing 846 commit aspects 8 Glass was formed naturally from common elements in the oarth s crust long be J fore anyone ever thought of experimenting with its composition molding its shape or putting it to the myriad of uses that it enjoys in the world today Obsidian ll n in stance is a naturally occurring combination of oxides fused by intense volcanic heat and vitri ed made into a glass by rapid air cooling its opaque black color comes from the relatively high amounts of iron oxide Its chemical durability and hardness compares favorably with many commercial glasses 1 Pumice a naturally occurring foam glass is replete with tiny pockets of the gaseous products of the decomposition of many compounds These gases were trapped by the viscous glass while it was cooling 39 The origin of the first synthetic glasses is lost in antiquity and legend Faience was made by the Egyptians who molded gurines from sand S502 the most popular glsssforming oxide They coated them with nation the residue left by the ooding Nile river which was composed principally of calcium carbonate CaCO3 soda ash Na2CO3 salt NaCl and copper oxide CuO Heating below 1000 C produced a glossy coating by the diffusion of the fluxes Ca and N320 into the sand and their subsequent solidstate reaction with the sand The copper oxide gave the article an appealing blue color Glass technology has evolved for six thousand years and some of today39s principles date back to early times This includes what is today known about the structure of glass its composition properties method of manufacture and uses see also Glassceramics Glassy metals Common usage of the term glass follows the de nition of Morey 2 Glass is an inorganic substance in a condition which is continuous with and analogous to the liquid state of that substance but which as the result of a reversible change in viscosity during cooling has attained so high a degree of viscosity as to be for all practical purpw rigid Similarly ASTM 3 definm glass as an inorganic product of fusion that has cooled to a rigid condition without crystallizing Both organic and inorganic materials may form glasses if their structure is noncrystalline ie if they lack longrange order This includes some plastim metals 47 and organic liquids 89 In principle rapid cooling could prevent crystallization of any substance if the final temperature is sufficiently low to prevent structural rearrangement Thus glasses are formed pri marily for kinetic reasons Glass is not merely a supercooled liquid This distinction is illustrated by the volume temperature diagram shown in Figure 1 When a liquid that normally does not form a glass is cooled it crystallizes at or slightly below the melting point path A If there are insufficient crystal nuclei or if the viscosity is too high to allow sufficient crystallization rates undercooling of the liquid can occur However the viscosity of the liquid rapidly increases with decreasing temperatures and atomic rearrangement slows down more than would be typical for the supercooled liquid This results in the deviation from the metastable equilibrium curve which in tlenittori lw nntlxo R me man Transformation 333 ran ltgt 939quot o Voiurne uquottquot quotquotquotquotquotquotquotquotquotquot 39 Temperature Figure I Volumenternperature relationships for glaaiim liquids supercooled liquids nd WWW Courtesy of Coming Glass Works C in Figure 1 This change in slope with temperature is characteristic of a glass Structural rearrangement is too slow to be detected experimentally and additional volume changes are virtually linear with continued cooling the same as for any other single phase solid The cooling rate determines when the deviation begins to occur Slower cooling path B for instance results in less of a deviation from the extrapolated liquid curve Figure 1 shows that the point of intersection of the two slopes de n a transformation point glasstransition temperature T for a given cooling rstile Practical limitations on cooling rate de ne the transformation range 7 D Ty 881 0 temperature range in which the cooling rate can affect the structure8enBltVe BT09 erties such as density refractive index and volume resistivity 19l The 5l3939 7t ei which is frozen in during the glass transformation persists at all lower temperatur Thus a glass has a configurations or fictive temperature which may differ fron I actual temperature The fictive temperature is the temperature at which the E 353 structure would have been the equilibrium structure 1 1 lt describes the trliittlllife of a glass as it relates to the cooling rate A fastquenched glass would have a lg 81 fictive temperature than a slowly cooled glass Glasses can be prepared by methods other than cooling from a liquid stata eluding solution evaporation reactive sputtering vapor deposition ellllolg t the bardrnent and shockwave vitrification 12i3 These techniques suggest t s ed purely kinetic explanation of the glassy state is subject to question and that We he to modify the previous de nitions It has been shown 14 that extrap0l8t 3t that thermodynamic properties of the supercooled liquid gives the paradoxical resu ml entropies heat contents and volumes become less than those of the perfect CW8 u at the same temperature Considering the transforination as a secondorder transition 15 has yielded a satisfactory explanation for the properties of some organic systems but this theory is still subject to confirmation for inorganic glasses The dependence of transformation temperature on reiaxation time has been considered and s new de nition based on structural factors proposed 16 Isotropic materials with long anucturalrelaxation times eg gt103 a would be defined as glasses The determination of either the isotropy of the material or structural relaxation times distinguishes whether or not the material is a glass This de nition requires information regarding structure and does not consider previous thermal history as a distinguishing charac teristic of a vitreous material Strirctise The basic structural unit of silicate glasses is the siliconoxygen tetrahedron in which a silicon atom is tetrahedrally coordinated to four surrounding oxygen atoms Oxygens shared between two tetrahedrons are called bridging oxygens In pure vitreous silica virtually all oxygens are bridging Those that are not shared for one reason or another can be referred to as nonbridging oxygens The relationship between these tetrahedra is controversial and has yet to be completely resolved The earlier crystallite theory has been modified by proponents of the randomnetwork theory Modern structural methods point to a compromise theory see Silica In 1921 Lebedev 17 noted a discontinuous index of refraction of SiO2 near the ci 5 transition of quartz His data and subsequent x ray investigations of vitreous silica led to the suggestion 18 that crystallites on the order of 15 nm were present It was demonstrated however that the crystal size would be less than 08 nm and it was suggested that the term crystal lmes meaning for these dimensions 1920 Zachariasen formulated the randomnetwork theory of glass in 1932 21 It proposes that atoms present in glass form a threedimensional connected structure without periodic order and with energy content comparable to that of the corre sponding crystalline material According to this theory the coordination number of an atom determines its role ins glass structure and the following four rules should be ful lled for an oxide to form glass I each oxygen atom must be linked to no more than two mtions 2 the number of oxygen atoms around any one cation must be small is three or four 3 the oxygen polyhedra must share corners not edges or faces to form a threedimensional network and 4 at least three corners must be shared For onecomponent glasses each polyhedron shares corners with at least three other polyhedra in such a way that the network is continuous in three dimensions In inul ticomponsiit glasses additional cations are distributed throughout holes in the net work Xray structural work strongly supported the random network theory 19 The way scattering pattern of glass after Fourier analysis gives radial distribution curves that indicate the distribution of neighboring atoms about a central atom No evidence of discrete particles or voids supporting an ordered structure was swerved based upon data for the first coordination shell 19 There were both theoretical and experimental limitations to this early work Later more complete data were obtained using fluo rwoence excitation to eliminate Compton scattering 22 Not only was a siliconoxygen distance of 0162 nm observed but also peaks at 0265 nm for the oxygen oxygen distance 0312 nm for the silicon silicon distance 0415 nm siliconwsecond silicon YA and 064 nm for the siliconethird oxygen peak X ray scattering investigation of silica 2324 suggested a structural ordering beyond the distances first reported 22 Data analysis resulted in a shorter siliconoxygen bond distance 11595 nrn than reported at first 22 However a similarity in bonding topology between tridymite and silica giass does not imply rnicrocrystailinity of vitreous silica in a crystallographic sense The signilarity between crystalline and vitreous structure on the basis of silicon oxygensilicon bond angles and hence the relative orientation of the silicon tetra hedrons is pointed out in Figures 2 and 3 In addition to the question of longrange ordering 12 nm there still are aspects of the randommetwork theory that are often criticized It is possible for example to form glasses when no threedimensional network is possible Glassy orthosilicates SiO4 of lead or sodium and calcium have been prepared 26 Furthermore mod ifying cations have been shown to occur at regular interatomic distances ranging over several coordination shells 27 Darkfield transmission electron microscopy has been used to infer density fluctuations of silica which suggest ordered regions of approxi mately 10 nm in size see Analytical methods However these results have been criticized 28 Glassforming systems other than silica have been examined The fraction of three and fourcoordinated boron in borate glasses can be determined by mm 29 see Analytical methods Both nmr and pray diffraction 30 results led to the sug gestion that the boroxyl ring is the structural unit of vitreous B203 2229 The in termediate size boroxyl ring represents a compromise between the crystallite and the randomnetwork theory 10 06 quotquotquot V ta 0 9 l 1 1 2 1 120 130 N0 150 160 170 180 a degree Figure 2 The distribution of siliconoxyger silicon bond angles in vitreous silica 2225 The function Visa is the fraction of bonds with angles normalized to the most probable angie 244 This dis tribution gives quite a regular structure on the short range with gradual distorting over a distance oil or 4 rings 23 nm Crystalline silica such an quartz or criatobaiite wouid have a narrower distribution around speci c bond angles VOL 11 crass an Fwure 3 Schematic representation of a an ideal crystalline structure Si0 Si bond angles a 130 and hi 9 simple giasa Si0 Si bond angle as 144 l according to Fig 2 The tetrahedra an the schamatim represent four oxygen ciuntered around a silicon as shown c Courtesy of Coming Glass Works Cmrwition Conditions favorable for glass formation may be deduced from either geometric or bond strength considerations On the basis of the rules 21 discussed above the following oxides should be glass formers B203 Si02 Ce02 P205 A3205 P303 A3203 Sb203 V205 Sb205 Nb20g and Ta205 In fact they are all so used The only uoride that ful lls the rules of glass formation is BeFg which readily forms a glass 31 Glass formers generally have cationoxygen bond strengths greater than 335 kilmol 80 kcalrnol In multiplecomponent systems oxides with lower bond strengths do not become part of the network and are called modi ers Oxides with energies of ca 335 kJrnol may or may not become part of the network and are referred to as intermediates The dissociation energies used to predict glass formation are calculated taking into account the coordination number of the cation see Table 1 In multiplecornponent glasses the terms formers modi ers and intermediates are frequently used to define the role of the individual oxides However an element such as lead may M either a modi er or intermediate depending upon its coordination and the glass system considered Glass formation of individual oxides can be predicted from the melting point and individual bond energies can be normalized by dividing by the melting point of the oxide 33 This ratio is relevant because the melting point is related to the amount of thermal energy available to rupture bonds If the bond energy is large and the melting point low glass formation is favored This explains the ease of glass formation 97 B203 and from owmelting eutectim in which neither oxide forms a glass separately eg Ca0A1203 3920 3 To convert J to cal diVid9 bi J34 use 1 Coordination haanber and Bond Strength of Oxides CAS Registry Dissociation Coordination Singiebond Oxide Number energy kJlmoiquot number strength kJmoi Former 30 r3o3ss2 1439 3 496 5102 0097286 774 4 443 G90 I3I0538 1803 4 450 M293 11344 23 1 16324326 4 4294332 30 1303as2 use 4 372 pg 345a 7 1349 4 462370 W3 I3I462 1 1 I879 4 489 376 A3205 U303282 146a 4 355292 350 34so9 ms 4 354234 20 U314234 2029 5 333 Intermediates rm mas67 7 aszs 6 303 gnu m132 aoz 2 39 pm 73173ss 606 2 03 22 M203 117442311 16824326 6 268 Th0 U3142o1 2159 8 261 Ben 11304569 2046 4 253 20 1m234 2629 3 248 jdo 13051901 498 2 Modifiers 330 112060981 I514 6 M0 312818 1599 7 208 yg 1314359 mas 8 193 3n2 passe o5 I163 6 136 320 112024214 1117 6 mo 139 372 432 mi 5 179 Th0 usi 2o 2159 I2 16 Poo 111095001 970 6 W Mgg u3os 4s 4 929 3 159 139 2a57243 602 4 51 pm 137way 6 4 150 gag 3t432 602 4 35 Eat li39 235l 1083 8 34 jag so57aa 2075 8 m 50 1374n o 1071 3 13924 C40 I6I90 493 4 83 g ma593 502 5 32 jdg mos90 498 6 53 K20 H213545 7 4s 9 3 350 mossit4 43 I0 47 Hgg 2z9os 53 2 284 6 19 C920 2o2sroo9 477 I2 1 Ref 32 Vol 11 bLAsb E 3 Other correlations of glass formation and properties have been offered For ex ample 34 I cation valence should be either three or greater 2 glass formation should increase with decreasing cation size 3 the Pauling electronegativity should be between 15 and 21 Using these criteria four types of oxides are described 1 strong glass formers such as Si B Ge As and P 2 intermediate formers that require rapid cooling such as Sb V W Mo and Te 3 oxides that form glasses in binary mixtures with nonglass formers such as Al Ga Ti Ta Nb and Bi and 4 oxides that do not form glasses Glass composition work starts with the application of structural and bonding rules of glass formation Numerous ternary systems and their glassvforming regions have been investigated 35 There are three types of ternaries A single former and two modi ers B two formers and one modi er and C three glass formers Type A is shown in Figure 4 The structural rules suggmted by Zachariasen can also de ne likely regions for glass formation Additions of several percent of other oxides for property adjustments are usually made to each system to give commercially useful glasses Sfsgle im dasses Vitreotn Camp Vitreous silica is the most important single component glass Highly crosslinked vitreous silica is vicous and has a thermal expansion coefficient within the 0 3m C range of about 55 X 10 C It is an excellent dielectric and resists attack by most chemicals except uorides or strong alkali Fused silica has a high spectral transmission and in addition is not subject to radiation damage which results in browning of other glassm It is the ideal glam for spacevehicle windows windtunnel windows ultrasonic delay lines cruciblm for growing nltrapure silicon or germanium crystals and for optical systems in spectrophotometric devices The same properties that make transparent fused silica useful also cause it to R difficult to produce and expensive Vitreous silica may be made by several processes SiO 56 E9 so cao Ao so sure 4 Gassforn1ing region in Type A system 35 The shaded area reprments the predicted Einssforming region based upon 7achariasen39s ruies 314 LnA55 Fused quartz made by electrically fusing quartz crystal gives a product containing very little moisture and having good ir transmission However mineral IrnpurIties of natural quartz including alumina iron and some chlorides reduce uv transmission Flame fusion of quartz or ame hydrolysis of SiCl4 on the other hand gives glasses containing larger amounts of water which decreases the ir transmission see below under Vapor Deposition Long heat treatments of vitreous silica below 1723 C may cause crystallization Stable crystalline forms of silica at atmospheric pressure are cristobalite 1723 I470 C tridymite l47086397 C and quartz below 867 C see Silica vitreous silica Silica synthetic Q 3quottzl Multicomponanl Siticale Systems Most glasses fall into the category of silicates containing modifiers and intermediates Addition of a modi er such as sodium oxide Nazi to the silica network alters the structure by cleaving the Si O S bonds to form Si0Na linkages see Fig 5 Separating the silica tetrahedra from each other makes the glass more fluid and therefore more amenable to conventional melting and forming methods Modi ers 1 in o sea the breaking of one Figure 5 The ddlllonflf a modifier in this case one fra olcczs e laL2wfk S 3 4 imnd in mm two Si IquotNa linkages f nurtcsv 0 0 NE I VOL I I f3 J 5 ii or uxes also cause a decrease in resistivity an increase in thermal expansion and generally lower chemical durability Glasses with a Si02NagO molecular ratio less than one have so many nonbridging oxygens that they lack a continuous threedi rnensional structure Zachariasen s rule 4 Such glasses referred to as invert glasses have been made containing Li20 NagO and K20 oxides Alkali silicates that have a silicazalkali ratio of 05 34 are the basis of the soluble silicate glass industry The cornpmition and uses of sodium silicates for adhesives cleansers desiccants abrasives cement deflocculants and surface coatings are discussed in ref 36 see Silicon com pounds The effectiveness of an alkali oxide eg Lig0 Cs2O as a flux increases with the size of the cation and therefore with its polarizability Large ions such as cesium are easily polarized and thus more likely to give up their oxygen to break the Si0 Si bonds as discussed above Lithium on the other hand is more likely to keep its oxygen and therefore its fluxing power is less This is consistent with the ease of glass for mation as the sizecharge ratio of the modifier is increased Phase separation occurs often when less polarizable oxides are present Lithium or magnesium silicates have a tendency to phaseseparate during heat treatment 37 Ionic mobility is related both to charge and to size Large alkalies are expected to be more mobile because of their greater polarizability Increased size however tends to reduce mobility Alkaline earth silicates behave similarly to alkali silicates but the fluxing power of alkaline earths is less than that of the alkalies Mobility of divalent ions is less than that of monovalent ones hence resistivities of alkalineearth glasses are usually higher Divalent oxides increase the resistivity of alkali containing glasses Alumina is frequently used in silicate glasses It often adopts a founcoordinated structure with alkalies giving a NaAlO2 tetrahedral unit which substitutes into the Si02 network The extra negative charge associated with the four bridging oxygens surrounding Ali is offset by the Na ion A maximum in viscosity occurs when the Al2O3Na2O ratio equals one Boron oxide often behaves as a flux Boron softens glass for easier melting but unlike alkalies boron oxide increases expansion only slightly This is the basis of the easily melted but lowexpansion commercial glasses known as borosilicates MelaKane Glasses Mixtures of alkali and alkaline earths give glasses of higher durability than the alkali silicates The actual compositions are usually more complex than the term soda lime suggests In addition to Na2O Ca0 and Si0g these glasses may contain MgO A1203 Ba0 or K20 and various colorants Alumina increases du rability whereas Mg0 prevents devitrification Sodalime glass accounts for nearly of all the glass produced The batch materials are inexmnsive and relatively easy to melt Sodalime glass is used for containers flat glass pressed and blown ware and lighting products where exceptional chemical durability and heat resistance are not required 1 g s 39 R ale Aampes Replacement of alkali by boric oxide in a glass network gives a lowerexpansion glass The fluxing action of the boron facilitates melting by weak ening the network This has been attributed to the presence of planar threecoordinate barons that weaken the silicate network at high temperature Phase separation of borosilimte glasses often occurs during heat treatment which may be useful for certain applications However most commercial borosilicate glasses have compositions that are miscible and homogeneous Borosilicate glass is applied as ovenware laboratory equipment piping and sealedbeam headlights 6 Aluminosilicale Glasses Structural rules suggest that if the R OA20 or the ROAl30 molar ratio is unity an aluminosilicate glass has a silica structure in which all oxygens are bridging oxygens This is true of other silicate minerals and appears to be the case with glasses Alumina is expected to be fourcoordinated when the alkali to alumina molar ratio is greater than one but if the ratio is less than one sixfold coordination of alumina has been suggested Aluminosilicate glasses are used commercially because they can be chemically strengthened and withstand high temperatures Thus applications include airplane windows frangible containers lamp envelopes and topofstove uses Lead Glasses Lead oxide is usually a modi er although at times it may act as a network former Lead glasses may be easily melted and have a long working range and a high refractive index which makes them useful for lead crystal optical glass and handformed art were Leadcontaining glasses effectively shield highenergy radiation and are therefore used commercially for radiation windows fluorescentlamp enve lopes and television bulbs Lowmelting solder glasses and frit or decorative enamels are usually based upon lowmelting lead compositions see Enamels aware Classes Borates including vitreous B203 have been studied more than any other glass forming system with the exception of siliwtes 38 Vitreous boric oxide has a threecoordinate structure consisting of sixmembered rings of alternating boron and oxygen atoms Many physical properties of alkali borate glasses show a minimum or maximum at 1530 rnol modifier boron anomaly Coordination changes of mron are detected by nrnr ir Raman and ear techniques see Analytical methods Broad quadripolar coupling typical of triangular boron coordination is readily distinguished from the sharp coupling of fourcoordinate boron 29 The fraction of tetrahedral borons present appears directly proportional to the alkali to boron ratio as long as this ratio is less than 05 38 The very low durability of borate glasses precludes their use in all except the most special applications Low molecular weight Lindemann glasses Li20BeOB2O3 were developed as x ray transmitting glasses Rareearth borate glasses have optical uses because of their high refractive indexes and low dis persion Additiona of Gd2O3 to the latter increase the index but not the dispersion 39 Phosphate Classes The structure of phosphate glass appears to be based on the phosphorous oxygen tetrahedron see Phosphoric acid and phosphates Like the borates they tend to have low durability Important commercial applications of phosphate glasses do exist however Because the absorption bands of iron oxide in phmphate glasses are sharper in the uv and it than in silicate glasses ironcontaining phosphate glasses are nearly transparent to visible light Almost clear heatabsorbing glasses with several percent iron oxide are possible Phosphatebased glasses also are more resistant to uoride than silicate glasses Some of the optical glasses produced by Schott Iloya OwensIllinois and CorningSovirel use phosphate as the primary glass former Fluorophmphate glasses designated FK5 or FK50 by Schott have very low optical dispersion with Abbemumbers of 704 and 815 respectively Other Oxide Glasses Germanium arsenic and antimony oxides all form stable glasses and their structures have been predicted The germania glass structure is quite similar to silica Infrared transmission of gerrnania glasses is higher than that of silica Teiluriurmcontaining lead glasses with a very high refractive index gt20 are also used commercially vua I r uuua o if Chalcogenide Glasses Glasses based upon sulfur selenium or telluriurn rather than oxygen are well known These glasses although often opaque to visible light transmit ir radiation of a much longer wavelength than oxide systems and many are also semiconductors qv Conductivity usually increases with increasing atomic number The mmbstudied chalcogenide glasses contain the Group V elements arsenic and antimony Halide Glasses Although examples of zinc chloride glasses are known Beliz containing glasses are more common 31 Vitreous beryllium uoride has a tetrahedral structure analogous to silica Its unique spectral properties including transmission from ltI6O run to 5500 nm low refractive index and very low dispersion have aroused considerable interest in beryllium uoride glasses Vitreous BeFg is very hygrmcopic but addition of other fluorides such as AIF3 or alkali and alkaline earth uorides increases durability Selected compositions also resist devitrification and have optical properties that are not obtainable with oxide glasses A refractive index of 13 with a dispersion of 100 is not uncommon for beryllium fluoride glasses The toxicity of beryllium is however a concern associated with melting and forming operations Metakic Hasses Under highly specialized conditions the crystalline structure of some metals and alloys can be suppressed and they form glasm These amorphous metals can be made from transition metal alloys eg nickel zirconiurn or transition or noble metals in combination with rnetalloid elements eg alloys of palladium and silicon or alloys of iron phosphorus and carbon see Amorphous magnetic materials Vacuum evaporation or sputtering techniques can produce thin films of amor phous metal elements as well as a wide variety of amorphous alloys 40 Liquid quenching at rates greater than 105 We is limited to alloys containing metalloids 41 Although glassforraing ability cannot be predicted with certainty a low temperature eutectic in a system of high melting metals often forms a metallic glass 4243 see also Glassy metals Metallic glasses are produced commercially as ribbons or fibers 504 pm thick and up to 25 mm wide The first success in this area was the Au4Si alloy quenched in liquid nitrogen Results since 1959 have shown that rapidly quenched metals are indeed glasses with unique propertiw Certain glassy metals exhibit soft magnetic anisotropy that may be controlled Strengths of metallic glasses are signi cantly higher than those of the crystalline forms but thermal instability often causm crystallization at relatively low temperatures Because of their noncrystalline structure amorphous metal alloys lack grain boundaries that tend to weaken conventional alloys or make them vulnerable to chemical attack Allied Chemical Co produces ironcontaining glasses that may be useful as rustproof steel coatings Structural methods such as xray diffraction 44 electron microscopy 45 Moesbauer resonance mm 46 and thermal analysis have been used to study the structures of glassy metals Heat capacity 50 quotquotquotquot l 7 Household and industrial m Drug and cosmetic 9 1 a Beverage ls g ff Food 9 39 5 3 quot 4 39 39 6 3 E I z 1 5 s 9 239i 353 30 E 395 I l i ll 39 quot393 s quot 39 39 1quot quot I I quot1 39 2 39 2 c 37 39 1 K 3 3 p 0 L I to was 7 A z1 2 39 f 324 39 so 129 Z Z A I940 I965 I976 1975 1930 Figure 35 Production and product distribution within the container glass industry domestic shipments Total production 10 r 1 1 