TEST Study guide 2 - GC 440
TEST Study guide 2 - GC 440 GC440
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This 12 page Study Guide was uploaded by Allie S on Wednesday November 18, 2015. The Study Guide belongs to GC440 at Clemson University taught by Dr. Weisenmiller in Summer 2015. Since its upload, it has received 170 views. For similar materials see Commercial Printing in Graphic Communications at Clemson University.
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Date Created: 11/18/15
Exam II Study Guide, Fall 2015 Offset Press Feeder, Registration, & Delivery Systems GGPP, pp. 303-318 (pp.338-354 2 Ed.)nd · Describe the basic concept of lithography: -process invented by Aloys Senefelder, wanted to call it chemical printing, he could make parts of a stone repel ink and parts of a stone repel water -image carrier: A design is drawn with greasy crayon or ink on a flat limestone slab, to which the crayon adheres -dampening: The stone is then moistened with water which is absorbed by the parts of the stone not covered by grease -inking: Using a roller, greasy ink is applied to the stone - the ink adheres only to the drawing and is repelled by the wet parts of the stone -impression: A print is made by pressing paper against the inked stone drawing -drying: The paper and ink are allowed to dry · Compare and contrast Offset Lithography with Digital Print Systems in terms of quality, value, and productivity Offset Litho - Digital Print – HP Indigo Cheaper for LONG RUNS Better for SHORT runs Cannot print VDP, is Static CAN VDP Price per piece diminishes with quantity Finishes IN-LINE Leverages the power of VDP Web offset: higher set up cost, price per piece does down with quantity, heat or coldset inks, fast drying. Sheetfed: 18,000 iph, inks oxidize, slower dry time (24-48hrs) Digital: best suited for short runs (1,000 or less), variable data capable, 7,200 iph · Compare and contrast Offset Lithography with the basic process of Flexography • Costs more, higher setup, press costs, more complex: longer, more involved setup. Not as versatile in range of substrates, uses a planographic image carrier. · List and describe technological trends in press technology -Integrated computer workflow -increased inking capability -improved automation and controls -UV technology · Name and briefly describe three North American Print conditions. 3 print Conditions: 1. GRACoL - General Requirements for Applications in Commercial Offset Litho - For commercial offset printing (…………) 2. SWOP 3 - Specifications for Web Offset Publications - For publication printing (lower quality, newspaper, magazine prints) 3. SWOP 5 - Specifications for Web Offset Publications · Understand the aspects of print quality including: density, trap, · Describe the sheet feeding and registration system in terms of standard operating procedures and press mechanisms. Sheet Feeding: -feeds from the back of the sheet and pushes the sheet underneath the sheet that was fed before it -moves it forward a few inches depending on the size of the press sheet -the whole sheet does not have to move into place, stop, then be guided into final position -pull guide Register: -the positioning of the sheet relative to the image on the blanket -helps to determine "same place" -the overall agreement in the position and alignment of printing details on a press sheet Registration Table: -helps control the sheet -drive wheels and tail wheels -double sheet detector (optical and mechanical) -head stops · Explain the importance