a 1 l 1 1 I 1 l i 1985 1979 3975 Figure 36 Domestic production of berglass Flat Glass In the United States 31 atglass plants are operated by PPG lu dustries LibbeyOwensF ord llOFl Guardian Industries Ford Motor Company AFC Industries Combustion Engineering and The West Virginia Flat Glass Company imwth of this industry depends upon the construction and automotive markets The l39lnal Y 39 39quot 39 quot quot quot quot quotquot 39 I at t r m u uuumm glass or rolled and patterned glass Over 28 X 10 1112 of flat glass is consumed yearly Production of flat glass is cyclical but increases in volume by approximately 4 per year Less than 10 of the total used is imported The conversion of the industry to the float process during the 19703 caused con cern over the possibility of overcapacity but the continued demand by both the au tomotive and construction markets has allowed a relatively easy transition Float processing is very amenable to surface treatments that produce reflective coatings Because the cost of the glass represents a relatively small part 12 of the total construction costs the use of solarefficient glazes appears economical compared to more expensive mechanical heating or cooling equipment Solar energy qv conversion also represents a potentially large market for flatglass producers The solar collector or the solar reflector concepts which are now anticipated will require large quantities of high quality flat glass Conlaliicr Gino Statistics for food beverage drug and cmmctic and household and industrial containers are compiled and published by the Glass Packaging institute GP 115 Figure 35 shows the growth and distribution of glass container products Beverage containers including soft drink met wine and liquor constitute the largest rmment followed by food drug and cmmetic and household and industrial containers Approximately 85 of container glass is clear the remainder is amber Other tints make up a small percentage of the total There are ca 27 companies with over 120 manu facturing plants in the United States Most of these plants are owned by Owensdllinois Brockway Glass Anchor Hocking Glass Container Corp Kerr Chattanooga Thatcher and Indian Head glass companies Over 44 X 109 containers weighing more than 12 X 103 t are shipped yearly with an estimated value of over 4 X 109 Imports are of very minor importance because of high transportation costs Export of container glass is only about 1 of the total amount manufactured for the same reason Fmerglass Fiberglass is classified as either textile or wool More than a dozen companies produce textile fibers for draperies upholstery tires reinforced plastics paper and tape including JohnsManville Owens Coming Fiberglas PPG lndustriw Nicolibcrs and Reichold Annual prwuction of textile fibers is over 370000 t as shown in Figure 36 The annual production of glass wool is 12 X 10 t OwensCorning Fi Mrglas JohnsManville and others More than 80 of the production is used for building insulation the remainder for industrial equipment and pipe insulation Growth of the insulation market has been faster than the textile area because of the demand for additional insulation in both new and existing buildings Specialty Bass The pressedand blown or hollowware industry is comprised of over one hundred companies in the United States including Corning Glass Works Owensdllinois General Electric and Anchor Hocking The wide variety of products is divided into categories of pressed andblown glass for table kitchen art and novelty applications and products of purchased glass The latter consists of items for scienti c technical and industrial uses such as electrical and electronic products laboratory glassware optical and ophthalmic glass etc quotGlassquot in EC 1sted Vol 7 pp l75 206 by H G Vogt Corning Glass Works Glaasquot in EC lat ed Suppicment 2 pp 435454 by S D Slookey Corning Giana Works quotGlassquot in ECT 2nd ed Vol 10 pp ET Gm lw I H lluuuhin lll tlmi R V ilnrriruslon owing Glass Works 16 U10 r t ftgun lullllllulluul iul lluilIIIDhl lvId raw cn9 9quot9r gt4sJ r z Imltoogxogt L1lJ 3J J E Flrireon and coworkers J Noncryst Solids I7 129 1975 G W Morey The Properties of Glass 2nd ed Reinhold Publishing Corp New York 1954 p 23 Standard lefinitions of Terms Relating to Glass Products ASTM Standard 1978 ASTM C 16271 Part 17 1978 p 112 H A Davies Phys Chem Glasses l75 159 I976 1 8 Davies and P J Grundy Phys Stat Sol Be 189 97lJ Noncryst Solids lt179i939l2 D E Polk J Noncryst Solids 5 355 l9ll G S Cargill J Appl Phys 4 2248 1970 F G A Stone and W A G Graham Inorganic Polymers Academic Press Inc New York E962 G Tammann Der Glaszustand Leopold Vacs Leipzig 1933 H N RitlandJ Am Ceram Soc 37 370 1954 A Q Tool J Res Notl Bur Stand 3391 73 19416 N J Kreidl Glass lad 58 26 1977 D R Secriat and J D Mackenzie Glass Ind 46 408 451 1964 W Zauzmonn Chem Rev 43 219 1948 J N Gibbs in J D Mackenzie ed Modern Aspects of the Vitreous State Part I Butterworth loo Washington DC I980 pp 52457 A R Cooper and P K Gupta J Am Ceram Soc 58 350 I975 A A Lebedev Arb Staotl Opt Inst Leningrad 260 1921 J T Randall H P Rooksby and B 3 Cooper J Soc Gloss Technol 14 219 1930 N Vslenkov and E Poridioehitz Z Krist 45 195 936 B E Warren and I Biscoe J Am Cerorn Soc 2 49 2938 N Valenkov and E PoraiKoehita Z Krist 55 195 U936 W H Znchariasen J Am Chem Soc 54 3841 I932 R L Mozzi and B E Warren J Appl Crystallogr 2 K64 1959 Can H Xonnert J Karla and G A Gerguoon Science 179 177 I973 C Wright and A J Leodbetter Phys Chem Glasses 175 122 1978 H Doremus Glass Science John Wiley amp Sons Inc New York 1973 H Sun and A Silvermen J Am Ceram Soc 25 101 1942 E Milberg and C R Peters Phys Chem Glasses I8 46 1969 Chsudhsri and coworkers Phys Rev Lett 29 425 1972 3 Bray and J G O Keefe Phys Chem Classes 4 37 1963 L Mozzi and B E Warren J Appl Crystollogr 3 25 976 M Goldschmidt J Soc Glass Technol H337 1927 8 Sun J Am Ceram Soc 30 277 I947 Rswson Inorganic GlassForming Systems Academic Press lnc London l397 E StanworthJ Am Ceram Soc 53 6 I971 39 monks and 1 Ynmoaaki J Cerom Assoc Japan ll 215 I963 G Vail Soluble Siticates Their Properties and Uses Reinhold Publishing Corp New York I952 V I Avefyanov and E A PorsiKoshitn The Structure of Glass Vol6 Part 1 Consultants Bureau New York 1966 p 98 L D Pye and coworkers Borate Glasses Structure Properties Applications Vol 12 Materiek Science Research Plenum Press New York 1978 Ger Pats 63126 Aug 5 1978 and 62408 June 20 1969 W Herndorf C S Cowgill Ill NY Acad Sci 279 208 1976 H S Chen Acta Metoll 22 I505 I970 quot M H Cohen and D Turnbull Nature London I89 31 1960 M Marcus and D Turnbull Mater Sci Eng 23 21 1976 B C Gieasen and C N J Wagner in S Z Beer ed Liquid Metals Chemistry and Physics Marcel eliker New York I972 p 663 H A Davies Phys Chem Glasses l39l5 159M916 T E Sharon and C C Teuei Phys Rev B 5 3947 15372 S I Stookey and R D Mauer quotCatalyzed Cryutallizoticin of Gass 39l heory and Practicequot in P7087 in Ceramic Science Vol 2 Pergonwn Press 196i pp 7il G H Beall in L I Hench M S W Friedman eds Nucleation and Crystallization in Glasses American Ceramic Society I972 pp 25 261 3 3 88 3 3 8 3 3 3 3 3 935 Ei 383 V0 1 I umzaa om G H Beali and H l llittler Am Cerom Soc Bull 55 586 I976 J F Mec oweil and G H Heall J Am Ceram Soc 521 17 I989 I R Stewart quotConcepts of Glass Ceramicsquot in L D Pye and coeds Introduction to Glass Science I lenum Press New York 1972 pp 237271 T P Seward ill private communication Corning Glass Works S D Smokey Ind Eng Chem it 856 I949 S D Stookey G H Beall and J E Pierson J Appl Phys 49 51K 1978 A G F Dingwall and H Moore J Soc Gloss Teclmol 37 3amp6 1953 K E Hogy Electron Paclzag Prod 187 182 July l939l8 V 0 Attemoee Gas Permeation Through Glassquot Seventh Symposium on the Art of Glassblowing The American Scienti c Glaaablowers Society Wilmington Del I962 W C LaCourse quotThe Strength of Glassquot in L D Pye and coeds Introduction to Glass Science Plenum Press New York 1972 pp 45l 5amp2 W H Barney Corning Glass Works private communication and various Corning Glow public in formation bulletins 39 L L Hench and H F Schaokequot Electrical Properties of Glassquot in L D Pye and ooeds Introduction to Glass Science Plenum Press New fork 1972 pp 583659 J D Macilenzie quotDevelopment of Classes for Some New Applicationsquot Int Cons of Glass 1974 Ceramic Society of Japan Tokyo Vol 4 p 7 Ceramic Data Book General Electric Co Lamp Components Salsa Operation Cahners Publishing Co Boston Msss 1979 p 304 M J Minot J Opt Soc Am 8 515 1976 W A Weyl Colored Glasses Society of Glass Technology Shef eld Reprinted by Dawson39s of Pall Mall London 1951 J Wong and C A Angeli Glass Structure by Spectroscopy Marcel Dekker inc New York 1976 N J Kreicll Optical Propertimquot in F V Tooley Ill KJIfquotquotJ 86 Press ltelealea Feb 17 l9 15Sept l39 1976 P ehl39l 5977 May 19 I977 Nov t7 I977 l l iudualraw l1c Public Relations llepartment B7 1 A B l illcingtun Proc Roy Soc London A 314 1 1989 38 US Pat iTl2l86l6 Aug 29 1967 S M Doclrerly to Coming Glass Works 89 R F Caroaelli quotGlass Textile Fibersquot in H F Mark S M Atlas and E Hernia eds Man Made Fibers Wiley interocience Publishers Inc New York 1968 pp 425454 90 G H Machian quotGiana Fiber and Auxiliary Manufacturing Processesquot in F V Tooley ed Handbook of Glass Manufacture Books for industry Inc New York 1974 pp 715734 91 A l Andrews Porcelain Enamels The Garrard Press Champaign ill 1961 92 J A Pack quot aseMetal lnterfaceef and Bondingquot in J D Maclienzie ed Modem Aspects ofthe Vitreous State Buuerworth 8 Co Washington DC Vol 3 I964 pp 128 93 C W Parmelee Ceramic Glazes 3rd ed Cahuere Publishing Company Inc Boston Masa I973 94 US Pat 3231356 Jan 25 1966 J W Giffeu to Corning Glass Works 95 H A Mchdaater quotAnnealing and Tamperingquot in F V Tooley ed The Handbook of Glass Mama facture Boolca for industries lnc New York I974 pp 799832 A G Pincus and T R Holmes Annealing and Strengthening in the Glass Industry Magazium for luduatry inc New York 977 97 L H Adams and E I Williamson J Franklin Inst I90 597 835 2920 98 H R Lillie Glass Ind 2 355 382 U950 99 H N Ritland J Am Ceram Soc 37 370 1954 I00 Pat 3223503 Doc 4 I965 J C Fredley and G E Sleighter to Pittsburgh Plate Giana o 10 US Pat 3332762 July 25 I967 H A Mchlaater and N C Nitachka to Permaglase lnc I02 liS Pat 3468645 Sept 23 1969 H A Mchlaater N C Nitachke and J J Kawecka to Permaglam nc 103 US Pat 2306744 Feb 3 3938 H P Hood and M E Nordberg to Corning Glass Works 104 ASTM Standard Practices for Designing a Process for Cleaning Technical Glasses ASTM C 912 pt 7 I980 105 1 Holland The Properties of Glass Surfaces Chapman and Hall London 966 3 P C Schultz quotVapor Phase Materials and Processes for Glass Optical Waveguidesquot in Fiber Optics Advances in Research and Development Pienum Press New York 1979 107 G W Scherer and P C Schultz quotUnusual Methods of Making Glassquot in N J Kreidl and D R Uh menu eda Gloss Science and Technology Vol lll Academic Piece Inc New York 1979 I08 Fiber Opt Commun Newal l 8 Aug I978 109 G W Scherer J Am Ceram Soc 66 236 May E977 U0 US Pat 3737292 June 5 I939I3 D B Keck and coworkers to Corning Glass Works l I US Pat 3711262 Jan 16 1973 D B Keck and P C Schultz to Corning Glass Works U2 J C MacChcaney P B O39Connor F V DiMarceloJ R Simpson and P D Lazay paper 640 in Proceedings Tenth International Congress on Glass Kyoto Japan 1974 H3 J B MacCheaney i B O39Connor and H M Preaby Proc IEEE 62 278 2974 H4 J A Amiclt G L Schnable and J L VoaaenJ Vac Sci Technol 14 1053 1977 315 Annual Reports Glace Packaging Institute 800 K Street Washington DC General References Refs 25 8 and 33 are also general references L D Pye H J Stevens and W C laCouru ada Introduction to Glass Science Plenum Preaa New York i972 F V Tooley ed The Handbook of Glass Manufacture Books for Industry lnc New York 1974 Glass Industry Magazine Journal of the American Ceramic Society Journal of the British Ceramic Society Journal of Noncrystailine Solids The Physics and Chemistry of Glass DAVID C Bovo Davao A THOMPSON Corning Glass Works VDI I JLfJJ IItr nIuI U GLASSCERAMICS Gl SSCBl39a l39llCS are polycrystalline solids produced by the controlled crystallization of glasses They are primarily silicatebased materials that can be formed by highly automated glasmformiog processes and converted to a ceramiclike product by the proper heat treatment Glassvceramics which are also referred to in the technical literature as vitrocerams devitrocerams Pyrocerama Corning Glass Works sitalla slagceraraics and melbformed ceramics generally have a crystal content greater than 4050 sec Ceramics This excludes from the de nition other types of glass products such as uoride opals and copper ruby glasses which contain minor amounts of a crystalline phase see Gems synthetic Glass The liquidua temperature is a characteristic equilibrium temperature below which the liquid becomes thermodynamically unstable with respect to one or more crystalline phases Whether crystals will actually form is dependent on kinetic factors such as the rate of cooling of the glass and the growth rate of the crystal species In addition there must be a nucleation site from which the crystallization can start For most common inorganic glasses crystallization begins at the iuterfacial boundaries eg glassair glass refractory etc if they are exposed to temperatures just below the li quidua temperature for times generally on the order of minutes to hours This relatively uncontrolled crystallization commonly referred to as devitrification results in co lumnar crystal growth perpendicular to the surface which generally affects the prop erties of the glass product in a detrimental manner Since exposures to aubliquidue temperatures always occur during the normal glassrnaking process the glaaarnalrer has generally tried to make the glass formulations resistant to devitrification this is done by adjusting the glass composition to minimize the crystal growth rate in the glass working range Devitrification has been desc eozxfs or I T3333 gem I 1 54741we 39 1 K1 0 o J5 Pt639A 1 u E 220 lt39 5uHPvVa F E ado g 4 A a ax E us F VI cee H7 Decneasa gt Annealinr is the groper cooling treatment to ensure the relief of strains and stress within glass During annealing glass is held at a specific cf emperature the annealing point to allow the molecular structure of the I l as become fairly consistent Then it is regulated to cool at a rate 394 a dependent on the thickness of the glass and the extension properties of t39e glass being used The slumnina noint isa temperature above the annealing point at which glass will deform under its own weight Fusina occurs when the surfaces of two or more pieces of glass melt into one another enough to stick Batchin is the melting of various raw materials andor cullet recycled glass to a homogeneous liquid 8 W Devitrification the growth of crystals on the surface of glass which makes the glass appear cloudy or frosted Devitrification occurs from o o slow cooling between molten and annealing generally lOO u 3amp0 above the annealing point 23 avoid surface devitrification a basic rule to firing is to ease the glass to the annealing point and then ZIP up to the desired temperature Cenazeling fusing etc and then ZIP down to annealing allowing the glass to pass through the devitrification range as quickly as possible Once glass has reached the annealing point it is no longer subject to heat shock so it can be heatedas fast as the kiln will performto molten sq rom molten down t annealing the glass can be cooled rapidly by shutting o the kiln and opening it keeping careful watch on the pyrometer O H H I I 0 6 to cool below the annealing point and shock the flass he kiln is then closed and set for annealing and the correctcoolin cycle 1 inSn J39 HINT DEV NZ FLA r1on xA u j 5 4 I l 39TampWPE H7V E TME 22 ENAMELINC Enamels produced by L Reusche for firing on glass have a low maturing temperature Hhen fired properly the form of the glass is not distorted from the heat The enamels we use are 1o5o 1oeo F Drakenfeld Glass Colors 1o5o 1o8o F MB Series Glass Colors The mediums we use are Water base medium D1368 not listed in catalog but can be requested Elarco medium for enamels igou Reusche produces a wide variety of mediums for different applications of eamels ie silk screening spraying etc TO FIRE ENAMELS Follow appropriate firing schedule for the thickness of glass to be fired Vent kiln up to 3oo F to allow fumes from organic binders in mediums burning out to escape Once the annealing temperature is reached turn the kiln on High untill i3 reaches the maturing temperature for Drakenfeld Glass Colors 1050 1oeo F From our experiencg in firing three dimentional objects to turn the kiln on High at 25 below the annealing point works well to insure that the glass does not deform THEN as soon as the maturing temperature is reached turn off and open the kiln untill the temperature drops to the annealing point Turn the kiln on again and follow the annealing and down cycle of your firing schedule NOTE According to Dr Brill hed chemist at the Corning Museum IF the enameling temperature is below the annealing point of the glass being fired then the glass need not be reannaled before cooling To do so would heat the enamels higher than their range causing color distortion Since the glass never is heated beyo its annealing point it39s molecular structure remains stable Sgppliers LREUSCHE CO enamels glass paints mediums 2 Lister Ave special brushes catalog available Newark New Jersey 07105 201 5892o4o THOMAS C THOMPSON CO limited range of glass eanels 1539 Old Deerfield Rd nice transparents called ices P0 BOX 127 catalog available Highland Park Ill 60035 Soft Brick KILN TERMS a material able to resist heat high refractory materials Refractory withstand high temperatures insulating brick very light and porous of high refractory material Soft bricks hold heat within an area for instance a kiln interior These bricks do not retain heat they reflect heat Hard Brick fire brick very heavy dense brick of high refratory material These absorb and retain heat good for adding to kiln loads to slow heating and cooling cycles Fiber Blanket super insulating high refractory fiber material looks like cotton batting same properties as soft brick a does not absorb heat it reflects heat 39 iber Board same as fiber blanket but in the form of stiff boards ca ailn shelves and costs made of dense refractory material can be stacked to mcke more floor space for pieces in the kiln Like hard brick they absorb and retain39heat slowin down the firing process Kiln Hash a seperative painted on any kiln shelves or reusable molds that will come in contact with the glass so the glass will not fuse and stick on Kiln wash will not fuse to glass because it has such a high melting point FOREULA 2 alumina hydrate 1 kaolin SAND CASTING eld Formula s 9 sand wetonite Colored Glass Powders Kueglar Ponder CltampELLco 83 HOW TO FIHD AH AHKEALINS TEKPERATURE set two soft bricks l2 apart and place athin strip of glass accross it as thin as you can cut it Put a third brick shorter in height in between the two and under the glass strip 4 631 V n I Knowing the annealing temperature of glass to be in a range of 800lOOO F heat the test up to 800 and check it every 25 or so until you see that it has fallen down in the middle to touch the middle brick You can now determine the annealing temperature for this specific kiln and this I u out 1 Is specific glass as S0 less than the pyrometer reading Example If the strip falls while the pyrometer reads lOOO F then the c annealing temperature would be 950 F PYROEETERS Every pyrometer will read a different temperature unless callobrated by repositioning the needle to match a cone test for accuracy Cones are formulated to melt at specific temperatures and used primarily as temp erature indicators when firing ceramics It doesn39t really matter as long as it39s recognized that l500 F on one pyrometer may be read as 14500 on another Pyrometers are usually rated to measure the intensity of heat in both 0C Centigrade and 0 farenheit 0 2 r 427 800 538 1000 649 1200 820 1508 Coefficient of Zxoansion and Incomoatability of Glasses I 7 he linear expansion of flass must match closely that of any glass fused to it or it will break This restriction is ltf fundamental imtortance and very easy to understand If two glasses that are fused together expand and contract at different rates they are destoned to crack in order to relieve the set tension Stresses may break the glass at any time in the future if tension exists igrinr Schedules In determining a firing schedule that will insure proper annealing the thickness of the glass including a mold if there is one the coefficient of expansion and whether or not the piece cools on one or two sides are variables The enclosed table is conservative and labeled as ideal and it workse STRESS RELEASE AND ANNEALJNG 109 TABLE 4 SCHEDULES IDEAL FOR COMMERCIAL ANNEAUNGORDINARY WARE e F 56 C t0 Annecl point I 7 Strain paint 0393 Club Temperature 5039C 122 F 0 E Clishiei auoiiug ta 6 C below shah pt DCoolingnon 50 C Annoaiinq Poric u AHoming to 5 C when amoafme paint 5Held umpomhsro far time I E nal cooiiag Caeurlseea twside C39e3l5ngaaTvo SH met 5 m aha A I C D 3 A B C D E Ccof af 39 Gian K w C ibut r 3 Cool Cool Cos um T T coo CeaCaeF Rafe If T Rah Rate Rate Rafe T r Rah i Rate g Rafa C90 39 39 39CperquotCpor39Cpor C 39 39 C quot C quotC in Man Mia quot39 C Min Ms Min 39 t Mg 94 5 H 32 no 5 5 2 24 no mo 5 5 39 73 I 400 33x191 L 63 no is 30 3 5 so 130 15 to 2 24 no u g 127 s so 20 09 15 s so so 20 3 5 5 so 32 as 5 5 3 I6 as no 5 5 26 32 i zao sox 0 I 4 2 15 0 2 4 21 as 15 IO 3 as i as 5 127 s so 20 05 30 5 21 no so 2 4 39 21 3 32 so 5 5 4 a so no 5 5 4 23 no 9exm39 3 a H Is 10 1 2 It so 15 to 4 a so 5 27 3 so an 93 06 3 II no 20 1 2 1 g F 439 H 47 C V 7 C lt3 I I o53p 70gto gt7 U Q 0 Hi F C D 0 rx lt3 v 5 39 V 0 I0 T 0 AD 39 lt9 0 Q rv 0 m 9 8 Z D sgtaaio0 9wgta5 s The ancroximate coefficient of expansion for window glass and plate glass 397 is 8590 x 10 cmcm c 86 uman rt 1 I I rlrlnr ucieaules 39 4 quot J 139 1 In oetermn1ng a 1 35 schedule tat wlll znsnre pquotoper nquote l u tqe t39ickness of the glass including a mold if there is one the coefficient of expansion and whether or not the piece cools on one or two sides are variables The enclosed table is conservative and labeled as ideal and it works 543 C a 15 E Annealing point 538 C 13 Strain n0 3nt 4 y K 526 as C 4 ml 0 A B L C 1 l xmin EXALPLE Firing a sheet of quot plate glass cooling on one side On the way up A the glass can be heated ll Cmin Given the anneal ing temperature as 10000 or 538 C it may be brought up to 5 C above 0 X 49amp3 It should remain at annealing B for 15 min Tl5 During C it should drop 100 from the annealing at a rate of 1 Cmin 10110 Range 3 can cool at 2 Cmin taking 25 min so225 And finally Range 33 can cool at 11 Cnin to room temperature20 C This takes 41 min 58lle lh annealing in 49 min ll point falling below the strain point f if J sf DECORATIVE SURFACE TREATMENT Page Bl XI DECORATIVE SURFACE TREATMENT A TANK ATMOSPHERE LUSTERS l Atmospheric conditions in the tank can cause interesting and sometimes drastic changes in the surface of the piece you39re working on There are three types of tank atmospheres possible 39 a 0xidation clean hot burning flame too much air b Neutral slight bushy flame right on proper mix of gas and air T c Reduction heavy carbon atmosphere long cloudy flame caused by insufficient oxygen too much gas The most drastic changes take place when you are using glass that contains metallic oxides that will change color with atmospheric changes By generally firing with an oxidizing flame and suddenly changing to a reduction flame while you are working on a piece a surface luster will develop The most active oxides that perform this drastically are silver and copper This surface luster has no depth and will scratch off with some hard rubbing One pereent or more copper carbonate will produce a gooq7surface luster in a strong reduction atmosa phere Marvering silver on the glass will give a good silver luster 439 The glory hole can be used as the reduction atmos phere Since reducing is caused by inefficient combustion generallythe chamber will slowly cool The entire batch can be affected by a reduction atmosphere Copper red glass is produced by a reduction atmosphere firing a batch containing copper and a small amount of tin Two parts tin to one part copper FUMING The irridescent surface on Tiffany39s glass was sometimes achieved through fuming Basic fuming is simple to do while some of the more interesting surface colors caused by fuming are much more difficult to achieve fuming causes the release of vegy dangerous gases chlorine gas etc and care should be taken to vent the fuming area well Be careful of yourself and your neighbours flowers A good solution is to build a fuming chamber in the studio and vent it outside safely R Q iw DECORATIVE SURFACE TREATMENT Page 62 1 u Chemicals used in fuming stannous chloride copper39silicate copper chlorides iron chlorides potassium chloride strontium nitrate barium nitrate bismuth sub nitrate silver nitrate etc Techniques for fuming Dry and wet a Dry Step 1 Prepare the metallic salts in the proper proportion and mix dry Step 2 Place in crucible with long handle a tin can outside will do Step 3 Slow piece and while it s still hot almost finished Step HquotHeat crucible at tank door opening until smoke fumes are visible A small bit of hot glass on a punty placed in a tin can will also cause fumes Step 5 Place your glass piece directly in the fumes until it develops the proper luster Step 6 Reheat and place in annealer Some as people don39t reheat but take the piece directlyto the annealer P b Wet Step l Prepare metallic salts in proper proportions and crush in mortar and pestle 39 Step 2 Add to wet mediu Pure distilled water is common but will sometimes cause checking and small chips to fly off if sprayed Alcohol seems to work better since it evaporates very rapidly Step 3 Place mixture in pneumatic spray gun Step H Blow glass piece Step 5 While glass is still hot spray mixture directly onto surface do it under hood Step 6 Re heat and anneal The same basic procedure can be used for brushing on the mixture Just brush on the 0 solution instead of spraying it 80191 no DECORATIVE SURiACE TREATMENT Page 53 Stannous Chloride Strontium Nitrate Barium Chloride quotBismuth Nitrate Ferric Chloride Hydrochloric Acid Stannous Chloride FUMING FORMULAS Bluewgreen Blue over Redish over dark Strontium Nitrate 39 Barium Chloride Bismuth Nitrate Ferric Chloride Blue Red Opalescent 90 88 90 5 7 3915quot 5 l0 Regular over dark amber Opalescent glass 160 so 0 Mystic Gold Bluish 350 90 gm 150 5 gm ZIS gm 5000 ml glass glass 70 80 15 5 15 5 10 90 Maybe Blue 90 s 7 39w DECORATIVE SURFACE TREATMENT Page 61 fuming is a surface decorative treatment and should not be confused with the more complex Tiffany quotmetalicized glassquot quotMetalicized glass is achieved through the addition of rare metal salts directly into the batch By using an oxidation atmosphere until the very end and then switching to a reducing flame The reducing flame brings the metallic salts to the surface and upon cooling caused the deeper and rarer irridescence Then he may have fumed some after the reduction who knows PRBCIPITAIES Silver precipitates can be purchased from chemical supply houses or you can make your own fairly easily Dick Buss has experimented with some and listed below are a few 39 SILVER CHLORIDE AgCl Silver Nitrate ll2 gm Ag N05 Sodium Chloride 388 gm NaClReagent SILVER BROMIDE AgBr2 Silver Nitrate ll2 gm AgNO3 f Sodium Bromide 798 gm NaBr2 SILVER IODATE Agl 39 Silver Nitrate 112 gm AgNO3 Sodium Iodate 90 gm Nal Step I weigh materials keep separate Step 2 Dissolve separately in distilled 39 water Step 3 Pour together into one container Step H Stir precipitate Step 5 Filter throw liquid away safely Step 6 Squeeze precipate until no more liquid g I Step 7 Dry precipitate Step8 Use small amount to give luster you need good heat and heavy reduction 92 03 quot Fz y 12 1rJL7g3 Lohtetm GLASS w w gE 9rjn Glass Color is formed in glass when particular elements either in an ionic state or in thei elemental state interfere with the transmission of light through a sample of glass in such a way as to allow certain wavelengths to pass and restrict the passing of certain other wave lengths For instance in a chromium glass all wave lengths of light are absorbed by the glass except thosewavelengths which appear in the green range to the human eye thus giving the glass agreen appearu anceo There are several important factors involved in producing a colored glass These are 39 1 Concentration or amount of colorantused 2 Chemical composition of the baseglass nearly all colorants have a favorite environment 3 Atmosphere ingthe melting chamber A color range for most colorants can usually be produced by varying one or more of the above factors we shall consider than Colored glass formed by the ionic or elemertal state of cer tain metals Ionic Colors 1 ronuthe ion ratio of Fe 2 amp Fe 3 determines the final color of the glass Fe 3 is nearly colorless so an increase in the oxidised state of the glass will produce a lighter green while a reduced state favors the Fe 2 ionwhich dill produce adark blue green color 39 2 Kancanese The ion ratio of Mn 2 and Mn 3 determines the findc0l0r of the glass Mn 2is nearly colorless so an increase in the reduced state of the glass will produce a lighter purple while oxidising conditions favor the Mn 3 state which produces a deep purple when potash replaces soda in the base glass more purple less brown glasses are produced 3 Cobalt Cobalt glassesare unaffected by changes in oxidation and reduction Cobalt is a very intense colorant with as little as Gl producing a rich blue Potash improves the color and cobalt is often used as an ingredient of black glasses because of its intensity h Nickelna little more nickel than cobalt is needed to color a glass but not much In a potasu glass a purple tint results in a soda glass the color tends toward brown or yellow Nickel is not affected by funrace atmospheres but is somewhat affected by the enyironment provided by the base glass 4 Co er As an ion copper producesa typical greenidu blue The base glass 1 should be of an oxidizing nature as should be the furnace atmosphere 6 Chromiuma deep rich green is produced in most glasses with chrome Chrome is not as soluable in glass as other colorants Under extreme oxidation or in high alkali or lead content base glass the color will tend toward yellow 3 2 v MEL NE L4M 7 Uranium Produces a yellowuyellow green glass D 8 VanadiumProduces a yellow to green tint in most glasses 9 NeodyxrriumProduces a pleasing pinkpurple glass 39Dc3 9 9Ce amp unit 6 I Lj Coloration by Metallic Elements 1 GoldThe characteristic gold ruby is formed by the elemental gold crystals in the base glass Upon reheating the glass will strike that is the crystals grow larger and become more appareit 2 CopperIn the elemental state copper precipitates out of the base glass the resulting crystals producing the characteristic copper ruby and striking the glass intensifies the red The base glass should be of a reducing nature as should be the atmosphere of the furnace and the addition of certain ingredients such as tin aid in the production of the color 3 ilverA pleasing yellow is produced with silver A reducing situation is favored Coloration by sulfer cadmium and selenium 1 ul grgBy itself sulfur has little coloring ability but when used with carbon a yellowamber color is produced A reducing situation is required Sulfur is ale essential in cadmiumsselenium glasses 2 Qadniunfwhen39cadmium sulfide is added to a glass a bright yellow is obtained upon quotstr ingquot A reducing situation is favored 3 Seleniwmpcoapounds of selenium are formed in the melt which produce a light pink in a potash glass The color tens toward orange in a soda glass Slightly a reducing to neutral conditions are required h Cadmium Seleniumrubya anges from brilliant red to orange are produced by vario mixtures of these chemicals The color Wstrikesquot and axiightly reducing to neutra situation is required Einc aids in developing to color Almost any color may be obtained by using the above colorants or combinations there KL1d 1 288 ABRASIVE BLAST TECHNIQUE by Dan Fenton Abrasive blast technique is basically simple and straightforward requiring no sophisticated tools only some ingenuity and maybe a couple of cheap tricks The most common problem is how to get the work blasted once it39s ready Many glass retail and production shops now have sandblasters If there appears to be none in your area look in the Yellow Pages under monument makers automotive machine shops and automobile customizers If you lmk under sandblasting you will probably only find industrial contractors who are willing to tackle no job smaller than the entire exterior of your house If you live near a boat yard you39re likely to find someone there who can help you out The following is a list of basic terms These will all be explained in detail later on tch To abrade a glass surface 6 achieve a design using a stencil for control 39 o t To lightly abrade a glass surface area for light diffusion sometimes referred to as poor man39s opaque or to provide a rough end surface for glue chipping 1 Carve To blast deep into the glass at various depths to create 3dimensional relief gQ To blast all the way through theglass to make holes or otherwise impossible shapes This can be done on flashed glass by carefully blasting part way through the flash using light pressure and ne sand RESIST MATERIALS 3M Maskoff 280 pressure sensitive tape This is excellent for fine detail etching and is available in widths from 4 to 24 250 and 270 are also available They are lighter but will do the job just as well 125 Two layers of cmmon masking tape This is a good substitute for Maskoff and works quite well for light duty etching Contact shelf paper Actually this is a sheet acetate and is available at any hardware store The clear is best because it39s slightly stronger It is good for detailed etching and since it39s clear the stencil cutting can be done directly from the drawing eliminating the need for tracing and transfer 3M Butternut 507 sandblast stencil This product is made spedfically for heavy duty work such as carving and cutting Buttecut is excellent for limited production etchings since it can be transferred and reused a good number of mes Vinyl auto upholstery material This may not be any cheaper than buttercuti but it may be easier to get hold of and it does act as a reasonable substitute Investing in a can of spray adhesive isn t such a bad idea ather Innertube rubber This is excellent for production etching tenplates It39s more difficult to cut the stencil than ibuttercut but it holds up in production much better A Pierced metal tanplate This is definitely for high volume production of simple etched designs A nonferrous metal such as brass is better since it is softer and will not wear as fast If you want a really bornbproof template cover it with buttercut A slight bit of detail may be sacrificed but the tmnplate should last forever 3M 2 sandblast stencil filler This can be screened on for a very light frost type of etch It can also be applied with a hypodermic needle for ne wavy lines and dots A light pressure and ne sand is necessary in the blasting White glue This will act as a good substitute for the above mentioned stendl filler if availability is a problem 126 quotOpen weave cloth If you need to directly reproduce the pattern of an open weave fabric such as lace the fabric itself can be used as a tanplate Soak it in dilute white glue place on glass let dry and blast using low pressure and fine abrasive The primary tool used in the graphic preparations for abrasive blast art is the knife Most of the cutting is done at the very top of the blade so a blade design must be chosen that will afford maneuverability and stay sharp at the same time I still haven39t found the ideal conabina on I use an Xacto 11 because of the maneuverability but the tips seem to break off much sooner than they get dull Many people prefer a swivel knife Xacto makes a gmd one at a reasonable price If you want to go for quality at a higher price there is the MCGIaw Color Graph available through screen process V supply houses Another tool that always comes in handy is a light table Light tables are really helpful for tracing stencil cutting when using a clear resist and working amprectly from a drawing and viewing finished work If nothing else you can always use it for a surface on which to cut your glass TRACING AND TRANSFER OF DESIGN Let39s assume that the design to be etched is on paper The next step is to transfer the design onto the surface of the resist material Masking tapes will take pencil lines drawn mrectly on as well as standard carbon paper transfer Inner tube rubber will also accept carbon paper transfer but since the material is dark it may be difficult to see the line To make the traced line visible sprinkle nely sifted whiting onto the surface and gently blow off excess The whiting will stick to the greasy traced line making it more visible Other resists especially buttscut will accept a direct pencil line transfer burnished on from paper 127 It is also mportant to note that the blasted image usually looks better when viewed from the nonabraded surface This is especially true with deep relief carving This means that the design usually has to be reversed before being transferred onto the resist CUTTING THROUGH THE CLASS Abrasive cutting all the way through the glass allows one to create shapes that are impossible with a glass cutter and to make free form holes that glass of other colors can be set into thus giving a oating effect without any extraneous bad lines In order for the inset piece to fit close a clean edge is needed The most efficient way to achieve a clean out is to mask off and blast from both sides Blasting through from just one side leaves a are on the other edge of the glass and is rather difficult to remove See Figure 1 The procedure for cutting the resist so that the mags lines up on both sides is as follows 1 Apply ibuttercuti to both surfaces and trim to the shape of the glass 2 Cut paper template to the shape of the glass Tracing paper best 3 On the paper template draw the perimeter of the area to be cut away 4 Turn over the paper template and trace the shape on the reverse side 5 Place the paper template on the glass carefully lining up the edges all the way around and rub the pencil lines with a burnisher The pencil lines Y transfer onto the surface buttercut 6 Do the same on the other side If all steps are followed carefully the shape will match bcation on both sides after the masking is cut away 128 a5 9 5 mm W mommgr wt Figure 1 BA EC emuM m amtkw GMgs Gama mmaxrue w EASTN6 wrmmo mes runquot BD P wwu rtF5 ts awn Figure 2 129 If you have a variety of abrasive grits at your sposal use a fairly coarse one like 60 or 30 This will allow faster wtting with less heat build up ma friction When copper foiling the inside edges of mail holes you will note that it39s almost impossible to get the foil to cooperate Try using copper wire on the glass surface instead This will do the same as the foil in that it is something for the solder to adhere to It39s best to pretin the wire to avoid excess heat nansfer to the glass ABRASIVE ETCHING ON FLASHED GLASS Flashed glass is a multilayered glass usually handblown that has one or mre thin flash layers of darker color over a thick base of lighter color This thin flash can be rmoved in selected areas by abrasive blasting to give a duotone effect In cutting ashed glass it is necessary to determine which ads is flashed since it is usually cut on the base side If the etching modus operandi is to produce the duotone effect then the resist must be applied to the flashed surface Following are several ways of nding the ashed side of the glass 1 Look at the seeds in reflected light If the edges of the bubbles show up lighter and a different color than the light transmitted color of the sheet then you are looking at the base side 2 If there are no seeds in the sheet take your grozing pliers and clamshell one edge then turn over and do it to another edge on the other side The duotoned clamshells indicate the ashed side 3 If you happen to be working with a glass that has a thick flash such as English you can look at the edge and actually see the flash The graphic potentials in flash etching are vast and the intricades of detail attainable can be amadng When getting into extreme detail work it is important to have very clean cut edges on the resist Any 130 small blobs of excess adhesive will inhibit abrasive action and make more mtensive blasting necessary thereby reducing the crispness of the edge As a general rule sharp line accuracy will be maintained as bng as the line is at least as wide as the ash is thick There are exceptions to this of course and most of those lie in the thickness of the resist material The thinner the resist material the more detail is possible The only problem is that the thinner the resist material the faster the wear along with the likelihood of edge lifting See Figure 2 p SHADING ON FLASHED GLASS Shading in this contmt means creating a tonal gradation that moves smoothly across an area changing from dark flash to light base Those halfquot tones those areas where part of the ash is eventually abraded away are achieved in the same manner It is difficult to mzplain just how to achieve these results because a good deal of care and sensitivity is necessary Following are some helpful considerations Blast with a low pressure and as high a sand volume as the system will allow without clogging The pressure pot system is excellent for this kind of control The nozzle size depends on the amount of area to be covered A small nozzle will give more system control due to more back pressure but requires a more skillful hand manipulation for a smooth gradation of tone Keep a separate stash of abrasive for this kind of work 150 or 200 is ideal 100 will work quite well as bng as it hasn39t been used for any other kind of work If the same abrasive has been used for heavier work it is likely that it contains larger glass particles that have fallen off previous work This will result in pitting 131 Carefully examine the flashed surface of the glass to be worked and avoid any seeds near the surface This will cause large spots of base color where half tone is desired Fischer glass has a mderately thin and very controllable flash but an overabundance of seeds near the ashed surface HartleyWood has an extremely thick ash which sews like it should be easy to control but the ash thickness varies and is unpredictable St Gobain glasses are usually thin to moderate in flash thickness but there are almost never any seeds near the flash surface There are also no surface striations on the ashed side which makes the St Gobain glass best for shang and ha1ftone work RELIEF CARVING Relief carving can be done in thinner flashed glasses This technique is never really at its best unless done deep into a thick glass of at least 14 inch When viewed fxan the back side the depth of the carving is magnified and if it catches edge light the carving will appear to be self illuminated The technique isn39t difficult but it does require some preplanning First determine where the deep cuts are to be They are usually the most accentuated lines in the composition Remember that you are working backwards and the deepest cuts will cme forward when the finished product is viewed Blast your deep work rst to the depth that you want it It probably won39t get too much deeper in later blasts but it will round out See Figure 33 Subsequent depths are achieved by remving e sting resist material acoor ng to the design schenatic and lasting again This is repeated until you arrive at the desired effect Figure 3b Make sure you use a heavy duty resist material such as ibuttercut since it will undergo considerable stress in this process 132 91 52 g A Swmwr M award OW V Y B 9 iv 1 am QASS Figure 3 133 REANNEALING CONSIDERATIONS All sheet glass has been annealed at the factory but there always remains some residual stress Some glasses will have more tension than others depending upon the annealing treatment and the chemical composition Upon cutting into a sheet of stressed glass recognition is usually not a large problem for most glaziers for rather obvious Do not try to recover your bases by using such glass for Your efforts will be better spent writing abrasive letters to the importers Now that you have found the piece of vitrious stock that shows all reasons abrasive blast work of the qualities of being a fine candidate for the job don t forget about tensions When the surface tension is broken and the internal cohesion is interrupted due to abrasive blast interference then certain problems will becme magnified resulting in heat fractures under the soldering iron and spontaneous Just at what is a matter of personal judgment are likely to arise Existing internal stresses sunshine fractures point the work should be annealed Following are several considerations if the work is large 2 square feet or more if it has been extensively worked that is carving if the glass shows signs of internal stress extreme thickness variation If it is determined that a piece has to be reannealed here s how to do it After all abrasive work has been done place the piece in a hln and bring it up to about l0O0 F Keep it there for about 20 minutes It is likely that an electric kiln will be used and in that case is bring it up to tmperature and turn it off hold heat quite well does that means that your pyrometer is bad or much cutting and warping and all you have to do Electric kilns usually work melting If it your local dealer sold you a bogus product Do and lowering the tmperature between 200 600 F of therxnal shock susceptibility Don39t worry about your take care in raising This is the range 134 onnunv39upn u 03 Garnet ABRASIVE MATERIALS This is an importanticonsideration if you39re considering building you own abrasive blast system If you are contracting out your work this information is still important The come in various grades 60 to 80 39 for cutting A a coarser grit l0O for most etching and carving l50200 for shading or use with screenedon white glue or stencil filler 39 i The abrasives are available in various qualities Crystal silica 39 This is the most easily obtainable and the cheapest About 350500 per cwt good in a nonrecovery system It wears out rather quickly but is Iron oxide slag This costs about the same as crystal silica but seems to last longer This gives fairly long lasting sharpness but does wear out It serves as a good compromise between beach sand and expensive About 1400 per cwt I cannot give an accurate report on this since I ve That is not to say that it isn t effective I hope it is at 50 to 60 per cwt it had better be This is the shiny black Cadillac of abrasives faster holds its sharpness longer and costs more about 80100 abrasive Aluminum oxide never used it and I don39t know anybody who has Silicon carbide It cuts per cwt than all others combined Expensive but worth it It will never get dull only finer they stay sharp because they will fracture cleanly along lines of 39 that are crystalline molecular cleavage determined by the structure U awn Wamp quotI C 5 8 3Rg2 E 4ua 53 at 1n3eK 135 alokmoa 3 thereby always maintaining the same shape and edge Less heat is generated from friction with When the particles break apart 39 y This is used for smoothing out the texture left by the It doesn39t result in anything that come close to a re polish but it does rwove agood deal of roughness Ground walnut shell This is said to serve the same function as glass beads but at a fraction of the cost abrasive A POSTSCRIPT T0 ABRASIVE BLAST TECHNIQUE BY DAN FENTON by David Spildie RESIST MATERIALS Contact shelf paper This comes in two grades AZ1 It is felt that A21 is better stronger stickier and clearer Liquid Latex This is a good resist for low pressure frosting The advantage to this material is the fact that it can be painted on and then wiped or cut back from the project RELIEF CARVING LIGHTING POSSIBILITIES After the piece has been frosted or blasted it can be lit from many angles for different images One very dramatic effect is to light frm the bottom This particular technique will also work with plate glass of various thicknesses except for ABRASIVE MATERIALS Aluminum onde This material lasts longer than silica It will stay sharp as it breaks down It can be purchased for about 5000 cwt direct ampm an abrasives sales house Solar greys and bronzes 136 Z05quot Regular and 0 f Section Safety in working with glass Few materials are as unjustly maligned as is glass as concerns its safety When the word glass is mentioned many people have visions of sharp edges cut fingers biood and other gory details The fact is most people go through a whole lifetime of using glass everyday drinking glasses eye glasses window panes light bulbs mirrors watch crystals etcand never experience a single injury as a resultof the association Glass when handled with a minimum of care is no more dangerous than dozens of other materials we use daily The only time glass becomes a potential danger is when it is involved in a mishap Such mishaps are rare and are almost aiways a result of negligence that could have been avoided The fear of glass is a characteristic of the raw novice alone Anyone who has ever had a small experience in handling glass soon loses any fear of the material Following are listed some of the suggested precautions that should be observed when working with glass 1 Maintain Good Housekeeping Practices Most glasses wiil break when hit or pressed against hard obiects Keep the area where you are going to work on glass cleared of unnecessary hard objects and Fig 23 A glass sting for carrying large sections of A glass Requires two men Courtesy Sommer and Macro Glass Machinery Co Fig 22 The ThirdManquot sling enables one man to manage a large section of glass Courtesy Sommer and Mace Glass Machinery Co materials Store glass against a smooth even surface avoiding edges and protrusions that might touch the glass in one small area A table that is to be used for glass work on frequent occasion should be covered with an old carpet or thick felt On a temporary basis the tabie could be covered with a pad of newspapers ln any case the table should be kept clean of all accumi ulation of any kind this includes glass chips it is a good practice to brush off the table with a counter brush after each time giass has been cut on it 2 Avoid Raw Edges I There are two times when there are sharp quotraw not ground or polished edges on giass first when it is cut secondly when it is broken The bare skin should not be pressed orrabbed against such edges at any time When carrying a small sheet of glass with raw edges grasp it at the top of the sheet with the thumb and first finger making sure the raw edge does not touch the skin between the fingers When a heavy sheet of glass is being moved about and must be held at the bottom protect the hand by wearing a glove with a rubber coated palm or usea NonSlipquot rubber hand grip which is a piece of rubber 7quot by 7quot by l8quot thick Fig 23 Vacuum cup holder for lifting glass Courtesy Red Devil Tools that is folded over the raw edge When moving a large piece of glass that you estimate to be beyond your capability of handling alone secure some assistance Never take a chance and move it by yoL39rs elf as the results can be very destructive There are a few different devices available that can be used to carry about large pieces of glass One is the Glass Sling Fig 2l which consists of a strong belt about50 inches long by 4 inches wide with handles on both ends Two people hold the handles on the ends of the sling while the glass is cradled on the belt be tween them A device called a ThirdMan Slingquot Fig 22 is a unique type of sling that enables man to carry safely a maximum sheet of glass The Vacuum Cup Holders Fig 23 are safe lifting devices positively capable of holding as much weight as any strong man can lift they can be secured in single twin and triple gripsquot The vacuum holder is easy to operate simply place it on the clean dry surface of the glass and push down the lever The Glass Lift Tool Fig 24 enables a man to lift plate glass from ground level directly into any moderate height bulkhead and onto a setting block without the use of fingers straps or vacuum cups The entire device is rubber coated except for the handle Jo e 5 IG5 g 5 9 6 5 39 s 33 583 Fig 24 The glass lifting tool enables a man to conveniently lift plate glass Courtesy Sommer and Maca Gloss Machinery Co 3 Handle Broken Glass With Care Broken glass requires care in its removal as the edges are usually knifesharp lt ls best if gloves can be worn for such an operation Proceed by removing the largest pieces first then work on down to the snnal est pieces The smaller pieces can be picked up with a pair of tweezers These small pieces are sometimes hard to find Resist the temptation of feeling around for these pieces with the bare hand lt is far better to use a brush or broom to sweep a large area around where the glass was dropped 4 Avoid Touching Fired Glass Heated glass does not change in color or shape until it has been subjected to very high temperatures There fore a tired heated piece of glass can look perfectly normal and still have sufficient heat in it to inflict a disturbing born When firing glass it is best to use spatulas tweezers and similar devices for handling the glass lt is also good to wear asbestos or even regular work gloves as there is always a temptation to pick up and inspect a tired piece before ithassufticiently cooled Cutting glass Section 3 Fig 3 The tools needed for cutting giass aresimpte and few Courtesy LibbyOwensFord Glass Co In the Middle Ages glass was cut with a too which was nothing more than a sharply pointed rod of iron heated to a high temperature The red hot point was drawn along the moistened surface of the glass causing it to snap apart The fracture was not very accurate and the rough piece had to be chipped or grazed down to the exact shape with the help of a hooked tool coiled a grazing iron The present day Steel Wheel Cutter which is almost universally used was invented in 1869 by Samuel Monce in Bristat Connecticut The term glass cuttingquot is rather rnisieading as the glass cutter does not actually cut the glass it merely fractures the surface upsetting themolecular structure which causes the glass to part along the scored line The whole trick in cutting glass is the making of a clean sharp score to a uniform width and depth through out the length of the cut This is the single requirement for the perfect glass cut To accornpiish this careful attention must be given to a few simple details THE EQUIPMENT NEEDED The Cutting Table Choose a firm level flat topped surface for the cutting table Thirtyfour inches above the floor is no good work ing height for the average student Make certain that the lighting is good and placed well above the line of sight Cover the work table with soft felt or a piece of deep piled carpeting A covering of this type prevents the tiny glass chips from previous cuttings from marring or scratching the glass as it is slid around while making the cut A hard surface holds the chips tight against the glass causing scratches In an emergency or for occa sional cutting a flat wad of newspaper could be used The soft felt or carpeted tabie top has the extra advan tage of giving slightly under pressure This allows the glass to bend when pressed down on after making a cut helping to runquot the cut A whisk broom should be kept handy to sweep the tabletop clean and free of chips A commercial table is shown in figure 32 This table is made of steel and can be raised lowered and tilted for conveinent handling of glass Fig 32 Tilttop cutting tabie in flat position Courtesy Sommer and Mace Glass Machinery Co The Straight Edge A good straight edge is needed as a guide in cutting straight lines and it wiil speed up the operation For this purpose glozier s rules Fig 33 as well as the Glass cutters iquot and quotTquot squares Fig 341 are used dad 5 exlru as with improved type substanna ltfgavrglcust brass P l quot39 Fig 33 Glazier s rules Courtesy Sommer and Maca Glass Machinery Co These are usually rnade of selected hard maple thor oughly kiln dried and graduated in US inches For cutting wtndow glass accurately and uniformly to size a glass cutting board complete with adjustable straight edge Fig 35 may be used These are made in sizes from 24quot X 36quot to 48quot x 72quot of narrow strips of well seasoned tumber and ruled in inches both ways Where the above are not available any good yard stick or straight and true ptece of wood or metal will do as a guide Should the student have trouble with the straight edge slipping while the cut is betng made he can overcome the trouble by dampening or placing strips of friction tape on the bottom side The Glass Cutter Fig 36 Use a good cutter The best is inexpensive and a good iob cannot be done with a poor one Fig 34 Gtass cutter39s Lquot and Tquot squares Courtesy Sornmer and Maca Machinery Co 39 a as39 5s 9 I R at it I Em A 615 CUTTING GLASS s H O IIununIn5s quot39 V Q1 Z x 5 0 K K mnnnuuuunu E ease P e Witsllllill Q s1nIi I I E l39 IIIII K l l39 5 quotI ampIII tt uw tcx BIIIIIII II use unnnuuunI a1 gpg nu 39 p7 39 39 guxn ta quot Fig 35 Glass cutting board Courtesy Sommer and Maca Glass Machinery Co Cutters employed everywheretoday are the hardened steel wheel type made by a number of manufacturers Figure 37 A through H shows many of the popular types Cutters A and B are the types used for general cutting Cutter 8 has the ball knob that is used for topping the bottom of the glass otter it has been scared Cutter C is the type wherein the wheel can be replaced when it gets dull Both D and E have turret heads with six separate cutters As each wheel gets dull a new one can be rotated and tacked in place When all six are dull they can be replaced with a new turret head Cutters E and F both have a wooden handle which is preferred by many glass cutters because otfits larger grip The magazine refill wheel glass cutterlshawn in G carries Fig 345 A sharp cutter is of prime importance Courtesy Libby OwensFord Glass Co suw3 o I2 e THE ENCYCLOPEDIA OF WORKING WITH GLASS f n n J E le Figzquot3397 Various types of giass cutters six extra wheels in reserve in an extra heavy ball head when a wheel gets dull it is easily slipped out and a new one slipped in In H is shown how many of the better glass cutters are packaged in a plastic tube This tube or quotCaddiequot is kept as a protective constant storage for the cutter when not inluse The wheel of the glass cutter is the all important part Th39e ordinary type is made of very high grade tool steel carefully ground balanced and axled When properly lubricated and maintained it can give a long period of satisfactory service Within the past decade carbide wheels have come into rather popular accep tance Utilizing tungsten carbide long recognized as one of the hardest metal known to manquot these wheels permit a relatively longer life than the standard steel wheel and offer certain advantages in use greater penetration in cutting and greater ease parting the glass after use ofthe glass cutter At the time the first steel wheel glass cutter was in vented in I869 glass manufacturers produced mostly plain flat glass which was used primarily for windows Great progress hastaken place over the years until now Fig 38 Biamond glass cutters Courtesy Sommer and Maca Machinery Co we have hard glassquot soft glass heatresisting glass In thick glass thin glass decorative glass and countless other varieties With these many variations it becomes necessary to change the penetration action of the wheel to compensate for the difference in the structural com position of the glass This is accomplished by varying the degree of the bevel which produces a progressively cutquot A soft glass such as plate glass requires a duli cutting while theharder glass requires a sharper wheel II sharper or duller There is also a reason for the difference in cutter wheel diameters The great majority of wheels are 732quot in diameter The pressure of the wheel as it rolls over the glass has a bearing on the penetration and there is a ratio between the pressure and the arc of the wheel that is important With average hand pressure the 732quot diameter wheel gives best results For a duller wheel on soft glass a slightly different pressure is required This is compensated for with a larger wheel V4quot in diameter making itunnecessary for the operator to change the hand pressure The smaller wheel I8quot in diameter is used for cutting patterns andfor cutting circles Here the wheel with a small arc is necessary to follow curved lines without dragging Care of Wheel Cutter The wheel cutter should be kept in good condition by immersing it in oil when not in use a mixture of one part light oil and one part kerosene is recommended This prevents rusting keeps the cutter clean and makes certain that the wheel will turn freely on its shaft at all times Pocket and table containers can be secured that are made especially for this purpose A clean I32 gallon paint can with cotton or rag in the bottom and just enough oil and kerosene mixture in the bottom to cover the cutter wheel makes a very fine permanent holder for thecutter Treat the cutter with respect it should not be thrown downland forgotten until the time carries to use it again Use a sharp cutter There is no economy in trying to work with a dull one When a nomrenewable cutter has become too dull for further use destroy it Fig 39 Daimond glass cutter particulariy good for novice Diamond Glass Cutter Fig 38l Diamond glass cutters are usedto a very limited de gree These cutters depend on a hard commercial dia mond embedded in the head to do the cutting The diamonds are ground to steeper or broader angles for cutting hard window glass or soft plate glass The dia mond glass cutters are preferred by some experienced glass cutters because of their long useful life span and the ease with which they trace odd shapes They are however extremely expensive and hardto control and therefore not recommended for the inexperienced ln figure 3 is shown a type ofdiamond glass cutter that can be used by the novice with a degree of success The proper angle at the diamond is set in this tool and it is only necessary to hold it in the manner shown to obtain the best results The Glass Cutting Machine Where a great deal of straight glass cuttirig is to be done a cutting machine can prove to be most worth while Fig 3l0 These machines are designed to as sure fast proper performance for all types of glass cutting to close tolerances Fig 340 Glass cutting machine used where large quantities of fast accurately cut giass is needed Courtesy FletcherTerry Co iii CUTTlNG GLASS s l3 C ut Break Fig 3 l Giass cutting gauges Glass Cutting Gauge When several narrow pieces of glass are to be cut parallel with the edge a glass cutting gauge may be used Fig 3H The gauge can be quickly adiusted tram 3l6quot to 33939 It also includes two breaker openings for thin and thick glass Glass Pliers Glass pliers Fig 3l2 are used for breaking off nan row strips of glass They are also used for nibbling away unwanted small pieces of glass that have remained from an improperly executed break 3EETlquotlFlT HOOK Fig 31 2 Glass pliers 2quot I4 e quotTHE ENCYCLOPEDIA OF WORKING WITH GLASS Eo I tie HOW TO CUT STRAIGHT PIECES OF GLASS l Rest the glass on the cutting table or 2u layers of newspaper and clean it with D a clean rag Get rid atoll dirt or film I z which would prevent the cutter from P x mcikinga uniform cutManyglossworllt ers quotwipequot kerosene across the lineta 55 f be cut with o sottbrushihis eliminates much at the flaking from the cutand I g 33913 reduces the tendency for the cutter to slip The kerosene should be wiped off of the gloss otter making the cut as it hides the cut mark M Fig 313 Courtesy Red Devil Tools 2 Lubricate the wheel at the cutter using any light household oil such as 3in Fig 314 I Dipping it in o mixture of one port light motor oil end one part kerosene is ideal Fig 344 Courtesy Red Devil Tools I Fig 33 5 Courtesy Red Devil Tools 139 3 Place the straight edge along line to be cut to guide the cutter It the bot 39 Fig 315 tom side of the straight edge is damp ened it will stay in position without slipping I5 CUTTING GLASS e ma 4 J A W M We wax mwmwv 2 M LibbyOwensFord Glass Co Fig 336A Courtesy Red Devil Tools Fig 3168 Courresy 4 Hold the cutter correctly beiweemihe first and second fingers wiih ihe thumb on the underside of the handle as shown in photograph Do no hold i 999310 Ixea unn OFI HO m noh mIGee mo mh moeem r S wedwe In IvH nined e Qtn xuu Ymhtme maemsm OamFhrnm S Och n3 eneiw F U Pnmcmm 0 g S wnmmmm m e G TSSIDQ r z m fmesm oiemam O IU GgCG Fig 316 AampB Courtesy Red Devil Tools ig 347 F mme fie ne 0 w m eh nHr G smfr SW3 muum wmm fol mm r xmoo ianwrl mi 0Y Y ID n eew Gc 5 Do not hold the cuiier on an angle am we Woo 8 2 n oh is as mm U En mm mm ii cuis poorly siroighi even ihe whole surface and the gloss Fig 3 I 7 off the edge of Practice on pieces of scrap 0 io get the feel 16 THE ENCYCLOPEDIA OF WORKING WlTH GLASS Cutting Patterned Gloss Patterned glass should be cut on the srnoothest side with an evennot heavy pressure Be sure the cutter is lubricated with kerosene end oil mixture mentioned above Thus on C pattern like Doublex Fig 320 the cut should be on the side where the pattern is rounded on textured Ranclex Fig 32l it should be on the peb bled not the grooved side Further do not cut along a groove the cutting wheet may get stuck if the groove Fig 3 l8 Courtesy Red Devil Tools is uneven For a smooth pattern a sharp cutting wheel should 6 To break the glass hold it firmly on be used as on clear glass fora rough pattern on the both sides of and clgse go the cut Then other hand a dull carborundum wheel should be used give a quick bending motion away from the cut Always break right after Cutting Bent Glass 39 Fig 318 cutting so the cut does not getquotcolclquot quotAll bent glass must be cut on the concave or inside surface of the glass Never remove more than a 2 inch strip at a time when cutting bent glass The break can also be made by plac ing a wooden rnotchsiick or similar object on the flat surface under the cut near one edge and pressing down on both Sides CAUSES AND CURES OF GLASS CUTTING PROBLEMS if any difficulty is experienced in making cuts opening or running cuts or cutting plastic in shatter proof glass the operator should go over the following very care fully T Poor Ragged and Chipped Cuts Skips or blank sections in the mark made by the cutting wheel a CausePoor or dull cutting wheel Wheels oc casionally become flat on part of the edge CureTry a new wheel b CauseUneven pressure on wheel in making cut CurewUse an even pressure practice on scrap glass Too much pressure on a new wheel may be bad C Ccuse Fro2en wh39eel wheel not revolving as r A4 4 p 3 quot 1391 39 3 P 2 cut is made Cure Free the wheel or try new stem and wheel Wheel usually can be freed with light oil To 99 349 lC Wt95i 39 Red 9 Vll 70 it avoid flaking coat the surface of the plate where the cut is to be made with the lubricant it is 7 TO break Off h 39 W SW95 U95 the suggested that cutting wheels be kept immersed Slots l lhe CUlf939 Hold the 9lU55 lit in a small shallow canlid partially filled with One hcmdr lhe Cutter 5 the Olheh A kerosene and tight oil mixture when not in use firm mowamehl GWUY h390m the Ctftwlll This is also convenient for dipping cutter prior Fig 319 separate the glass Tapping the under to making Cuts on gGs5 1 side of the glass right aftermaking d ca5eT0O mgch presSUf e39 the Wt WY make it 53PC 0f9 mme Cure Press iust enough to mark glass clearly 0 K easily le CauseGlass not lying entirely on tevel table 39 CureSee that there is no overhang Fig 320 aublex patterned glass Courtesy AmericanSaint Go bain Corp Note A firm even pressure will make the best cut A good cut is clean and even with a shine when wiped dry Flakes of glass rough lines chips wide marks and continued chipping indicate the need of further practice on the part at the operator or that the plate surface needs oil Never attempt to cut through drops of water 2 Cracking of Glass Away From the Line of Cut a Cause Poor cutting See above causes CureNew wheel More practice bl CausemFailure to hold glass cutter square with rule or pattern Cure lf cutter wheel drags sideways slightly the cutwill appear snowyquot somewhat the some as with the application of too muchpressure Be sure to hold the glass cutter so that theside is flat against the rule or pattern if the edge of the rule or pattern causes the cutter to drag apply oil or grease to the edge Never allow cutter to be out of line with the direction of the cut c Cause Cold air drafts on the glass CureBe sure you are cutting in a normally warm room 60 to 75 degrees F Glass must be at 75 degrees F or above when cutting A cold piece of glass brought into a warm room has internal strains in it because the outside surface is warm and the inside is colder Allow plate to warm up thoroughly before cutting d ause Fa lure to run the crack before the cut gets cold A cut will heat in one or two minutes appearing the some butlosing its ability to guide the crack CUTTING GLASS e 17 Fig 32 Randex patterned glass Courtesy AmericanSaint Go bain Corp Cure Do not allow much time to elapse before running the crack As each cut is made it should be opened e CauseToo much pressure in runntng crack Cure Apply gust enough pressure to crack clear across the plate by one operation Never apply pressure ahead of the crack f Cause Esp39ecially on LAMINATED GLASS Care lessness on the part of the cutter in failing to make the second cut directly over the first Cure Good tighting conditions careful cutting and experience The offset formed by uneven cuts subiects the glass to ansevere strain when the cracking operation takes place Note A new cutting wheel usuatly works best on sheet glass and a slightly used cutting wheel on plate glass it the wheel is too sharp causing excessive flak ing oil the glass and use wheel with no more than ordinary pressure Fig 322 Wire saw used for cutting thick glass Courtesy Tyso man Machine Co Section 4 512quot w niwu 34 sews vi Cutting laminated safety glass gtz gr p j aw lt33939quot39E g wzttiitt si a Laminated safety glass consists of two plates of glass or lights with interlayers of tough transparent plastics that are bonded tightly together with the aid of heat and pressure It is made in this fashion so that even though the laminated plate is broken practically no part of the glass will be exposed to inflict injury this type of glass is available in many thicknesses to satisfy the requirements of a multiplicity of uses One of its most common uses of laminated safety glass is in auto mobiles and so the following cutting instructions will be centered around this type of operation The same procedure as for plate glass and window glass is followed in cutting laminated safety glass with Laminated safety glass is frequently cut to add shapes such as the windows of cars To make sure the glass will be properly cut a full size pattern is first drawn on heavy paper The blocksize safety glass which refers to the size of the glass asitarrives in the shop is placed over the pattern and the design traced on the glass with the cutter ln shops where a great deal of car window repair work is done prepared professional pat terns are purchased for this use On some occasions the cracked or broken original glass is used as a pattern The original glass is placed on top of the blocksize safety glass and traced Should the novice have trouble with the glass pattern slipping while it is being traced the trouble can be eliminated by placing a few pieces of friction tape between the glass pattern and the blocksizy e glass Note Before starting note the type of edgework used on the original glass If ground or polished edges are to be furnished the cut should be made the exact size if not cut l32quot undersize several additional conditions to be met Preparing the Glass ln working with laminated safety glass make certain that the glass is kept in a warm room or put it in a warm place before cutting Glass is much easier to cut and less likely to break when warm than when cold if glass is taken from a cold room place it near a rod iator for 5 to i0 minutes before it is cut This will allow the glass to warm up all the way through and prevent internal strains which rnight cause breakage in cutting Fig 42 Pushing the cutter makes it easier to follow a guide tine Courtesy LibbyOwens Ford Glass Co Use of the Pattern Fig 41 Body light pattern on block size glass showing cutting rnarksCourtesy Pittsburgh Plate Glass WASTE BODY LIGHT Fig 43 Thumb pressure can be used to run the cut Courtesy IibbyOwensFord quotGlass Co This will make the glass easier to install and will not require forcing Place blocksize safety gloss over the pattern making sure that the block size allows enough margin for cutoff If the cut is less than one inch from edge use glass pliers to carefully run the cut The same results can be achieved by tapping Making the Cut Do not press hard on the cutter For best results exert just enough pressure to make a fine light cut Too much pressure causes flaking which may destroy the cut Then too these chips are often actually minor runs which may become cracks in the glass later on Pull or push the cutter in following a straight edge or a pattern thick enough to serve as a guide for the cut fer you will probably pull the cuttertoward you How ever where you must guide the cutter by watching a pattern placed under the glass you will probably find it easier to push the cutter Fig 412 This enables you to follow the pattern without having the cutter itself hid ing it This applies too in making the second cut on a piece of safety glass where the one must be directly over the cut on the opposite light Having one cut directly above the other avoids a lot of grinding later an and makes it much easier to cut the plastic Hints onCutting In cutting the combination safety glass one light sin gle strength and the other double strength it is best CUTTING LAMINATED SAFETY GLASS e l9 to cut the heavy glass first making certain that you run it clear through its thickness Then cut and run the thinner glass Do not try to hurry Remernberthe time you save by rushing a iob wilt be lost if you break the glass and you have lost the price of the block of glass Running the Cut Using thumb pressure on glass when it is standing on edge as demonstrated in the picture is practical Fig 43 However laying the glass flat and using the tapping method to run the cut proves more success ful Here is where the givequot of your felt table top comes in handy press on the glass with your thumb and you39ll find it bends enough to run the cut lndoing this how ever keep the pressurelbehind the run Avoid excess pressure as that often causes chipped edges or it may vent the glass it the cut is less than an inch from the edge use glass pliers to run it Good results are also obtained by the tapping method there is less chance of chipping Figure 44 Corners may be run by flexing or tapping Fig 45 Regardless of which method is used make certain that the run goes clear through each light of glass After making the cut on one side of the safety glass run that cut out before turning the glass over and making the second cut If this is not done a vent will invariably occur along the first cutf Fig 44 Best results are obtained by the tapping method Cour tesy LibbyOwensFord Glass Co PLASTIC STRETCH ED FOR CUTTING f D PULL i 4 IF WASTE emss IS FORCED DOW ClRPS WILL RESULT HERE Fig 48 Courtesy Pittsburgh Plate Glass plastic membrane is cut Use a sharp razor blade of the single edge type to cut the piastic Fig 47 Stretch the plastic only enough to allow for the free entrance of the razor blade Do not let the cut off glass sag as it may stretch the plas tic Fig 48 8 9 Note The razor blade should have its temper removed by heating This makes it more flexible so that it follows the contours of the cuts better and reduces blade breakage There are special laminated glass cutting and heating tables available Fig 4lG They are made with a reg ular cutting table top that is hinged so it can be lifted out of the way to expose an asbestos top table which includes a variable hot wire facility Figure 4l l shows a safety glass cutting board A specially designed tank used for softening the plastic in safety glass is pictured in figure z1l 2 Fig 49 Courtesy Pittsburgh Plate Glass TABLE TOP 2 3 J 4 39 CUT WITH RAZGR 9 Q9 BLADE wims Q smsrcasn 53 AT i E N GLASS 0 CUTTING LAMINATED SAFETY GLASS e 21 Fig IMO Laminated glass cutting and heating table Courtesy Sommer and Maca Glass Machinery Co Preparation of Glass for Grinding Be sure that all excess plastic is cutoff flush with the glass Otherwise the extended plastic will cause bump ing and possibly chipping of the glass while on the grinding wheel 39 Be a good housekeeperquot applies particularly to your glass grinding equipment Keep your wheels in first class condition properly dressed and clean Recom mendations on types of grinding wheels for various operations in your shop how to use thern and their care are given on pages 44 amp46 PROBLEMS lN CUTTING LAMINATED SAFETY GLASS CAUSES AND CURES 1 Difficulty in Stretching Plastic a CauseNot enough heat CureUse the hot wire for a longer time b Cause Failure to cut plastic quickly enough after heat application Cure Cut plastic as soon as possible it must be cut before the plate cools c Cause Cut not open at some point this is often the case when the waste strip is narrow CureRerun the cut 2 Bubbling In Center Of Plastic a CauseHeating too tong with hot wire The plas tic bubbles when burned Cure Shorten heating period or lengthen wire it too hot The wire when heated should be about a Cherry Red If glowing brightly increase its length Heating wire should always be on waste side of cut 3 Excess Separation Along Edge Of Cut a CausewBending the waste strip down too far thereby stretching the plastic until it becomes thin CurePull straight out with glass pliers it s g i Q quotquotii 39 cL3 D 20 e THE ENCYCLOPEDIA OF WORKING WITH GLASS Fig 45 Corners are run by ftexing and tapping Courtesy LibbyOwensFord Glass Co CUTTING CURVED WlNDSHiELDS The outboard light should always be cut first To cut the inboard light turn the curved windshield over with the outboard light facing the table Before cutting sup port both sides of the curved windshield to prevent sagging A windshield body opening improperly realigned af ter an accident necessitates special care in trimming glass for replacement After making the score or cat use glass nippers with several thicknesses of cloth between the jaws This will distribute the pressure to conform to the curvature of the glass and with a little practice you will find that a curved windshield is as easy to cut as flat safety glass Caution must be observed when cutting shaded wind shields so the proper shaded area will be retained Match the fadeout lines of the shaded portions and ran the cut around the periphery t39is suggested that you take an old curved windshield and practice a few cuts before attempting to cut a good windshield Fig 46 tocator LEAD ASBESTOS CUTTING THE PLASTIC After the safety glass is cut and flexed on both sides the waste glass is held to the remainder of the light by the flexible plastic only Extreme care should be taken to avoid chipping of the edges of the glass or overstretching the plastic If glass is cold below 75 it is advisable to heat the ptastic along the cut line Trying to cut the plastic while it is cold may cause chipping of the glass and subse quent breaks A heating coil or other device applied to the cut for a few moments witl soften the plastic sufficiently Care should be used however to prevent overheating as too much heatwill cause the plastic to bubble if a heat ing coil is used donot39 let the wire get hotter than cherry red in figure 46 are shown Electric Heating Coil Locators that can be made to hold the heating coil for softening the plastic The nichrome wire heating coil fits into the groove of the asbestos while the weight of the lead holds the coil in position to conform to the cut The hot wire should be placed on the waste side of the glass lto to 336 inches from the cut In place of the hot wire method the stretching and cutting of the plastic may be facilitated if the glass is immersed in water at a temperature of 160 Fto 170 F for a short period not to expeed 60 seconds lt is im portant that the whole sheet be immersed Then im mediately upon removing the glass from the bath the Fig 47 Cutting the piastic Courtesy LibbyOwensFord Glass Co I Fig 4H Courtesy Sommer and Maca Glass Machinery Co 4 Don39fs Do nof exert foo much pressure in cracking and strefch ng plastic Do not jar or bump a plafe while hot Do not make 0 fresh cut on a hot plate Do nofwef a hot plate Do not apply hot wire fo plaire colder fhan room femperafure Do not apply heat foo long Do not place hot wire on paffern side of cm Do not stop cuts before they have been run lo quot39139eltrs sv Fig 432 Tank for softening plastic in safety glass Courtesy Sommer and Maca Glass Machinery Co the edge of The light I Do not try to remove too much waste at one fime 1 Do not allow any overhang beyond the fable when making cut Cutting glass disks Glass disks of various sizes may be needed for such things as table tops picture frames replacement of glass for ctocks or fiashlights etc All that is needed to produce a disk of glass is to make a continuous clean tight cut on glass equal to the exact size of the circle desired It makes no apparent difference whether the glass is held stable and the cutter rotated on the glass or the cutter held stable and the glass rotated below the cutting wheel The former procedure is the one customarily used however the latter is superior for cuttingisrrzoii disks Fig 5l Circle cutter Courtesy FietcherTerry Co GLASS DISK CUTTERS in figure 5 is shown a glass disk cutter that iscus tomarily used for cutting circles It consists of a large suction cup in the center with a moveable rod sticking out above it On the rod is a device for adjusting the cutter to different radii The cutter illustrated will cut circles from 2 inches to 24 inches in diameter Larger ones are avaiiable The disk cutting machine shown in figure 52 cuts much faster and more accurately than the cutter mentioned above it is of course much more expensive than the above and is only recommended for use where quantity cutting of glass disks is a consideration The machine shown in figure 53 cuts ovals as well as circies CUTTING DISKS BY THE CUSTOMARY METHOD Note in these instructions the simple disk cutter as illustrated in figure 54 is used to score the desired circle in preparation for the cut Section 5 1 Pull out the rod ofithe cutter to the proper diame ier and lock it in this position with the thumb screw provided 392 Lubricate the cutter wheel with adrop oflight oil or light oil and kerosene mixture 3 Place the glass flat onwthe cutting table and press the suction cup down firmly on the spot that is to be the center of the disk 4 Press firmly on the suction cup with the left hand while rotating the cutting wheel with the right hand Fig 54 5 Scribe random radial fines from the circle out ward to the edge of the panel Fig 55 6 With the ball end of the cutter start tapping on the underneath side of the circle Watch for the crack to carry through belowlthe cut Continue to carry the crack all around the circle then do the same on the underneath side of each radial line 7 As the cracks are carried through each of the radial lines the waste glass will break away in segments Fig 56 Note Circles do not usually break as cleanly as do straight cuts Large chips that continue tohong on after the rest of the waste has been removed can be nibbled off with gazer39s pliers Small ir regularities can be polished awaySee polishing Fig 52 Circle cutting machine Courtesy Red Devil Tools 22 Aw camp 421 iIlt J39mL 24 9 THE ENCYCLOPEDIA OF WORKING WlTH GLASS r Fig 53 Ovai and circte cutting machine Courtesy Fletcher Terry Co IMPROVISED DISK CUTTERS When a commercial disk cutter as described above is not available a cutter may be improvised from parts found in most shops Following are a few suggested methods for scoring circles Once the circle is scored the operation would be continued by starting with step 5 on the above list under Cutting Disks by the Customary Methodquot Fig 54 Courtesy Red Devil Tools Method 1 Lock alregular glass cutter in the pencil leg of a carpenter39s trammel point set Place a suction cup in the center of the circle and place the center point of the trarnmel on the suction cup Holding the center point firmly on the suction cup swing the cutter slowly about the circle Method 2 Pivot one end of a strip of iron or hard board on a screwtitted suction cup these can be per chased in autosupply stores Clamp a regular cutter to the strip at a distance from the center of the suction cup equal quotto the required radius then score the circle as described above Method 3 in this method the cutter is held stable and the glass is rotated First devise a turntable For cutting small pieces at glass one may be made by drilling a hole in the center of apiece of metal or hardboard and loosely screwing it to a base piece at wood so the metal or hordboard can be rotated For large pieces of glass a turntable can be made by using the bearings that are used to make Lazy Susan table tops these bearings can be secured in a few different sizes from most large hardware stores The bottom plate of the bearings can be screwed or clamped to a bench top while a piece of wood connected to the top plate will rotate freely Stick the glass from which the disk is to be cut to the turntable by using melted beeswax or with masking tape pressed along the edges Locate a regelar glass cutter at the radius desired then clamp it securely to a fixer beam over the turntable Press clown firmly on the cutter as you rotate the glass on the turntable beneath it Method 4 When a machine lathe is available a disk Fig 55 E t 3 IN l4 39 Fig 56 Courtesy Red Devil Tools may be scored as follows Mount a piece of wood on a face plate and turn it up perfectly flat on the lathe Mount the glass to be cut to the wood on the face plate taping it securely with masking tape ontall edges Place the faceplate back on the lathe Mount the cutter in the tool rest and ran it up to the gloss until the cut ting wheel is pressing firmly against the glass at the radius desired The face plate can then be rotated by hand for one revolution or the lathe can be set to the slowest speed possible and turned on for one rotation Fig 57 Note Equally satisfactory methods for cutting disks can be devised from an old recorclplayer turntable or pottar39s wheel when available a cumno omss DISKS wire rm smws An easy way to cut a thin glass disk that does not re quire an accurate and clean edge is to cut the glass under water with a compound lever tin Snips having serrated cutting edges To do this it is important that both Snips and glass be submerged in the water First mark a circle on the glass with a grease pencil then nibble all the corners of the waste gradually forming a circle by taking bites not over l8quot wide When done carefully it is possible to get right down to the marked circle CUTTING GLASS DJSKS 43 3 0 2 T Isl Ni 0 Section 6 How to make unusual cuts in glass it is occasionally necessary to make cuts in glass that are other than straight lines and complete circles When such cutting problems occur they must be given special consideration and cut with extreme quotcare if an accurate glass segment is to result Before commencing to make an odd shape cutin glass the shape required should be carefully considered in relationlto the glass sheet for much glass may be saved by the economical use of materials if it is not easy to see how the shape can be cut from the sheet with economy the shape may be traced off on to scrap paper The template cut out in paper may be moved about on the glass until a suitable farmatien is discover ed which will cause a minimum of waste When the position is ascertained the glass sheet should be placed conveniently on the cutting bench with the template beneath The cutter should be slowly run around on top of the glass following the outline of the template Should the novice have difficulty fallowing the template in this freehand manner he may cut the template from thick cardboard or plywood place the template on top of the gtass and use it for guiding the cutter EXAMPLES OF UNUSUAL CUTS Fig 6 t Proper methods for cutting reentrance angles NOT GOOD NOT GOOD M M M me e a Fig 62 To cut internal squares score as shown Reentrance Angles in Figures 6 are sketches illus trating the proper methods for cutting reentrance angles in a glass sheet The sharp corners will vent orbreak the arrowed curves show the correct method for making this type of cut it must be remembered that when sep arating the cut segment from the sheet that the internal curved corner must be separated first Internal Squares A square opening may be cut in glass it the following directions are observed First cut the outlines of the opening desired but note in Figure 62 that the cuts are not completed to the corners Next tap the underside of the glass sheet with the ball end of the cutter handle at the center of each cut Continue to tap the glass at these points until a crack starts to develop Following this make diagonal cuts in two directions and equally spaced as indicated Tap these cuts from the underside to start cracks or fractures in both directions Then knock out the center square lfthe cuts are complete and the breaks well started ttquotwill drop out when tapped lightly with a mallet Then break or nibble away the triangular cornerssthat remain Arches Arches as shown in figure es may be cut as follows First cut the semicircular and straight cuts to one edge as shown Then crosshatch the waste with evenly spaced cuts Carefully start to tap the waste glass on the underside of the diagonal cots working from the edge in As the cracks start to develop along the cut lines it is possible to remove the waste one piece at a time until the top of the arch is reached Do not expect the cuts along curved lines to be as smooth as those which can be made on a straight cut The curved edge will usually need a little quotnibblingquot with glass pliers and polishing Odd Shapes it is impossible to anticipate all the differ ent kinds of cuts that will confront the student as he be comes more involved in glass work Following are a few illustrations that wilt suggest solutions to most of the problems that will arise To cut the piece of glass AB CD in figure 641 from an irregular glass sheet proceed as follows The shape would be laid out on the glass sheet as shown to take advantage of the straight edge of the sheet for side CD The first incision should bemade from F to Y This will complete the side A8 as required and at the some time separate the desired piece from the main sheet the two remaining pieces are removed by cutting along AC and 8D Cutting concave and convex curves present a particu lar problem because they are breaks that run contrary Fig 63 internal arches are scored for cutting w yes i lt kx s HOW TO MAKE UNUSUAL CUTS IN GLASS f9 27 Fig 64 to the normal breaking pattern of glasstocut outCurve X in figure 65 first make cut A8 then CD and finally EF The nearer to a complete circle the curve desired happens to be the more cuts will have to be carried to the outside edges as B and D When all cuts are com pleted stort tapping underneath the glass at the center of the curve and work in both directions Carry the cracks out to B and D by tapping underneath and the cut segments will break away a piece at a time leaving piece X Should a piece such as Y in Figure 66 be desired requiring the removal of an internal curve such as piece Fig 65 B 39 C W wz owvZww wnw 3 lt U0 4 6 c 0N0 4 0N0 eM gtzszy quotWv tv 39 me Wt r i 39 39 39 Z 28 THE ENCYCLOPEDIA OF WORKlNG WITH GLASS X it can be accomplished as follows First make cut AB as shown in figure 66 the full size of the piece to be removed Following this make a series of concentric incisions on the waste portion of the glass Each cut should be taken out to the edge of the glass at intervals of about an eighth of an inch for normal work though for large work more space may be allowed between the parallel incisions The main consideration is to wea ken the waste portion as much as possible When all the incisions have been made the cuts may be tapped be ginning at both edges of the glass and working towards the center Before all the cats have been tapped the waste glass should fall away but if it continues to hold after considerable tapping the unwanted portion may be nibbled away with the glazier39s pliers DEVCON EPOXY Available at Hobby Stores and Hardware Stores Advantages Fast 5 minutes Low Shrinkage Can be colored with Epoxy Colorants Can fill gaps Good for large surfaces and point to point Disadvantages Yellows Can break down with time Difficult clean up Application Mix equal amounts of hardener and epoxy Types 5 minute 30 minute SILICONE SEALANT Available at hardware stores Much cheaper if purchased in bulk from Sommer and Maca They have 5 toll free numbers depending on your location 1800 3239200 is the main number Advantages 39 Flexible Variety of Colors Relatively inexpensive in contractors tube Not Brittle Strong if used over large surface After setting can sometimes be separated with razor blade Bond does not deteriorate over time Disadvantages Clear is still cloudy Bond is flexible over point to point Difficult clean up need razor blade Application Squeeze from tube or applicator and use as is Surface skins over in short time Types GE Construction 1200 has tensile strength of 450 psi GE SCS 1000 has tensile strength of 320 psi 54 ARALDITE EPOXY AY103HY956 Available only from the following address Conservatdon Materials 340 Freeport Blvd Box 2884 Sparks Nevada 89431 Advantages Permanent Low Shrinkage excellent optical quality Can be colored Will ll gaps Good for large surface Will bond well on glossy glass surface Not effected by solvents Disadvantages Long setting time Expensive May slightly yellow Difficult clean up Application Two part system 17 Ilardener to 10 epoxy Mixes best when slightly heated Must be mixed accurately Acetone surface preparation ABLE BOND Available from Same as above Advantages Permanent Low Shrinkage Excellent optical quality Can be colored Will fill gaps Good for large surface Will bond Well on glossy glass surface Not effected by solvents Disadvantages Must be evacuated to remove bubbles Long setting a39rne Expensive May slightly yellow Difficult clean up Crystalizes in container Application Twopart system 32 hardener to 10 epoxy Mix and evacuate vacuum evacuation Acetone used for surface preparation 55 HXTAL Available from See Araldite Epoxy Advantages S Clearest of all epoxies Low Shrinkage Excellent optical quality Will fill gaps Good for large surface Will bond well on glossy glass surface Not effected by solvents Two hour pot life after mixing Disadvantages Needs heat for best set Must be evacuated to remove bubbles Long setting time Expensive Difficult clean up Can cause derrna tis Application Twopart system 1 hardener to 3 epoxy Acetone used for surface preparation lsopropyl alchohol for clean up Reagent grade alchohol may be used as thinner up to 10 GENERAL ELECTRIC RTV 615 A S 8 Available from See Yellow Pages for nearest distributor of GE RTV silicones look under Plas cs in business to businessyellow pages or call GEfor information on nearest distributor 1800 4335566 Advantages Easy clean up around edges Good for large areas Good op cal quality Disadvantages Setting time is very long Set quality is exible Expensive Not recommended as an adhesive but is used as a potting compound for electrical connection or electonics Application Two part system 10 to 1 ratio mix thoroughly Prepare surface with acetone Set time accelerated with heat 200 0 E for 6 hrs Primer needed 56 LOCTITE IMPRUV OPTICALLY CLEAR UV ADHESIVE 34931 Available from See Yellow Pages for nearest Loctite distributor or call Loctite directly for nearest distributor 18005620560 Advantages Disadvantages Application In Akron area Bearings Inc 621 Miami Akron OH tel 8674220 One part system Easy application Very Strong Instant set with UV light Optically clear Fills Gaps Easy clean up Glass must be clear One part system Do not apply in sunlight Clean surfaces with alcohol or acetone After application expose to direct sunlight or UV black light There are many different types of adhesives Listed are some of the adhesives that glass artists use When using adhesives it is important to know what the life expectancy is for that particular adhesive It39s rather embarrassing to sell a piece of glass that is quotgluedquot together and get a call in the middle of the night from some collector who is coming un glued because your 15000 piece of glass became unglued When gluing objects crafts manship and cleanliness counts Parts must fit well for the adhesive to work optimally 57 THE CORNING RUSEUM OF GLASS SIGNIFICANT DATES IN THE HISTORY OF GLASS early 2nd millennium BC 158013S8 BC p Bo C p Bo co 1412137SBC circa 1500 BC 12001000 BCl late 9th cen BC39 722705 BC circa 7th let cen BC circa 2nd 1st cen BC circa 2nd half lst cen BC 27 BC circa 1023 AD circa let cen AB zirca 50I00 AD eirca 4th can AD Use of glass for heads and inlays Development of core techniques 18th Dynasty of Egypt appearance of well made core vessels Rei n of Thutmose III in E t w 3 vessels with his cartouche have been found and are probably the earliest dated glass vessels known They are in The Metropolitan Museum of Art the British museum and the Munich Glyptotech Reign of Amenhoteg II in Egxpt piriform glass bottles found in his tomb b Rei of Amenhote III in E t fragment with an inscription referring to his wife in The Corning Museum of Glass 59140 Mosaic fragments found at Tell alRimah Iraq fromthis era Mosaic beakers found at site of Marlik Iran Beakerfound at site of Hasanlu Iran Rei of Set on II of the A35 rian ire Ira a vase with his name is in the British Museum and is the earliest39deted glass vessel of the first millennium BC Periodof massive cut glass pieces Hellenistic workshops in Alexandria gold glasses millefiori etc Invention of the blowpipe Proclamation of the Roman Emire Hold ptessed medallion of Drueus son of Emperor Tiberius Ennion and other workshops in Syria possibly in Sidon others who signed glasses Jason Nikios and Meges 39 Workshops of M Licinius Diceus and Frontinus in Gaul Christian gold glasses probably made in Rome circa 250350 AD 410 AD 476 AD 226633 AD 622 AD circa 800120O AD circa 12001400 1260 1399 1090 1224 1226 1291 9460L600 1406 1324 1486 1534 1541 135 Period of diatreta examples in British Museum Vienna Venice and K31n and fragments in other places Sack of Rome by Alaric the Goth Final fall of the Roman Empire in the west Sesanien gggire in Persia and Mesogotemie w heavy out glasses Hegira of Hohenned beginning of Islamic cons quests Greet period of Islamic cut glass Period of enameled glasses many bearing the 39 names of the Caliphe end Emire for whom they were made Sack of Aleppo by the Mongols consequent dew cline of glass enemeling there Seek of Damascus by Temerlene quotP Flebanicns Ficlariuequot bottle maker men tioned in e Venetian document First recorded Venetien gleseneker Guild of glaesmekers mentioned in Venice Laurence Vitreerine gleesneker at Chiddingfold in England mentioned in local records Decree prescribing that all Venetian glans furnaces be movedto Mnrano Gleeo being made by itinerant glneenekere in the forests of Centrel Europe Speseert Ordnung rules for gleeemekere in the Speeeert39 nerceloneg Spein Edict forbidding the construc tion of glass furnaces within the city walls Venetien type glasshouse established in Vienna Glesshonee founded at Hall in the AustrienTyrol to make Venetiantype g1eee Evidence of Venetian workmen in Antwerp Earliest dated piece of German enameled glass Hamburg N3 1567 Jean Carr came to England to start a window glass factory 1569 Venetian glessworkers mentioned in Liege town records circa 1570 Lt Glasshouse begun in Innsbruck Austria under patronage of the ducal court 1575 I l I G Verzelini39s patent to make glass in the Vene 39 tisn manner in London granted by Queen Eliza beth I 39 15831584 A N 39 quot pyenetian glasshouse in Hesse Cassell circa 1590 I 7 l I Casper Lehman Prague began engraving on glass using gemcutting technique 39 1610 i l I first patent issued in England for the use of i 39 ooe1 es fuel 1512 p p gt n P1ib1ication of L39AR39I39E vsmaam by Antonio Neri 1615 r Edict prohibiting the use of wood es fuel in 39 English furneces 17th cen 39 n H ej Glass engraqing workshops at Nuremberg flourish oiroe 16201700 Diamond point engrevers working in Holland an Anne Roemersmvisscher Willem van Heemskerk Willem Mooleyser and others so 3 circa 15651570 I Johann Schaper decorating glass in schsertzlotb melerei technique in Nuremberg 1574 quot 39 1 Publication in Potsdam of Kuncke139s ARS ITRARIA EXPERIMENTALIS 1676 h f George Ravenscroft and the Glass Sellers Company in London announced that the defects in glass of lead had been remedied 1676 39 J Knngsholn Glass Works founded in Sweden Second half 17th cenquot l Developmen of potashwchelk glass in Germany circa 1680circa 1770 Glass engraving workshops in Berlin circa 172O17amp8 Franz Greenwood stippler working in Holland mainly on English lead glasses circa 1729139 j Ignaz Preisler working in sohwartzlotmalerei 39 technique in Silesia and Bohemia 1736 1741 1745 1777 1780 circa 1784w1794 circa 179018amp0 circa 1819 1823 1825 circa 1830 l850 18amp539 19th cen 1851 circa 1870 circa 18701910 1917 Foundation of the royal factory of La Granja de San Ildefonso in Spain Beginning of the Norwegian glass industry factory at N atetangen Excise Act in England enacted taxing glasses by weight Second Engliah Excise Act heavier taxes on glass Ban on the export of glass from Ireland lifted hence several English glaaahouaea moved to Ire land which was exempt from the glass exciaea David Wolff atippler working in Holland Period of transparent enemeling on glass mostly inAuatriawJJ Mildner Samuel and Gottlob Hbhn Anton Eothgasser and others Ansley Pellatt Junior working at the Falcon Glaseworka London Factory of JampL Lobmeyrlatarted in Vienna 39Homgaerd factory atarted first in Denmark Factory of Egermann in Bohemia producing quotatonequot glasses Repeal of the excise taxes on glass in England Growth of the Stourbridge area as a glaaamaking center in England 39 heCr2 al3939a Pqle a g39Ia8a exhibited from all over the world Emile Galle began experimenting with glass deca oration beginning of the influence of 139art nouveau in glaaa Revival of the ancient technqiue of cameo cutting on glass in England by the Northwoods g ur bridge Simon Gate and Edvard Held went to work at Orrefors beginning of the modern movement in Swdiah glass The following list of vendors and products is from my experience Comments about products are included when possible Please write if you have any additional suppliers of speci c products or commentaries on a product and I will be glad to include it in the list Please supply an uptodate address and telephone number Prices for some products are included but they go out of date very quickly Henry Halem 429 Carthage Ave Kent OH 44240 Phone 216 673 8632 Fax 216 6772488 SAbrasives amp Diamond Products Salem Distributing Co Inc 2550 Viceroy Dr Winston Salem NC 27103 Phone 800 2341982 Diamond Saw Coolant Salem sells all types of abrasives including alumina oxide silicon carbide cerium and pumice We buy our abrasives from this company Send for free catalog Salem also sells diamond saw coolant If you use automatic diamond cut off saws and you use Salem39s synthetic coolant you may find your saw binds We switched to an oil based coolant and have never had a problem The oil based coolants are not made by Salem but by the major oil spill earth raping labor exploitive oil companies found in your yellow pages I recommend you use quotPella A oil or Mineral Seal 38 as a coolant instead of the standard synthetic coolants Pela A is made by Shell Oil and quotMineral Seal 38 by Chevron Most oil companies manufacture these coolant oils Danger Oil is a hydro carbon and is harmful if the fumes or mist are inhaled Using oil as a coolant in a diamond cut off saw creates a mist This mist is harmful if inhaled H Hinz Co 22255 Center Ridge Rd Suite 307 Rocky River OH 44142 Phone 3330477 Fax 2163337524 A great local resource for pumice They sell all grades 100 lbs of pumice is cheaper than the cost of shipping They have a 100 minimum order for each product offered They will ship less than 100 minimums if your order is accompanied by a check 1239 Abrasive Technology Inc 8400 Green Meadows Drive PO Box 6127 Westerville OH 43081 Phone 614 54841 00 1800 5488324 for orders Abrasive Technology sells some very ne if not state of the art diamond hand pads files and many other con gurations for diamonds almost too numerous to mention They also carry diamond belts for your large Sornaca wet belt sander I have been using a 7080 grit diamond belt on my wet belt sander for at least 3 years While I do not use it every day it has given me incredible service It literally eats through the glass The kick is that dia monds do not get dull like grit so the belts quottake a licking and keep on tickingquot Very ex pensive if you are used to buying silicon carbide belts But if you do a lot of wet belt grind ing you need at least one of these puppies The saving in me is where it39s at Send for their catalog with price list The catalog is a lot of loose sheets The price list shows all the prod ucts they carry They need someone to organize their catalog Fancy design but poorly informative Highly recommended company This company recently purchased the Crystalite Corporation listed below All the products that they carried are now distributed by Abrasive Technology Inc Crystalite Corp 13449 Be Whenever I read their addres H1 e eir lunch hour When their not sur ng they make some ne S polishing etc the crystal P 2 ts on your Merker lathe if yo handy Merker adapter Send for the Crystalite catalog and sur ng news SW Enterprises 13000 San Fernando Rd Unit 15 Sylmar CA 91342 tel 800 8252792 tel 818 3624526 fax 818 3627528 This company also makes a floor grinder and a table model grinder suictly hobby This company sells magnetic backed and adhesive backed diamond polishing pads that fit the rociprolap Very resonably priced I am told they Wear out very quickly You get what u you pay for Send for catalog 12339 Glastar 20721 Marilla St Chatsworth CA 91311 tel 800 4235635 tel 818 3410301 fax 818 9982078 This company sells mainly grinding equipment and diamond stuff Their grinding equipment has no heft and I assume their market is the hobbyist They do sell high quality polishing pads for the rociprolap These pads wear very well Call them for a catalog and see if they ll give you a discount on diamond products 9 Adhesives Loctite UV Adhesive Call 1800 5620560 for the nearest Loctite distributor Loctite UV Adhesive 349931 is a super strong optically clear adhesive used by many glass folk for general purpose adhesion of clear glass Many cities have a franchise com pany called Bearings Inc to distribute Loctite products Silicone Adhesive Dow Corning 732 RTV There are general silicones available at most any hardware store You may purchase general usage silicone in bulk much cheaper from SOMACA see SOMACA for address There is a much denser stronger and harder silicone actually RTV available It39s called Dow Coming 7322 RTV and is available from Bearings Inc in your area You will also need the Dow Corning Silicone Primer quot391200quotquot to go with it This is really superior silicone Call your regional Bearings distributor they usually carry exotic adhesives Call Dow Corning directly to find out who distributes this particular type of Silicone RTV Paul Marioni uses it exclusively for his installations that require Silicone Call him for up to the minute late breaking info on silicone Tell him quotHenry sent mequot Conservation Materials 340 Freeport Blvd PO Box 2884 Sparks NV 89431 tel 702 3310582 fax 7023310588 Amldite Epoxy AYLIO3HY956 Able Bond HXTAL These are the optical adhesives used by the anal retentive set Call anyone of them to get more information You know who they are I don t want to name names and get in 124 trouble Some of them are nice guys and my friends I think Well here s one name you could call for further information Bill Carlson Here is a small quote from the company about IIXTAL HXTAL is not your standard hardware store type epoxy adhesive It is a hightech adhesive that must be treated with care The two parts of IIXTAL must be weighed accurately and it cures slowly Cure time is about one week at 75 T and 23 days at 95 F We know of one glass artist who does all of his HXTAL cementing in a plasnc tent heated to 120 F to speed up curing Few glass artists resort to such extremes and the slow cure does offer some advantages A free jar of HXT AL to the first person to come up with the name of that artist I think I know who it is but I39m not telling The company also has a huge catalog of assorted stuff Fantastic bathroom reader 9 Blanket Insulation Standard Oil Engineered Materials Co Fibers Division P O Box 808 Niagara Fall NY 14302 Phone 716 2786221 Pz be7fmx Call the above number to nd the nearest Fibrefrax distributor near you Ohio Industrial Sales 2422 Edison Blvd Twinsburg OH 44087 1 4259163 This is a great regional source for all things Fiberfrax 6 Burners Dudley Gibberson joppa Glassworks Box 202 Warner NH 03278 603 4563569 Gib makes the best general purpose burner tip for the money that I have ever come across There are more of his tips heating up glass furnaces and glory holes than all the rest combined I think The price is right and so are the BTU s The 650 Burner Tip is the big gone and sells for 85 There is a smaller size but I don t know the number or the price Send for his catalog and homespun glass info He also sells other stuff for the glass artist 125 North American Burner Co 4455 E 71 St Cleveland OH 44105 Eclipse Combustion Division Rockford IL 61103 Phone 8158773031 Maxon Corp PO Box 2068 Muncie IN 47302 Phone 3172843304 These three burner companies make commercial burners and blowers as well as all the stuff that goes with them I couldn t begin to describe all the stuff they carry The Maxon Corp makes a fantastic premix not cheap but worth the cost Ask for Bulletin 2300 M The Maxon premix is used by39inany studios to run furnaces as well as glory holes Look in the yellow pages or better yet the Thomas Register for the addresses and telephones of your regional burner company If you haven t discovered the Thomas Register go immediately to your local library and ask for the Thomas Register The register is an encyclopedia of companies that manufacture products The listing is by state if you wish 39 Paul V Wilton Wilton Technologies 2932 Via Lorna Vista Escondido CA 92029 tel 619 745 5956 fax 6197451944 This company produces 3 sizes of Flame Retaining Ceramic Burner Nozzles The burner is cast from a heavy duty castable and Mr Wilton claims they will outlast any cast burner on the market today Unlike the steel ame retention burners this little beauty can be fully sealed into the crown of the furnace I would assume its quiet because of this feature I inspected these tips and they seemed to be very well constructed The informa tion I received from this company indicates that the largest size made will only run a 250 furnace Although other information provided indicates that his largest burner at 9 inches of WC will produce 800000 btu hr That will certainly run a furnace much larger than 250 lbs 9 Computer Controllers Advanced Technical Services Inc 21045 Des Moines Mem Dr o Des Moines WA 98198 206 8788046 ATS sells a device called Kilnwizard temperature controller It is comprised of the Partlow MIC 6000 with one output for one oven It comes with a Mercury Displacement 12639 Relay 220 VAC 35 amps 60 amp relay is optional type K thermocouple and power leads The controller has 6 ramps and soaks All you need is to hook up your power and run your leads to the Kilnwizard and you are ready to go The basic price for the unit is 840 If you only want the computer the cost is 510 Big drawback to the Partlow is that it has a very steep learning curve I found it practically impossible to learn Paragon Industries PO Box 850808 Mesquite TX 751850808 Phone 18008764328 Paragon Industries like Advanced Technical sells a complete computer unit You just plug or wire your oven to the UDC 2000 It uses a Honeywell computer also designated UDC 2000 It comes complete with either a 220 volt 30 or 60 amp mercury displacement relay Paragon will tailor the unit for any amperage you wish Before using the unit you must set the parameters of the computer for your par cular application Directions come with the booklet and I39m told the directions are fairly straight forward If you have any problems you can call Honeywell at an 800 number It runs one oven and has 6 ramps and 6 soaks Two year warranty Sells for about 900 The Honeywell unit alone is about 500 600 It is much cheaper to do your own wiring but not as convenient The learning curve for this unit is much easier than the Partlow Trust me West Instruments 3860 North River Rd Schiller Park IL 60176 Phone 312 6786400 39 This company sells a set point programmer controller The West Model 2050 has 4 ramps and 4 soaks Their model 2052 has 8 ramps and 8 soaks These units are not like the Paragon or Advanced systems which contain the relays and assorted wiring They are just the computer unit and you must wire the relays I use the 2050 It s OIlt but if I had it to do over again I d buy a Digitry Digitry Company Inc 108 High St Portland ME 04101 Phone 207 7740300 Fax 617 4845220 I still think the GB 4 is the best bang for the buck Five ovens at your fingertips Many options are available There is now a GB1 for only 1 oven I39ve seen this little beauty and it s really state of the art Almost everyone I know has a Digitry There are other computers available from mainline companies that work just fine but can be a bitch to calibrate operat ing pararneters Once you install the Digitry you set it and forget it There is also a replace ment program if your unit dies Call for particulars If a computer is the key to your busi ness you should own a backup Great phone help Please note There are new controllers coming on the market all the time so this list will not be up to date no matter how much I stay on top of it Find a controller distributor 127 0 in your area There are other companies that make controllers that are not listed above such as Honeywell Partlow and others 6 Furnaces Correll Glass Studio RR1 Box 150 Mathews Rd Conway MA 01341 tel 413 3694283 fax 413 3694769 Charlie makes a very fine pot furnace coupled with a state of the art burner and ame safety system His furnace also comes with a 200k BTU recuperator Having Charlie build you a furnace saves a lot of time effort and energy If making art is What you came to the swamp for then buy this beauty Call Charlie and ask him for his handy packet of informa o39on It is my understanding that these fumaces require close maintenance They work well in a private studio but can be a maintenance headache in a school situa on s Thermocouples Capp Inc 1700 E 13th St Cleveland OH 44114 216 6871242 This is a local distributor I think there are regional distributors Look in your nearest city yellow page Use the Business to Business yellow pages Thermocouple 2KriM22G12 16 or 18 gage thermocouple w quick connect cost 55 a few years ago 45 per ft for thermocouple wire 5W2P16 for quick connect This is the price of the thermocouple and corresponding wire sizes 14 gauge wire 5770 16 gauge wire 4750 these all include quick connect 18 gauge wire 4750 20 gauge 450 per ft 50 ft of type K wire 14 gauge 859 per ft 950 for plug connect wire I use this thermocouple and it works ne There aremany other companies that supply quotthermocouples at comparable and or cheaper prices Don39t skimp on the price for a ther rnocouple Correct temperature is your best friend 128 Refractories Crucibles and Related Products Ipsen Crucibles P O Box 420 Pecatonica IL 610630420 tel 8152392385 fax 815 2392387 Karen Nolan Senior sales rep Crucibles Er Mullite Tubes Ipsen Crucibles are excellent for direct glass contact especially the ICOR alumina round bottom crucible for direct glass contact These crucibles are round bottomed quot39to reduce thermal stress during charging or due to uneven hea ng They are numbered as follows 2532 25 lb capacity 98 2529 60 lb quot 140 2530 140 lb quot 216 2527 300 lb quot 72398 Ipsen will make custom designs for 500 Iv nimum order for stock items is 100 Send for catalog Prices are subject to change Mul900 Mullite Tubes manufactured by Ipsen Ceramics are inserted down the center of electric coils and can be either hung onto the crowns or walls of annealers The 3 8 od tubes tend to warp over time Irecommend using 1 2 inch or up These tubes are made to withstand the thermal shock I have used them at school and in my armealer at home for years Mullite Tubes Mul900 36quot 38 od 1130 1116 od 1085 3 4 od 1290 Call Ipsen for the distributor near you Make sure you use the MUL900 Cleveland Electric Labs 1776 Enterprise Plzy Twinsburg OH 44087 216 4862820 This address is for local Ohio distributor of Ipsen Mullite Tubes as well as thermo 0 couples 129 Laclede Christie John Bartel Cercon Ceramic Consultants Inc PO Box 116 Ilerrnann MO 65041 3144862410 or 3422 John is the rep for Laclede Christie round bottom crucibles These are very good pots and the price is competitive Send for catalog The Babcock 839 Wilcox Company Cerox Crucibles A very good crucible Address see The Thomas Register for address Didier Group Didier Taylor North American Refractories Cincinnati OH call for information Didier makes a good selection of crucibles Call to find which crucible is best for direct glass contact North American Refractories is located in many cities and is a refractories company that is part of the Didier Group North American Refractories carries many different corn panies refractory products This company is usually knowledgeable about the application of different types of refractories block castables ramables etc 6 Glass Furnace Block r Didier Taylor also makes a glass tank block called Vision Block Carried by North American Refractories This is a sintered AZS block but it is different from the Carborundurn AZS CS3 block The 39Vision block is crushed AZS then repressed into a block The supposed advantage to this block is it is less prone to thermal shock I don know anyone who has used it but the company recommends it for a soda lime melter Zedrnark Refractories PO Box 446 Dover OH 44622 2163438821 This company makes the same block as the Vision Block but calls it Zedmark bonded AZS HarbisonWalker Dresser Industries Inc 2 Gateway Center Pittsburgh PA 15222 412 3430050 Korundal XD Glass Tank Liner LIPALA XCR Above Glass Line 130 The Korundal XD liner is a very reasonably priced block and makes a fairly substantial day tank type furnace The Korundal X1 is as close to the old Al Green Crystalite as I ve seen We are using a furnace constructed from this block and although we are getting some wear the tank should last for three years For what you pay three years is just fine Make sure you get machine pressed standard shapes Tank wear is also dependent on whether your melting batch or cullet Cullet is less corrosive than batch Make the tank fit the glass I don39t know what this liner will do with a standard sodalime batch Those using Spruce Pine batch should be aware that it is somewhat corrosive as it contains some lithia The Korundal was recommended by Fritz Dreisbach Thanks Fritz Standard Oil Engineered Materials Co Refractories Division Monofrax Plant 501 New York Ave Falconer NY 14733 tel 716 4837227 fax716 6652478 Monofrax CS 3 Glass tank block This is the company that was originally called The Carborundum Co Standard Oil bought it It still makes some fine products The one we are concerned with here is glass block called Monofrax CS 3 It makes many Monofrax blocks but the CS3 is the one for sodalime glass This block is solid AZS AluminaZirconiaSilicate It is considered the ultimate in glass block Very expensive I don t know if it39s Worth the extra cost for building day tanks AZS is yeg prone to thermal shock and I mean The hotter you keep these puppies the happier they are but the higher your fuel bill is I39ve used them for some years and personally don t think their worth it in a school situation If you get them free that s another story They have mucho stock sizes but will cut any size to fit your needs Very nice people to deal with If your looking for a field trip this is the factory to go to To watch this stuff made is something else If you ve never seen 32OD F this is the trip for you Don t wear your Birkenstocks Monofrax is so dense that when you pick one up you think it39s a black hole This company also makes a leveling cement to lay the block in when you build the furnace It s called quotS cement AP Green Look in your yellow pages or Thomas Register for the nearest disuibutor 6 Solid State Relays Continental Indusuies Mesa Arizona Phone 602 9857800 Solid state relays for annealing ovens We use these relays on two of our small ovens and they work real good The relay itself generates some heat and has to be used on a heat sync Your relay of choice should be a mercury displacement relay No noise and very reliable Mercury displacement relays can be purchased from your local electronic supplier or from Newark Electronic Supply and WW Grainger Use a high quality relay Your 131 computer is only as good as its weakest link Part s5o5 os44o00o 332 DC Input40 AMP AC Continental also has relays with higher AC amp input Companies that carry this part in Ohio are Gateway Megatek 4740 Beidler Rd Willoughby OH 44094 Phone 9530333 Wedameyer Electronics 6740D Huntley Rd Columbus OH 43229 Phone 614 4369600 5 Grinders Lathes Polishers and Blow Pipes Sornmer S Maca Ind Inc 5501 West Ogden Ave Chicago IL 60650 tel 1 800323 9200 machinery sales 312 2422871 This company is regional Central Division Concord Division east coast Dixie Divi sion Texas Division Western Division Call the 800 number above for the division number nearest you Sornmer amp Maca distribute just about everything for working with glass including the manufacturing of heavy glass machinery It carries abrasives adhesives glass cutters breaking pliers plate glass suction cups stained glass supplies felt wheels cork wheels grinding wheels etc They also manufacture belt sanders platen grinders glass polishers glass drilling machines and all kinds of other stuff for glass that you39ll never need Need less to say it has a big catalog but it is tough to get one if you are not a company I think you can buy one It39s worth it Every glass shop in the country has something from SOMACA GranQuartz Gran Quartz Trading Inc 1804 C Montreal CT Tucker GA 30084 tel 404 621 9777 fax 404 6219771 132 This company sells hand operated power tools both air driven and electrical for polishing and grinding stone The tools are all adaptable for glass The one tool we have used and seems to be quite good for grinding and polishing is the Tornado 1 Pneumatic Angle Grinder it has a central waterfeed system sells for 365 The Tornado 2 Pneumatic Grinder costs 17400 It also has a central waterfeed but has a lower RPM as well a lower CFM It also sells all the diamond discs to go with the tools Send for a chock full of info catalog Steinert Industries Inc John Steinert 1000 Mogadore Rd Kent OH 44240 tel 216 6780028 fax 216 6788238 Some of the best blow pipes in the indusny among other things John will build just about any glass related piece of equipment if you send him a drawing His grinders are heavy duty and big He now manufactures a state of the art diamond grinder Almost everyone uses his pipes Also manufactures optic molds grinders polishers diamond shears yolks Send for free catalog John pracdcally has his whole family working for him there s Joe over there running the mill and Mary Jo behind the PC oh there39s Laura on the phone collecting money don fool with Laura John tried to get his Mom in there but she39s happy working at the university book store Send for Steinert s catalog Did you get a look at that jewelry line Pumch PO Box 5128 Asheville NC 28813 704 6840671 Manufactures jacks tongs tweezers blow pipes shears ball gathering irons yolks blow pipes Standard catalog shears and jacks not so hot but other tools like tweezers are OK They now sell the Italian Meniconi shears These are very high quality shears unlike the German ones Send for a catalog ARTCO 348 N 15th St San Jose CA 95112 tel 408 2887978 Good blow pipes and related tools ARTCO is the American distributor for Essemce Swedish hand tools Essernce makes good tools Also sells CRATEX productsThe company sells lots of glass related products Nice folk give em a call Send for catalog of products Jim Moore PO Box 309336 Seattle WA 98103 133 Phone 206 5226046 Iim makes fine hand tools Many of them are patterned after the Italian tools The jacks look exactly like the Dino s but don39t quite have the feel but close enough No need to pay the extra lira for feel But then again all the hip glass blowers have Dino s I ll bet your work looks exactly the same regardless of whose jacks you use My students use im s tools and they hold up under hard studio conditions Highly recommended Send for his catalog and price list Keith Orr Blowpipes Skeels Glass 101 S Coombs D4 Napa CA 94559 tel fax 707 2532287 Very nice blowpipes Lower prices than most and good quality Recommended for the student Send for catalog Officina Fabbrile Tedeschi Antonio Dino Via Convento 19 30121 Murano Venezia Italy That39s the address but I don39t think you can go direct You can purchase these jacks through Pilchuck Mucho bucks I just put in the address for show Dave Jacobs Paoli Clay Co 6879 Paoli Rd Belleville WI 53508 608 8457000 Dave sells blow pipes at head grinders and some other glass related stuff He also sells a lot of stuff for the pottery business in case you haven t guessed from the name of the company He bought the business from Harvey about 100 years ago and he39s one of the best people around His cheese at the GAS meetings is legendary If you buy him a beer he39ll tell you some great glass stories Rose Enterprises 3217 Annapolis Dr Bakers eld CA 93305 805 8720721 Rociprolap polishing machine This is the guy that makes the Rociprolap You can also purchase this p machine from Bill Carlson or Steve Weinberg They have a dealership and you won t pay more by 134 79 buying it from them Denver Glass Machinery 1804 South Pearl St Denver CO 80210 303 7448004 Denver makes a whole bunch of other glass machines We have a Denver band saw at school and I have one at home and it seems to hold up pretty well Kurt Merker Kelheim D8420 Kelheim Germany tel 94 41 33 55 fax 94 41 128 15 Werkzeug zum Glas Gernot Merker is the man in charge and if you don t think so he has ways to convince you That used to be true he now has a lovely daughter running things Her name is Isabell Merker This is the company that makes the famous Merker lathe This lathe comes in two sizes Small for fine engraving and large for not so fine engraving This machine is the state of the art and is unchanged for at least 100 years You will nd it all over the world It is one beefy machine Can cost some money after you finish ordering the motor and all the spindles Get the catalog for all ordering instructions Merker sells all kinds of glass equipment from state of the art diamond wheels to factory blow boys You MUST send for the catalog to get an idea of the vast array of stuff available This is not for the hobbyist Call Gernot or his daughter for fun They speak your language and like to talk about their machines These machines are 5 star I39ve never seen a used one for sale Gernot is also is a collector of glass posters 39Gloves and Safety Safepro Inc 3865 West 150th St Cleveland OH 216 9419400 in state 800 3232442 outside Ohio 216 9411130 fax Makes and supplies all kinds of heavy duty Kevlar mitts Send for catalog The owner of the company is a nice guy and collects glass We use Safepro as our glove supplier Tempo Glove Mfg Inc 3820 W Wisconsin Ave Milwaukee WI 53208 1800 5588520 FAX 4143444084 Industrial thermal protective products The gloves have a wool lining and come in 135 different lengths They also sell a neat slipover face shield This little beauty is great if you are leaning over a hot annealer and hate the smell of hair burning Heat sleeves also Send for catalog for all the products Gloves S81 14quot 3150 18quot 4000 23quot 5050 Over Mitten S512 14quot 3450 Head 8 Face Shield Tempo UNO 2800 8 Plastics United States Plastic Corp 1390 Neubrecht Rd Lima OH 45801 in Ohio 1800 8210349 outside Ohio 1800 5379724 FAX 4192285034 Rociprolap plastic balls All things plastic When I say all things plastic I mean it Plating tanks tubing rod valves etc Price and ordering number for the ball is Stock 91507 Nylon Balls 30 per 100 such a deal Also sells safety masks as Well as all types of safety equipment 9 Hand Torches llr Muus DeLange RR1 Site 135 C9 Port Alberni BC V9Y7L5 Canada Phone 604 7232515 EXACT Torches for Propane State of the art but see below The following torch is the model used by many glass artists There are other models and sizes but you should write to Muus at the above address for information I have seen this torch in action and there is nothing like it It has been nicknamed Glory Hole in a Can It is one hot little mother Handle 2401 Torch Handle w Economizer Valve 8370 Extension Tube 3710 4 inch Elbow Type 2650 Burner Tip 31455 Steel Burner Tip 125000 BTU 3 4384 Add 6 tax 1200 shipping 39 All prices quoted are in Canadian money Muus does not wish to deal in American bucks Says it takes too long to clear So get a Canadian money order He means it I couldn t do it his way and he really got pissed 136 Hand Torches different design than Exact torch but almost as good Roo ng Supply Co anytown USA Roo ng suppliers sell heavy duty hand torches in all BTU sizes Anyway we saw one in action and they are every bit as good as the Exact torch that Muus sells Please note you may have to cut the tip extension down and rethread it in order to make it into a usable size It39s well worth the effort as these torches are lower in price but just as good Tools and just AbouLEverything for the Shop WW Grainger Every City USA For your local Grainger dealer look in the yellow pages or call 18003230620 Grainger has warehouses in just about every city If you are not familiar with what Grainger carries you must have just arrived from Mars For the uninitiated it has name brand and Dayton brand motors blowers safety equipment power tools of ce equip ment hand tools bearings etc etc etc If you wish to buy you should have a business card as it may be needed for purchase The catalog is a must Great bathroom reading 9Wood Blocks and Wood Blow Molds Cherrywood Mold Shop Walter Evans Rt 1 Box 377 Kenova WV 25530 Phone 304 4532279 Walter is a good ole boy and makes some fine blocks and paddles His blocks are very inexpensive He sells German and Belgian style German style preferred by 3 out of 4 glass blowers Round or Oval blocks He will also make Cherrywood blow molds for you Iust like the kind used at Blenko Send hirn a drawing and he ll quote you a price Also paddles sticks WVa foot setter anything in cherry Send or call for up to date prices Prices for round blocks are 200 set up charge 230 per inch example 3quot block 890 Olympic Color Rods 2020 124 Ave NE Suite C106 Bellevue WA 98005 tel 800 4457742 137 fax 206 8854182 This company also sells Wood tools as well as color rods Electric Annealer Elements Duralite Inc School St Riverton CN 06065 203 3798113 This company makes the state of the art elements to your specifications Kanthal Kanthal A or Nichrome You need to know volts amps size of pig tail maximum tempera ture length of stretch gage and id The best thing to know when building an oven is how many watts you will need Watts is the key for electric ovens See my Building and An nealer chapter a Glass Enamels and Related Products Standard Ceramic Supply Co PO Box 4435 Pittsburgh PA 15205 4112923 1655 L Reusche Co 2 Lister Ave Newark NJ 07105 201 58912040 These two companies sell glass enamels The Reusche enamels are a great deal more expensive than the Standard The painters in the Seattle area swear by Reusche I never found the Reusche enamels melted at a low enough temperature for blown ware enamel ing If you have never done any glass enameling start with the Standard enamel you39ll save lots of money Both company s also sell lots of other stuff for enameling and lustering Send for their catalogs Degussa Corporation 104 New Era Drive South Plainfield N 07080 201 7576500 This is a German Co and it makes the best glass enamel in the world I purchased some in the Czech Republic The colors are very opaque and they melt at a very low tem perature I have never seen them for sale in the US in lots small enough to buy lam told you can purchase them in Germany in small quantities You may be able to buy these enamels soon as I39m told Degussa bought out Drakenfeld Joel Meyers says there s a place 138 in Texas that sells Degussa in small quanti es Call him Johnson Matthey Blythe 1397 King Rd West Chester PA 19380 215 6488100 Fax 215 6488055 Excellent glass enamels but like Degussa will not supply small amounts Drakenfeld PO Box 519 Washington PA 15301 412 2235900 Versicolor glass enamels Same problem as above This is the company that makes the enamel that David Hopper sells Paradise Enamels 9 Decal Paper Brittains Tullis Russell Inc 500 Summer St Stamford CT 06901 Phone 203 3247536 Fax 203 3241902 If you make glass or ceramic decals you should be using Waterslide decal paper If 39 you call this company they may send you a sarnple package I ve made decals and it39s a very smelly business but not that difficult if you have had some silkscreening experience s Rubber Products There are many company39s that sell castable and related rubber products I have listed only three If you buy a sculpture magazine usually found at a good magazine store you will find many companies listed that sell rubber related products The three listed below are company39s that I am familiar with and they have competitive pricing Smooth On Inc 1000 Valley Rd Gillette N 079339989 tel 908 6475800 Fax 908 6042224 SmoothOn rubber products are excellent lt has a whole range of rubber products and the price is right I use PMC 724 two part castable Urethane Elastomer The products are quite easy to use The only drawback for PMC724 is that the mixing ratio is done by 139 weight and not by volume You will need an accurate scale If you are doing Patedeverre editions 1 recommend you use rubber models The nice thing about PMC 724 is that you can obtain a part C or D to make the rubber more exible or thicker for putnng on with a spatula A two part rubber called PMC 121 does not require a scale to Weigh the parts lust mix equal quantities by volume great phone help Send for acatalog of products Wear rubber gloves Adhesive Products Corp 1660 Boone Ave Bronx NY 10460 212 5424600 Adrub RTVTM molding rubber is a two component liquid system which when blended together produces a room temperature vulcanizing rubber with superior tear resistance and solvent resistance I have used this stuff and found it to be quite good Easy to mix as the ratio of parts is 21 by volume Slightly more expensive than the Smooth On Call this company and get a catalog with many other moldable rubber products Talking to them on the phone is a trip Being from the Bronx myself I can relate Cernentex Latex Corp 480 Canal Street New York NY toll free 18007829056 phone 2122265832 Fax 2123348349 This company sells many different types of castable and brushable rubber products It has an excellent catalog that not only lists the products but also describes and shows with pictures how the product is used The catalog depicts and describes everything you39ve ever wanted to know about using rubber as well as how to make the molds in which the rubber is poured The catalog is literally a text book in itself Highly recommended a Cullet and Batch Frank Lane Gabbert Cullet Co PO Box 63 Williamstown WV 261870063 Phone 304 3756435 This company has been the main source of cullet for the studio and university for more years than I can remember Frank Lane a good ole boy took it over from the late and great Iiggs O Gabbert who was the goodest of the good ole boys as a matter of fact every good ole boy who was born after Iiggs was made from his mold If you can hear me Iiggs thanks for selling to Frank he39s doing a great job The base price for crystal is 18 20 a lb This company also sells colored cullet not necessarily compatible but some nice colors Cullet availability is always changing so you must call for what39s available 140 Spruce Pine Batch Co P O Box 159 Burnsville Hwy Spruce Pine NC 28777 Phone 704 7659876 This is Harvey39s Co and they sell pelletized batch The batch they sell was originally developed for Harvey by Nick Labino Those that use it tell me it s excellent stuff Higher price than cullet of course but think of the exibility you have in being able to make com patible colors 9 Color Rods or if you are English Colour Rods CampR Loo Inc 1085 Essex Ave Richmond CA 94801 tel CA 800 7723388 USA 8002271780 Fax 415 2327810 This Co has a great selection of color rods Kiigler Wiesenthalhiitte Zimmerman Discounts for quan ty Great telephone Send for catalog and say quothiquot to Theresa for me Littleton Co Inc P O Box 159 Burnsville Hwy Spruce Pine NC 28777 Phone 704 7659876 A great selection of color rods Discounts for quantity Send for catalog Olympic Color Rods 2020 124th Ave NE Suite C106 Bellevue WA 98005 Phone 800 4457742 Large selection of color rods Kiigler Zimmerman and Reichenbach as well as Block head wood tools for the serious glass artist I saw the wood tools and they looked fine Send for catalog and price list for uptodate information 9Casting Glass and Fusing Glass Bullseye Glass Co 3722 SE 21st Ave Portland OR 97202 141 tel 503 2328887 fax 5032389963 Bullseye has been making sheet glass for the at world for many years Bullseye39s Fusing Compatible Art Glass has been used by users for many years and is considered the standard for those folks Bullseye also manufactures a complete line of stained glass sheet The sheetglass catalog must be seen to be believed And I remember when Dan and I were giving Harvey a hard time back in Madison Bullseye manufactures a very fine casting glass and cheaper than Schott I have used this glass for some time now and find it does everything you could wish for in a casting glass It does not devitrify and softens at the correct temperature 1450 1500 F can be used in billet form as well as fritted It comes in both forms Bullseye also sells compatible colors for casting which is not a lead glass It is a very hard glass that is one has to work to polish it Send for the catalog or better yet call Dan to discuss your casting needs Dan gives great phone especially on your nickel 5 Assorted Stuff Anchor Tool and Supply Co Box 265 Chatharn N 07928 201 8878888 Assorted hand tools diamond tools for hand grinders and Foredom flex shaft insu lated gloves and stuff Comes to all the GAS meetings Nice guy Sells mostly tools to the jewelers Carries a moderate assortment of stuff for glass people His diamond bits are good Ed Hoy s 1620 Frontenac Naperville IL 60563 1800 3235668 Luminar and assorted stuff Wholesale only Ed Hoy is a Wholesaler of mucho stuff for glass folks He carries color bars flat glass casting glass etc etc You need the catalog to see all the stuff he has He also carries Luminar He will not sell retail Order through school or if you are incorporated He s always at the GAS conventions a nice guy The Martin Wheel Co Inc 342 West Ave Tallmadge OH 44278 2166333278 18004627846 out of state 18002627846 in Ohio V Groove steel wheels Every wheel you39ve ever needed We use their quotV groove wheels for our car anneal l42 ers as well as our yolk on Wheels and furnace door wheels etc I don t know if there is a catalog as We just drive over there This is a local company but I m sure any major area near you has a wheel company Maybe not McKay Chemical Co 880 Paci c St Brooklyn NY 11238 718 7834340 Acid surface treatment Acid surface treatment for glass If you Want an even frost on large areas of glass use Jack Frost for smaller areas use Velvet Etching Cream The etching cream has been a favor ite of many students for years and it Won eat your hands off if you get any on yourself Be advised though neither of these products is meant to do deep glass etching They only do surface frosting Sepp Leaf Products 381 Park Ave South Suite 1312 New York NY 10016 Phone 212 6832840 Gold Leaf Products For gold leaf and gold leafing supplies This company has a video on gold leafing for beginners There are also two books on the subject Gold Leaf Techniques by Le Blanc and Practical Guilding no author Grafo Colloids Div Metal Lubricants Co 105 Eighth St Emlenton PA 76373 Colloidal graphite This product is called Grafo Hydrograf it is a colloidal suspension of graphite It can be thinned with Water and sprayed or used in any degree of fluidity It dries and forms a graphite barrier between plaster metal etc and molten glass It can be used in sand cast ing to keep sand from sticking to the glass Sandblasters and Casting Sand Econoline Manufacturing Inc 1750 Elizabeth NW 143 Grand Rapids NH 49505 Phone 616 4546527 This company manufactures several models of self contained sandblast units These beauties are very common to the many glass studios throughout the US of A We have one at school and have had years of excellent service One thing that s good about them is that they come complete with a dust separator The models to look at are RA361 General purpose sandblaster This model is 36 x 24 RA 482 Same as above except that it is 48 x 24 RA48 x 48 CE You guessed it 48 x 48 inches square and very heavy duty Call Econoline for the distributor nearest you Please note that you will need your own compressor to run any sandblast unit A 5 HP 2 stage compressor is the minimal size you want Kraber Industries 1601 E 30th St Cleveland OH 44114 tel 216 6217048 This is the local disuibutor for the Econoline sandblasting units as well as a host of other brands It also sells other materials for sandblas ng Sand Blasting Tip No pun intended Sandblast your casting with ground comcobs available from your sandblast materials supplier to clean the surface without affecting the glass If you use a recyclable blaster be careful how much sand you clean from the surface as the sand will mix with the corncob recirculate and abrade the glass surface Shells Inc 350 State St Wadsworth OH 44281 tel 2163351565 Olivene Send This is a regional company that sells Olivene Sand for sand casting Check your yellow pages under Foundry Supplies for this product Olivene is not a silica product and is not as dangerous in causing silicosis It is great for detail and is very recyclable It is used like any other sand casting sand by dry mixing with 4 to 7 Bentonite 6 Wax The KindtCollins Co 12651 Elmwood Ave Cleveland OH 44111 144 216 2524122 1800 3213170 out of state 18003621160 in state Fax 216 2525639 Branch offices in New England New York West Coast M waukee and Canada This company makes waxes for sculpture Victory brand microcrystalline Jewelry etc etc etc It is the queen of wax companies It will formulate any kind of wax you need My students had a moldable wax formulated for them This Wax can be used like clay The only stipulation on special formulations is that you buy 100 lbs 0 The catalog is a must E Walnut Hill Enterprises Inc Green Lane 8 Wilson Ave PO Box 599 Bristol PA 19007 Phone 1800 NEED WAX for orders Yes that39s really their number Office and info 2157856511 Much cheaper than KindtCollins and works just as well 145 Footed Vase probably from an Egyptian tomb of the New Kingdom Period 14002360 act Photo courtesy the Corning Museum of Glass Glass vessels suddenly appeared in tombs of the Egyptian Warrior Pharoahsquot of the Eighteenth Dynasty They were ei ther piliaged from Canaan or Mesopotamia or were obtained as tribute during the period of Egyptian rule over portions of western Asia Such sophisticated glassware was produced in Egypt by foreign artisans during the peaceful reigns of Pharoahs Amenophis It and Aithenaten Egyptian glassware production declined thereafter and had ceased by the beginning of the Iron Age after i200 acr3 which coincided with the first Israelite settlements in Canaan 86 0 Were the Glassrnakers Samuel Iiurinsky Forty years ago I became the American market ing consultant for several Muranese verrerias Art glass was little known in the United States when I began promoting Venetian glassware in this country I lectured to interior decorators designers and architects on the history of Vene tian glassrnaking While researching that history for my lec tures I was surprised to learn that glassmaking is unique among the arts in that the process appears to have been invented only once in all of human history Some 4300 years ago about 2400 years 13ca Mesopotamian Akkadia sup plied the chernical and pyrotechnical womb in which the art of glassmaking was conceived and born There is no convincing evidence that glassrnaking independently arose anywhere in the world other than there in what is today lower Iraq Akkadia happens also to have been the pre surned birthplace of the biblical Abraham The earliest samples of manufactured glass known to exist come from area of Ur the city in which Abraham is said to have been born I was mystified by the fact that for several thousands of years thereafter glassmaking emerged suddenly at points around the world where the requisite pyrotechnical knowledge did not exist Furthermore what at first seemed to be a curious coincidence was that glassmallt ing consistently materialized in these areas at times coincident with the appearance of certain descendants of the Akkadians the Jews From 2400 to about 1800 13ce glassrnak ing was practiced only in Akkadia For the next three hundred years the art moved up the Tigris and Euphrates Rivers into Ararneia the birthplace of civilization and of the tribe of Abraham During the period from 1500 to 1200 aca glassmaking disappeared from Mesopotamia to be practiced only in Canaan The art became fixed in that small corner of the globe for another six hundred years Canaan became the states of Israel and Ju dea In 733 aca the Assyrian warlord Tigleth Pileser captured and deported thousands of Israelite artisans into Upper Mesopotamia The art reappeared at that very time in the ancient region from which it sternrned Europe as we shall see was entirely igno rant of the art until the advent of the Corn Inon Era Before my investigations began I had no idea that there had been any historical associa tion between the Jews and the art of glassrnallt ing The intimacy of the Jews with the art of glassrnalting turned out to be but the tip of the iceberg It became clear that the Jews were in fact integral to a long roster of basic industries They were ironmakers gold and silversrniths tanners dyers weavers and sericulturists The list of disciplines that Jewish entrepreneurs and artisans practiced is long and impressive They were particularly seminal to the pyrotechnical disciplines It is not for nought that the sur names Glass Glasser Glassman Gold Gold smith Goldner Goldstein Silver Silverrnan Silverstein Eisen Eisenberg et al remain Jewish surnames to the present day After my retirement thirteen years ago I followed the trail of the Jewish glassrnakers through the diaspora For eight years before the publication of my book The Glrzssmakers An Odyssey ofrhe Jews I explored archives in Egypt Turkey Italy Israel France and Britain The deeper I went into the subject the more surprising was the evidence that came to the surface I learned that Jewish artisans had migrated around the Adriatic Sea to fire the first furnaces in Venice I learned that a crusader the Mar quise de Montferrat installed Jewish artisans from Palestine into his fief at Altare in Pied mont Italy I learned that the glassmakers of Amsterdam were Jews In about 1650 the Dutch artist Jacob Van Loo recorded just such a group of Jewish glassrnakers at work As I continued my investigations the facts becarne ever more intriguing I discovered that few and possibly no ancient Egyptians Greeks or Rornans ever made glass or even glassware despite the fact that thousands of artifacts are credited to these cultures in museums the world over Were the Jews really the exclusive glass makers in the world over so manycenturies If so why is that association absent from our histories It is clearly impossible within this paper39s limits to document the scores of parallel paths along which the Jews and the art of glassrnallt ing traveled It will focus on one stop along those routes Rome Glassrnalcing arrived in Rome from Judea and Alexandria The myth that glassrnaking was born in Egypt has now been dispelled although it continues to be asserted by those who blindly parrot the discredited literature of the past Glass the raw material was never made in ancient Egypt There was one brief period in the reign of Arnenophis III when glassmaking suddenly appeared then contin ued during the short reign of his heretic son Akhenaten The glassware was certainly pro duced by Canaanite artisans from imported glass rods or tubes In the period irnrnediately following these incidents of glassworking there are traces of a few other minor instances where some glassware was made in Egypt Other glass ware found in Eighteenth Dynasty tombs were obtained as tribute or were looted from Canaan and Mesopotamia Every trace of glassware production disap peared from Egypt for more than a thousand years after this brief period Its disappearance curiously coincides with the biblical date for the exodus of the Jews from Egypt Glassrnallt ing does not reappear until the Alexandrian period when under the Ptolernies Jewish glass makers returned to settle in that new city on Diatreta vessels collected from an ancient glass making site near present day Kihbutr IIagoshrim Upper Gaiiiee Israel the Egyptian coast How do we know who those Alexandrian glassware makers were We have the testimony of two emperors that in the Roman world the Jews of Judea and Alexandria were exporters of glassware In the year 301 Diocletian issued a price fixing edict for imported products In the edict glassware prices were specified for only two areas of the empire one was Alexandria designated vim Alexandrfni and the other was Jttdea which was specifically designated vim Ijudaici that is Judaic glass The use of the name Judeaquot is curious The name had been officially expunged 170 years earlier by Hadrian as punishment for the revolt against Rome by the Jews The entire near eastern area was reconstituted as the Provincia SyroPalestinequot It is obvious from the use of the term Ju daic glassquot in the Diocletian edict that it was so ingrained into the vernacular of the times that it became a generic term for glassware from that region The derivative term quotJewish glassquot remained generic for the product in Europe for centuries thereafter as Jewish glassrnakers es tablished themselves throughout the Roman diaspora In England lead glass continued to be termed quotJewish glass into the midnineteenth century What about the second class of glass prod ucts Diocletian had defined vim Alexarzdrini These products were confirmed by Hadrian himself to be of Jewish production Hadrian wrote to his consul in that city quotThe Jews in Alexandria are prosperous rich and fruitful 88 and in it no one is idle Some are the blowers of glass others makers of paper all are at least weavers of linen or belong to one craft or an other the lame have their occupations the wounded have theirs and not even those whose hands are crippled are idlequot Thus the glassrnakers of both Judea and Alexandria were identified by Roman emperors as Jews Significantly quotPhoeniciaquot does not figure in the Diocletian edict at all indicating that although Sidon and Tyre were ports from which glassware was shipped the manufacture of glass took place in the hinterlands of Eretz Israel the land of Israel Etymology provides significant clues to history Clearly a product is known by the name of the group that created it Glass was first referred to in ancient languages as melted stone The earliest distinction made between mined and artificial gems is in the Akkadian language The Akkadian word for lapis lazuli was ugtm As early as the seventeenth century BCE the Akkadians distingushed between ztgnu sndi and ugnu kttri that is lapis lazuli from the mountain and lapis lazuli from the fire The distinction passed through all the Semitic lan guages Akkadian Assyrian Ugarit These were the very languages from which Hebrew derived It was not until two thousand years after the art was born in Semitic Akkadia that the first reference to melted stone appears in a western language Greek That distinction still does not name the material itself The Hebrew word for glass Zakmklzit goes back to a seventeenth century BCE Akkadian text In contrast no Latin word for glassquot existed for the first five hundred years of Roman existence The Latin word vitnmz appears for the first time in a speech by Cicero in S4 BCE in reference to an import from Alexandria Greek was also devoid of such a word The Greeks added their noun end ing os to the Hebrew word kltal meaning quota crystalline sand That adaptation formed the Greek word for glass hyczlos Ancient Egyptians never developed a word for glass they used the Akkadian term Glassrnaking technology was already 2400 years old at the birth of the Roman empire It became known to the Romans only after they had launched their campaign to conquer the Near East and after they occupied J udea and Alexandria W A Thorpe the English glass historian states that before that time To the Greeks glass was something new to the Romans something unknown Roman law precluded the Roman upper classes from engaging in lowly labor As con querors Romans of rank were prohibited from engaging in the rigorous perverse sweaty toil that the production of glass and its products entailed Cicero wrote a didactic treatise for his son in 44 ace quotVulgar are the means of liveli hood of all hired workmen whom we pay for rnere manual labor he declared for in their case the very wages they receive is a pledge of their slavery Cicero emphasized his repugnance by restating that All craftsmen are engaged in a lowly art for no workshop can have anything appropriate to a free man Only land manage ment was recognized as a suitable occupation for a Roman so long as slaves or serfs sweated Fragment of a giass vessel from Aquileia depicting Abral1arn39s sacrifice of Isaac nd The facade of the temple of Jerusalem stamps this fragment with Judaic character Nonetheless it has been designated paleoChristian by unobservant scholars Aquileia may be the first site where glassmaking occured on the European continent doing the work that needed to be done The agronomic exception still exists as a cultural carry over in our language today We still do not speak of gentlemen merchants gentlemen artisans or gentlemen rnanufacturers only gentlemen farmers are accorded a niche in genteel society Plebian Roman sentiments reflected those of their noble peers and were comparable to those of modern Americans towards ditch dig ging or stoop farrn labor that this is work fit for illegal immigrants from thirdworld coun tries The Romans were no different in this re gard than were the Greeks whose culture they absorbed The antipathy toward physical labor permeated Hellenic culture Blue blooded Plato relegated artisans to the lowest social stratum of his ideal society Aristotle inculcated his pupil Alexander with the proposition that the finest type of city will not make an artisan a citizenquot Xenophon juxtaposed Greek pride in noble military functions against contempt for the in herently ignoble occupations of artisans He stressed that quotGreek citizens are prohibited from practicing crafts where Greeks are in mili tary control Thus even if the Greeks and Romans knew the secrets of glassrnaking they were prohib ited or socially constrained from practicing the art The product was admired the producer was disdained After Augustus 27 t3ce l4 ce conquered Egypt he demanded glassware as part of the tribute What he was given did not satisfy him so he ordered that Alexanclrian artisans be brought to Rome to establish the art Pliny tells us that Alexandrian artisans founded glassmak ing facilities on the coast in 14 ca in Campania an area just south of Rome The first glassrnak ing furnaces in Rome were undoubtedly con structed in Trastevere quotacross the Tiberquot along with other sooty and odoriferous industries such as metalsrnithing unguent manufacturing and the tanning of leather all of which were mainly if not exclusively occupations of the Jews Until the Middle Ages the bridge over the Tiber was called the Pans Judaeomm the Jew39s Bridge which led to the Via del Picmto the quotStreet of Lamentationquot the heart of an area that later became the ghetto A charter issued in 1019 by Pope Benedictus VIII designated the area ftmdum integrzmi qui voccrtur Judaeorum quotthe entire district named after the Jewsquot 3 The area before the gate to the port out of the district was known as The Jew s Fieldquot until the seventeenth century The Trastevere district was traversed by the Appian and Latin Roads the bridgeheads for communication with the great harbor of Puteoli Much of the trade with the East was handled in Puteoli The Puteoli synagogue Acts 2813 and 14 stood on the quotStreet of G1assmakers 3 Trastevere was the industrial area of Rome where no Roman lived or worked It was however where the Jews lived and worked Thirteen Jewish congregations in Rome have already been identified from tombstone in scriptions The oldest synagogue of Rome the congregation of the Severians dates back to about 200 t3ca Trastevere was a dreary slum area with crooked streets and dingy workshops The gold goblets from which patricians drank the weapons of war Roman soldiers wielded the clothes the Romans wore the clcgantjew eled ornaments that graced Roman women all were produced in the scores of Jewish workshops lining the lanes of Trastevere Not until 1885 under King Victor Immanuel was the abolition of the ghetto decreed For those 1800 years the Jewish artisans of this crowded smokefilled quarter supplied the exquisite arti facts that now adorn the shelves of museums under a Roman39 label Jewish artisans spread into Europe behind the Roman legions and the art of glassmaking extended through Gaul and as far as Cologne in Germany The ruins of two early synagogues in that city attest to the importance of the Jew ish presence The historian Frederick Neuberg pointed out that quotThe oldest settlement in Ger many was in Trier a ghetto and the first glass houses of the Rhineland were founded there After Trier the oldest ghettos are in Cologne and Andemach and it is significant that the 90 oldest estab1ished glasshouses in Germany are likewise those in Cologne and Andernach 5 One of the objects retrieved from the ruins of ancient Cologne was a goldglass plaque ornamented with a depiction of a rnenorah the Jewish seven branched candelabra The menorah was similar to that pictured on an other plaque found in the Jewish catacombs in Rome complete with a funerary inscription ending with the Hebrew word shalom Equiva lent goldglass plaques are found in various collections some of which depict the facade of the temple of Jerusalem It was not long before Jewish artisans were found in every important urban center of R0 man Gaul and Germany Thorpe reports that the Semitic artisans had their quarters in the great industrial cities with the family tradition of their successors at Altare Murano and in Normandy they combined a willingness to migrate a fervent sense of parenthood a racial solidarity a genius for selling semitic qualities that no other glassinakers ever possessedquot Thorpe continues to relate that by the late Roman period in Nice Marseille Orleans Bourges Treves and above all Paris they were the leaders in the professions of law and medicine and in the arts ofjeweler goldsmith and silversrnithquot The German glass historian Axel V011 Saldern concurred noting that Syria Palestine remained the cradle of industrial glassmaking due to the invention of glassblowing A1exan dria continued to produce luxury glassware and Naples Rome northern Italy southeast ern France Cologne and other cities along the Rhine could also claim an efficient industry established mainly by Jewish glassrnakers who emigrated from Palestine sic in the first century The Jewish population of the Roman em pire numbered seven million ten percent or more of the entire population of the empire The sheer numbers of the Jews dispersed throughout the Roman empire bespeak their importance in the life of those times far beyond that generally accredited them They were not in the hinterlands but at the ports and produc Glass artifacts labeled neoAssyrian from a mu seum in France The use of the term neo Assyrian evades identifying these objects as Judaic glassware tion centers the industrial and commercial core of the Western world The impact of Jewish artisanship upon the burgeoning Christian society was so profound that their dominance of the arts was seen as a threat to the establishment The secrets of the arts especially glassmaking remained confined to those who practiced them This impelled St Jerome to author a treatise in which he warned that Roman society was being subverted by dependence on Semitic industry Glassmaking is one of the trades St Jerome bitterly lamented by which the Semites captured the Roman worldquot2quot The humiliating dependency of the Roman social order on Jewish artisanship engendered a humbler attitude toward labor The church was spurred into pragmatically launching a program for replacing the Sernites Guilds were formed and placed under the protection of specialized Christian saints San Filiberto for example was designated the patron saint of the glassrnakers of the Urtiversita d Altare The Jews were given a choice convert or be barred from their trades Conversion was how ever unevenly enforced because no substitutes existed for certain skilled craftsmen Sometimes Jewish glassmakers were given specific exemp tion from conversion In Cologne for example where the guilds succeeded in barring Jews from almost all crafts glassrnaking was made a unique exception because no other qualified personnel was available Do our museums acknowledge the Jewish glass makers for their creative works in Cologne It would seem that the church could not convert the Jewish glassrnakers of Cologne but our scientific institutions have succeeded in chang ing their ethnicity with the use of obfuscating terminology The Jewish glassmakers of Cologne have mysteriously been converted to Syrians Time and time again Jews were expelled from various areas only to be recalled when the economies of the regions suffered adversely by their absence Some of the glassmakers eventually converted others sought greener pastures to the east and south and never returned As long as the art of glassmaking remained in Jewish hands it grew in artistry and applica tion The exclusionary laws contributed sub stantially to the advent of the Dark Ages upon Europe Thorpe has pointed out that the decline of the art of glassrnaking was brought about by the growth of anti sernitisrn in the Merovingian Gaul during the 5th and 6th centuries The glass industry suffered high class models disappear when antisernitic propaganda was most intense One reason why this history came as a surprise to me and I am certain will come as a surprise to others can be attributed to mislead ing labels in museums and to misleading ter minology in literature Do we not assume from a label reading Roman glassware that the item was made by a Roman I posed this ques tion to the director of a prestigious museum quotEveryone knows that what we mean is that the item was made in the Roman periodquot he answered Not soquot I countered A student would assume from the label that a dyed in the wool Roman produced the item and he would reflect that fallacy in his thesis Thus the misconception becomes perpetuatedquot I am pleased to report that labels in that museum now read Roman periodquot Other museums to their credit are beginning to apply that scientificallyjustifiable phrase to glassware recovered from areas under Roman rule It was gratifying to see that the Coming Museum of Glass s catalog by David Whitehouse formerly entitled Romrm Glass in the Corning Museum of Glass was sensitively reissued under a new justifiable title Glass of the Roman Empire in the Corning Museum of Glass The actual producers of that glassware however remain to be identified Misleading labels are not confined to the Roman period There is a peculiar propensity to obscure the artistic and technological contri butions Jews have made to civilization it is a process I have termed quotinstitutionalized obfus cation It is glaringly evident in the patently unscientific and anachronistic treatment of objects made by Jews in their own country It is a remarkable fact that objects labeled quotIsraelitequot or Judaicquot are hardly to be found in museums anywhere in the world notwith standing that Israel and J udea were sovereign nations Judea endured as a nation for twice the age of the United States From its inception in about 1000 ace to the time the Babylonians occupied the country in the sixth century Judea had all the attributes of a sovereign nation For almost five centuries Judea had its own lan guage territory continuity and government Yet one searches in vain in literature and in museums for objects designated as Judaic Judea retained its national identity for an additional seven hundred years under Assyrian Babylonian Greek and Roman domination Each conqueror recognized dealt with and referred to Judea as a nation under their rule Judea was thus a continuous national entity for 1200 years Few other nations can match that twelve centurylong record yet we search in vain through museums and literature for an object made by Judeans The Judeans it would seem never even made a pot to piss in In my surveys of Israel I found twentyone sites where glassware was produced Most of these sites were previously unknown or have been ignored In nine of those sites I found evidence of all stages of glassmaking including frit and other partially vitrified materials Many of these were sizable remnants still attached to pieces of a crucible or a furnace The detritus of glassmaking furnaces was so plentiful that the crusaders used it for building material Items produced in ancient Israel and J udea are labeled SyroPalestinianquot Syrianquot or quotPalestinianquot in utter disregard of the fact that such entities did not exist at the time The term SyroPalestinian was coined by the Romans in 135 ca after the Bar Khochba revolt to legiti mize the destruction of J udea as a nation Ob jects produced in Judea over a period of more than one thousand years prior to that date can not correctly be labeled Syrianquot quotPalestinianquot or quotSyroPalestinianquot We look for parallels in the labeling of the products of other cultures occupying the same region during the same period We find none Edomite objects are never referred to as Syro Palestinian nor are socalled quotPhoenicianquot artifacts labeled as such Philistine or Nabatean products are never identified with such spuri ous anachronistic labels Yet none of the na tions or cultures that occupied the area dubbed quotSyroPalestinequot by the Romans had endured anywhere near as long as did Judea Other nations and cultures under foreign domination are universally credited with their products and accomplishments The Dutch ruled Indonesia for centuries Would any scholar in his or her right mind consider terming Balinese products as quotDutch Artquot Would one consider labelling Navajo Indian products as quotUnited States of Americanquot art Can one say that the products of Mayans are Spanish or Mexican Although scientists would never consider such spurious labeling they appear to have no com punction in ignoring the five centuries of Judaic sovereign existence let alone the twelve centu ries of national existence The Jews remained a cultural entity for another 1800 years complet ing a distinct coherent and continuous cultural existence for over 3000 years Some museums are kinder They avoid the anachronistic labels by the use of quot neoquot Neo Assyrian vessels in the museum in Milan Italy for example are dated to the eighth to sixth centuries BCE Glassworking no longer existed in Egypt If they were not made by the Israelites deported to Assyria they could only have been made in J udea Hadrian did away with the Judaic entity in 135 CE yet Roman emperors continued to refer to quotJudea The term vitri l rdaici was still in use a century and a half later by Diocletian Why then do the archaeological and scientific com munities insist on going so far beyond Hadrian and Diocletian by deleting Judea s previous 1200 year existence through their use of pa tently inappropriate anachronistic terminology Latent anti Sernitisrn should be excised from scientific nomenclature The archaeologi cal and scientific communities must face up to the shameful manner in which they continue to use obftiscating labels and must begin effect ing these long overdue changes Just as we rec ognize the Edornites Phoenicians Nabateans et al for their unique contributions to civilization so should we acknowledge the contributions of all deserving conquered peoples among them the Jews Scientific literature is after all obliged to accurately reflect cultural provenance We should become sensitive to the issue We can begin by changing obfuscating termi nology and labels One of the ways we can acknowledge our heritage as a gift the Jewish glassrnakers carried to the West is to cease using the anachronistic unscientific palpably spuri ous terrns Syrian Palestinian Syro Palestinian and the obfuscating prefix neoquot Further we must bring to the attention of those who un wittingly employ those terms or employ them out of common usage that they are not only unscientific but in fact covertly antiSemitic Samuel Kurinsky is the author of The Glassniakersz An Odyssey of the Jews and The Eighth Day and has lectured throughout the country on the his tory ofglassmakzhg Mr Kurlrzsky now retired was president of Irzterzzational House Inc USA mar keting consultants for Venetian glass artiscms in the United States He was also Executive Director of Vem39m39 US A and Vearr USi As an areheologist he has identified mrmerous glassmakfng sites in Israel and is an authority on the early history of glass in Italy Notes 1 Sir Charles Leonard Wooley Ur Excavations II 1934 p 366 2 Dan Barag Recent Epigraphic Discoveries Related to the History of Giasmaking in the Roman Period Ammles du 10 Congress MadridSegovle I985 pp ii3 l6 3 A L Oppenheirn The Cuneiform Texts Glass and Glassmaking in Ancient Mesopotamia 1970 p 10 4 C J Gadd and R Campbell Tliompson A Middie Babyionian Chemical Text Iraq 2936 pp 87lf S Cicero Pro Rabirio Posrumo An oration given in 54 ucts 6 W A Thorpe English Glass 1949 p 2 7 Cicero On Duties I xii II xxiv 87 xxv 8 Cicero op cit 1 150151 9 Aristotle Politics 332 10 Xenophon Oeconomicus 43 ll Pliny Natural History XXXVI p 194 2 David Philipson Old European Jewrics 1895 p 122 l3 Hermann Vogelsiein Thejews ofRome trans Moses Hades Philadelphia 1940 ll 3977 14 Leo Schwartz Great Ages and Ideas ofthe Jewish People p I18 Vogelstein The Jews ofRome p 27 15 F Neuberg Ancient Glass 1962 p 56 16 1bid p 70 17 Neuberg op cit in reference to descriptions of such goldglass plaques in Archives de l390rlertt Latin vol 1884 Chapter Vii pp 43965 Leopoidl Angelos Das Judisclze Goldglas Berlin 1928 See also Erwin R Goodenottgh Jewish Symbols in the GrecoRoman Period vol II illustrations 962975 Item 975 is presumably from Cologne 18 Thorpe op cit pp 397 8 ii 7 3 76 19 Axel Von Saldern Glas V0 der Aittike bis zum Jugendsiil 1980 D 19 20 St Jerome Comm in Exeklel xxvii in Pat Lat 25 313 Orbe Romano Occnpato 21 Salo W Baron Arcadius Kaiian ct al Econonuc History of the Jews ed Nachum Gross 1975 p 40 22 Thorpe op cit p 77 P0 11 AH gg z f39ecgt 500 455 Pipe Mc blea quotquot39quot 39quot l393 Ponei 439J and working the glass 3rd milleniutn BC Beads and amulets made by pinching rolling and other plastic means of shaping the glass I goo BC Sandcore glasses I630 I720 35 century BC The glassmalter s tube in troduced composite moulds used and tools which have remained un changed to the present day The glassrnaler s bench or chair comes into use ancient techniques resumed thread glass and the mille ori technique inVenice Bohemian balustet goblets with en closed tears in Potsdam twist stems also with enclosed thread twists in Bohemia and Silesia Goblets made in quantity to be cut and engraved 1745 7o Goblets with air twist stems in 1300 1802 1820 1821 1830 1859 1831 1886 1897 I898 1898 1905 1920 England later in the USA Glass pressed in England and USA Charles Chubsee of Stourbridge de vises an iron mould which folds to gether to be opened mechanically The technique of ashing is per fected in Bohemia Method of blowing with an air pressure pump invented at Baccarat Threepart moulds The British patent a machine for blowing bottles which can make 4oo bottles per day Fahdt s spring cage in Dresden Ashley and Arnall patent a machine for blowing bottles with preliminary mould and nished mould Boucher at Cognac builds a machine for making no bottles per hour Owens experiments sudsing in hot glass to feed the blowing mad ne W J Miller39s fully automatic press at Swissvale USA Bods s US patent for a machine for blowing bottles with a turning tank First fully automatic bottle with double moulds by M Owens Out put xo2ooo bottles every 24 hours zoth century Automatic manufacture of hollow glasses is used to make seam less moulded thinwalled goblets 313 a 39 39 39 quotquotquot39 1 f U 39 quot 1a sJI 1 wu aw u lt1 V quotW 39 39f M nun e uu 3939quot IH Development of the technique of fusing 13751358 BC Arnarna period glass fused at two levels in crucibles over open fire 6 669633 BC Asshurbanipal s clay tablets name arsenic as a purifying agent and tinoxide for rendering glass opaque 1023 Hrabanus Maurus s encyclopaedia with a drawing of a furnace r540 and 1556 Biringuccio and Agricola describe bell shaped furnaces 61 Glass fused With coal as the fuel for the rs timein England 1674 Jobst Ludewig builds the usual type of German furnace in Potsdam G 1675 Glassoflead or intglass in Eng land 168 3 d1alk glass in Bohemia Sdniirrost in Bohemia and France English crystalglass cone furnaces 1816 Robert Stirling takes out patent for glassfurnace heated by the regen erative process 1840 Description of a Belgian furnace with grate ring 1 840 Cros eld discovers the flame furnace forerunner of the tankfurnace 1857 Friedrich Siemens uses regenerative ring for glassfusing furnaces 1857 F Siemens builds a furnace in Berlin fired with gas as used for lighting 1858 F Siemens builds a water glass fur nace at Liesing near Vienna heated with generator gas 1860 H and F Siemens design first periodic tankfnrnaces in Saxony and Eng land 1867 The first continuous tankfurnace for fusing glass designed by F Sie mens in Dresden I371 Soda first made by Solvay s process 1885 Siernen s tank with freely developing ame zoth century Potfurnaces are used to fuse smallish quantities of di erent glass es They are mostly Biirten furnaces heated by the regenerative pro cess increasing tendency to use round furnaces heated by the recuperative process Highpowered tankfurnaces are used for fusing large quantities of a single type of glass working of the glass is automatic 322 300 Glasses of the pre Christian era The tnaiority of early glasses are Egyptian sand core vessels of closed form Bowls have been found in the tomb of Amenhotep II that is as early as c 1437 11 B C It is not known how they were made 970r The sand core glasses were stonelike and opaque but Sargorfs vase from Assyria second row right 722507 BC is sea green and transparent Ancient recipes inscribed on clay tablets record that arsenic was used as a re ning alloy in the fusing of glass Since the later Hellenistic luxury glasses bottom row right found in Asia Minor Ephesus Gordian and Apulia Canosa as well as the glasses blown with the tube page 31 were all transparent it can be taken as certain that knowledge was passed from Assyria to Syria and Alexandria The rst row shows glasses of the period rsoo970 B C Egyptian ktater arid lenticular bottle Mesopotamian bottle from Ur The second row illustrates glasses of the period of the Phoeni cian traders between 750 and 3oo B C alabastron pointed amphora aryballos and right the vase of Sargon King of Assyria the rs glass vessel not to be made over a core The third row shows glasses of the Hellenistic period 300 3o B C right the bowl from Ephesus and above it a bowl from Canosa 22 Roman domestic glass The discovery of glass blowing in the first century BC in Syria made it possible to produce glasses in great quantity to meet the demand created by Roman civilisation These included drinkingvessels and winebottles balsamaria for the baths and beakers with circus scenes Syrian glass manufacturers with an eye to business set up branch establishrnents in many parts of the Roman Empire Many of the glasses carry their names which were incised in the moulds used as part of the process of blowing I l quotJ I quot lts l39 l9quot Yxiiix ff l k quot3 ls ti n JJ J v quotgf xquotg rgt1 fgzrr39quotrrquotr39 r 1 l 100 200 The first row shows examples of the three ways in which blown glass could be made a Syrian beaker made in a mould throughout the whole process a freeblown Syrian balsamarium a jug with a celery handle first blown in a mould and then finished freely Second century specimens lotus bud beaker optically blown bottle lekythos Third century specimens beaker with fused glass drops bottle with grapelike bosses jug with handle Fourthcentury specimens beaker with coloured drops in the German taste bottle with handles in the form of dolphins jug with hoops signed Fron Frontinus 31 Luxury glasses of the Roman Imperial period Precious glasses masterpieces of the glass blower vitrearius or the glass cutter diatrezarius were made in Alexandria Rome Aquileia and Cologne Some of them are famous pieces whose fortunes are of interest They were made among other purposes for burial rites and as prizes for the victors at the circus games or gladiatorial combats For important commis sions Alexandrian glass was preferred at any rate in the form of raw glass which would be nished by the diatretarii At the time of Severus Alexander AD 222235 Egypt which was bound to pay tribute to Rome was still obliged to settle part of her incotne tax in glasses The medallion shaped glasses with gold inserts fondi d oro found in the Roman catacombs must also be counted among the distinctive glasses of the Roman Imperial period 100 200 300 Specimens of the first century AD bowl of the pterotos type vase with camemengraved decoration vase and cover Specimens of the second century facet cut beaker cup with snaltethread decoration kantharos forerunner of the glass cup Specimens of the third century beaker decorated with shell sh motifs Lycurgus s beaker bottle forerunner of the Kuztrolf Specimens of the fourth century Situla Pagana cup decorated with shells diatreton 35 Teutonic glasses The customs and the sense of form of the Teutons was the determining factor in glassrnaking north of the Alps during the period 400 yoo BC These Franltish glasses are for the most part drinking beakers blown from greenish brownish glass and later also from blue and amber coloured glass without handle or foot and neither cut nor painted The only decoration is grooving or threading The Teutonic custom was for the drinker when he had ernptied his glass to stand it on its rim in order to ward of the evil eye The rims are rounded except for the drinking horns in which they are sharp Frankish glasses extended mainly over what is now Belgium the RhineMain region Britain southern Norway and the island of Gothland Teutonic in uence had been apparent as early as the third century cf page 31 in the coloured eyes and wolf teeth which were supposed to a ord protection against demons 500 600 The illustrations Show the following examples dating from the fifth century S39rmzbed9er with inlaid white threads a bell cup a small grooved Spitzbedaer afier the Roman pattern a Ri sselbedaer Sixthcentury pieces grooved Sturzlveciher two bowls large Spitzbedaer with applied threads Kuztrolf Seventh century pieces tumbler stem glass Kugelbeoher beaker with inlaid threads drinking horn with applied threads and a bottle 39 71yr Oriental glass 7o7 Great Mosque at Damascus with glass mosaic 836883 Sarnarra the residence of the Abbasids lustrepainting 19o117o Works in rodscrystal and engraved glass in the Fatimid style G in Cairo Ioth1 Ith cent lustrepainting in Cairo at its peak 13th cent Enatuel painting on glass at its peak in Aleppo Damascus Raqqa and under Matnluk rule I253 Hulago Khan conquers Baghdad Art forms subject to Mongol in uence c 1280 Aldrevandinus of Venice P and other Franlsish glassrnakers employed in Syrian glasshouses export glasses with Christian motifs and arms 1317 and 1370 Syrian enarnelled glasses and coloured glass exported to Venice gilt glassware to Asia Minor Autalya I402 Tarnerlane conquers Damascus Glassmaking declines 1474 Sultan Kaithai Damascus imports glass mosque lamps from Venice 1517 Aleppo and Damascus cease pro duction the Crusaders t644 I667 Chardin a Venetian gives account of glassrnaking in Persia 1o62 Treasure of the Caliph Mustansir plundered in Cairo 1o95 Pope Urban II preaches the Cru sade Io99 Conquest of Jerusalem I102 Cup of Holy Grail taken from Caesarea to Genoa I187 Sultan Saladin reconquers Jeru salern I204 Enrico Dandolo conquers Conl stantinople which is occupied until 1261 Byzantine glasses to San Marco 1229 Jerusalem becomes Christian by treaty 1144 Ayyubids nally reconquer eru salern I 277 Treaty between Venice and Antioch Enarnelled glasses with Christian in scriptions from Syria The 111 of Edenhall readies England 1291 Acre Tyre Sidon and Beirut the last Christian strongholds con quered by the Marnluks Christian pilgrimages CI to Jerusalem continue until x4oo beaker of St Eig berg c 14oo I569 The Grand Viair Mohammed Pasha orders 90 mosque lamps of threaded glass from the Vene an ambassador in Istanbul 15871629 Shah Abbas in Isfahan patron of glassmaking glass industry set up in Shiraz main tained its importance into the 18th cent 68 and the Christian west Soo Ornamental window with Sdawarzlot painting at S rylesMezieres 9tl 1I 3th cent Glass made in monastic glasshouses 803 85o 895 Ecclesiastical prohibition on the use of glass chalices for the Mass 9oo Mattheus Vitrearius the monk and artist in stained glass at Reidtenau c 95o Theophilus Schedule dioersarum artium 1066 Abbot Didier brings glassmakers from the east to Monte Cassino to85 Archbishop Raymond sets up in Toledo an institute for translating Islamic works of learning I090 Endowment for stained glass of Chartres cathedral xo9t Michael Scotus in Sicily translates Aristotle s works and works on alchemy from the Arabic ttoo Five windows portraying prophets in the cathedral at Augsburg 1134 Bernard de Clairvaux prohibits the use of stained glass windows by the Cistercian Order I3tl391 cent Glassmaking becomes independent of the church glasshouses making Waldglas grow up north of the Alps 13th cent Glass cullet imported from Venice to make alchernical apparatus in Germany 1273 Gothic nave in Strasbourg Minster 1275 1282 1295 Venice prohibits the export of g1ass cullet alurn and sand emigration forbidden I279 Venetian guild of glassrnalsers founded 1232 Duty on German pedlars of glass in Venice r317 First Venetian tradingvessels in Bruges Antwerp and Middelburg 1406 Charter of the guild of glassmakers of the Spessart 39 under Count Ludwig Von Rienedt 1453 Greek Byzantine glasstnakers driven out by the Turks flee to Venice 1454 and 1547 Families of Venetian deserters liable to arrest 1486 Niclas Waldt of Vienna rcceivesa licence for a glass house in the Veneto 1490 Venetian armorial glass for King of Hungary 15o8 t524 Peter Manson a Swedish priest writes Glaskonst 1518 Merchant families of Augsburg Nuremberg and Ulm order armorial glass Fngger from Venice I54o Biringuccio Venice writes Pirotedmica I 5 o Glasshouse at Antwerp on the Venetian pattern 1556 Agricola Chemnitz writes De re metallica I562 Bergpostille by a Lutheran Mathesius in joadtirnstal 1612 Antonio Neri Florence writes L arze vezmria 69 Islamic glasses EGYPT SYRIA Early Islamic Blown glasses in all possible techniques and decorative cutting K g bz as in the Byzantine period Modi cation of forms D Coloured glasses with patterns made in one with the body impressed or applied Cut glasses 3 also coloured facetcut glasses MESOPOTAMIA PERSIA Early Islamic Blown glasses in all possible techniques and decorative cutting Kugefxrb1 as in the Sassanian period Modi cation of forms Lustrepainting Cameoengraved glasses with animal motifs and ornaments also 2 959 l 4 incised decoration Fatimid 1055 1037 Blown glasses with Blown glasses Seljuk extremely thiri walls 5 Cameocut glasses and also coloured glasses glasses cut in intaglio as before with impressed or Enam ed e applied patterns glass also L Sm Pmlung 9 coldpainted 5 Engraved glasses copied from and gut lasscs rockcrystal prototypes Sc kgs Hadxjgxgi ser H1 W Emsquot fr 1227 1256 Mongolian with red outlines 0 i also gilt Painting shows I Chinese in uence 9 o also in Syria m 39I the art of glass making in the 16th century 3 3 8 S jm 1502 Safavid Blown glasses all one colour in elegant shapes Pg Stagnation sets in at the end of the 1811 century 73 Forms of Spanish glasses Oriental and Islamic in uences and the use of Venetian techniques are recognisable in the popular glasses which remained duaracteristic of Spain until the eighteenth century and some of which are still being made today In the eighteenth century Spanish glassmaking merged with the general European development 1600 1700 Top row Southern Spianish glasses of x t IIUNIIIIIMIIacvv t uvvmamm II 4hIIIIII nun 0 quota m v 39IH39I o n u uuvnuuouuwnuu Pm 393 MItrn iquot39quotquotquotquot p quot39 P quot r nI t I n t 3939 39 dd P quot4 Iii 39393939 Wig V IN um 39lt i 139 ii a 391 Iquot 3 l quot bottle or porrdn small bottle 4arm 39n39 F1 a quot39p 3913939 aquot hi 1 a the x6th 17th century Funnelbeaker or jarrita rose watersprinltler or almorrazxes vase Second row Venetiazrin uenced Catalonian glasses of the 17th century Vase with applied owers wine glass with lazticino threads enamelpainted bottle Third row Catalonian glasses of the 18th century Vase jug or c nzaro drinking 75 39 quot39 1Aw rrVrww w Gothic glasses of northern and southern Europe The Gothic Whldl rst emerged in the thirteenth century in the buildings of northern France also produced the earliest evidence of glass on French soil These extremely scarce early Gothic glasses are forerunners of the populer green Waldglas decorated with dropped on spots which greatly increased in numbers in the course of the fourteenth century 1300 I400 1500 13th century Kopf from Sdiw ibisdu Hall c 1280 goblet found at Liege standing bowl found at Rouen bottle found in Poitou 14th century Nuppenbedaer from Normandy wineglass from Rouen two early Gothic forms of the Angster or Kurtrolf First half of the 15th cen tury Maigelein tall glass with dropped on spots double cone bottle Veneiian bottle Second half of the 15th century jug Sdzeuer c1ub shaped glass Kraurstrunk Venetian goblet made of blue glass with enarnel painting bowl First half of the 16th century beaker jug Nuppenbeoher with foot Venetian goblet and cover gilt with enamelpainting blue jug beaker 92 Genealogy of the drinking glasses of today The forms of drinking glasses may be traced back to the fourteenth century Models drawn from the ancient world and from the orient were elaborated in an original manner during the Gothic and Renaissance periods The green Waldglas is printed grey in the diagram below Colourless giass took its place in the 17th century The only exception is the Riimer which today still shows traces of its green origins The diagram begins with antiquity the period from which the first vessel dates top le The tradition of antiquity lived on in Syrian and Venetian glass Northern Europe was in uenced by the Syrian bealsers brought bad by the Crusaders while to some extent the Venetians went straight bad to ancient prototypes 5 Syn O O 0 O 0 3 I40 0 O 0 Q 0 0 0 0 0 C 0 O 0 o C 0 o o c Venice 0 O O O O C 9 O Q 0 O 1500 Krautsrrunk aniytill G03 1 1711 Renaiss u Footbeaker R5 39 ma Keulertglas quot s 395 r F 235 3939quot3 39 1600 2 i g IIFEXW39U397UhFquotroKMJv zothc Winvglass I aging R5ter O Wareglass The above diagram illustrates the developtnent up to the late Renaissance only when the basic features of the present day forms were already clearly apparent Later stylistic varia tions are shown in diagrams further on in the book 94 M Y Renaissance forms Venetian glasses in the Renaissance style date from the second half of the fifteenth century Gothic in uence remains apparent until I 525 there are no more monodmrorne coloured glasses after the end of the Gothic period Venetian awareness of antiquity produced highly distin guished forms while delight in experimentation created numerous variations both of which mark the new Venetian crisrallo I w un vuuvnultwz quotquot 3L2KZ 39AFquot 39I 139C 39s39u t239I239 Z d4rquot39u39maooI1v39 4ono man21 v A39I90quotU1I392 t039v39r 239MvtIoas249I 12 quot 39 I A 1 quot 39 39o439 39391 i 39quot39Ir 3939 quot 11 el3 3 Distinguishing features of Renaissance glasses include the blown stems hollow balusters and hollow knobs and the folded footting The Venetian cristaflo is of a pale strawawcolour Enamehpainting between c 2460 and 1530 only 98 Venetian glasses and glasses in the fagcm de Venise Towards the end of the sixteenth century Mannerist features begin to appear these become more obvious in the glasses of the seventeenth century and are apparent in northern wares in the fagon de Verzise as well The twisted thread decoration of the winged stems and the wings io the shape of the double eagle are found outside Venice only p quot 39oJ 397quot I u I esA39 39mV quot39 I wow 39 f 39hquot 5 39 r fv 1 et39u iHl 391Lup39 quot JU pasI il of 39quot3939n quot uh 39 uquot u 339 Z3 u3939n339i 39hquotvk I 3f mm u m ugtgtqI w11 unite 14y 3 I quot n v 2 ml quot r uquotquotquot Vt J39na3939hN39 39 4quot 39r 4 7 D zxtm NW H ltVI u39 V fllquotquot quot Mr 1 1 u quot 4 ll amp 439 I I a H at 395 quotH1 2 u Glasses from Venetian glasshouses in northern Europe 99 Waldgl iser and their descendants to the I 8th century The in uence of the Renaissance was not felt in northern Europe before c 2530 The applied drops used in the decoration of Nuppenbecber disposed vertically during the Gothic period were now arranged diagonally and the drops themselves were atter The vast Humpen the measure of the mighty thirst of the period became the most usual form of drinking glass In the Netherlands the R mer attained a gigantic size Waldglas with enarneldecoration made its first appearance c 15 3o x 5 so and remained popular until the 18th century The designation Waldglasbiitte or forest glasshouse is justified only until the time when the travelling glasshouses became established in one place or until the period when manufacture came under the protectorship of the prince This happened in the x7th18th centuries The notion of Waldglas however remained in use until as late as the 18th century as the quali tative designation for green glass First row bowl below it Krautstmmle beaker Passglas Igel hedgehog glass Second row glass of the Saxon court cellars glass with pendant rings Kuttrolf bottle Third row Hcm pen with Imperial eagle Romer from the Netherlands glass with thumbimpressions s i I 1600 O Baroque forms Distinguishing marks of the Baroque are the baluster stems ef the goblecs and the ba1l feet of the beakers The stems of the goblets are squat and massive The footrings and rims are engraved Stems ballknops and knops on covers as well as the lower part of the bowl are all facetted or pseudo facetted stems of Thuringian glasses Domed feet are typical of Hesse and Lauenstein Jaw Q 1 i F2 f ul 1 x if T33 39 quot 39 G 110 g 188 Rococo and Louis Seize By about the mid18th century the forms become more graceful Engraving is the prevalent form of decoration and Silesian work is outstanding Sweetmeat dishes on tall stems are typical39During the last quarter of the century NeoClassicism gained ground with new formal elements The principal form of the Louis Seize style is the goblet on a square foot Opposite page First row shows early Baroquc forms beaker painted in Sobwarzlot by Johann Schaper Nuremberg I665 rnarbled gobl39 frorn Grimnitz in the Udtermarlt dated I602 glass of a Dresden shooting gallery Saxony dtted 1678 Second row High Baroque Beaker and cover made of ruby glass with engraved scene by Gottfried Spiller Potsdam c 1700 Bohemian goblet c t7oo Silesian earnemengraved goblet c tyoo Potsdam goblet and cover with acanthusleaf frieze and lozenge border 171525 Bohemian beaker and cover with interlaced StI393pWOI li and foliage c 1720 Third row Late Baroque Silesian goblet c 1742 Lauenstein goblet with domed foot Thuringian goblet and cover with pseudo facetted stem and knop on cover engraved by G E Kundtel 1726 goblet and cover with airbubbles in the facetted knops rout1d headed border with oval eyes Zedtlin t76o Saxon goblet and cover with balusterstem double knop tear and skilbfacets Above First row Rococo forms ambrosia dish Silesia c 1750 Silesian goblet and cover c 176 Hessian goblet and cover c t75o Berlin goblet with portrait of Frederick II Silesian bottle with goldpainted decoration Second row forms of the Louis Seize style Zechlin beaker Bohemian goblet Silesian beaker and cover with silhouette medallionportrait bead border cellular facetting on the bowl and square plinth I89 In the cours developed original rmly based forms Airtwists and twists of milk white glass became popular during the second half of the century Facetting was in general use between 1760 English glasses e of the 18th century English glasses broke free of their Venetian models and and 1810 1700 1725 1760 rtvv V 39 039 f 99 39 9 4quotav 4 u First row Chalice of Mansell s period c 1642 Flint glass 2 t68o jug attributed to George Ravenscro c 1630 Pundrbowl Second row Cordial glass Chalice of soda glass c 1735 Dram glass c 170 Sweetmeat glass with dentatcd rim Third row Champagne glassChalice Wine glass 2 1750 Cordial glass Fourth row Wine glasses with aimwists and twists of milltwhite glass glasses with facetted stems that on the right with vertical utes at centre of row a dram glass 24 1830 Empire and Biedermeier forms Nineteenth century glasses are always cut The final shape is in many cases only achieved by deep curring Following upon the NeoClassical forms of the goblet and urn so common during the Empire period small beakers predominate during the Biedermeier period The imitations of earlier styles which characterise Historieism current from 1830 until 1893 continee throughout much of the century Empire forms Berlin goblet with scalloped foot and brilliantcutting dated 1825 Bohemian beaker with brilliantcutting and cylindercutting c 1830 um made at Baccarat 181020 Bohemian Kuglergracur 132o beaker by Samuel Mohn 182 doublemedallion beaker by Mildner 1806 Biedermeier forms Knopfbedaer made of lithyalin 183040 Hyalirh beaker c 1830 ashed beaker with cut decoration c 1840 Ran bedyer by Korhgasser c 1828 cut glass beaker c 1842 bowl with foot brilliantcur decoration c 1840 The forms of Histori cisrn Etruscan vase Medici vase both c 1840 247
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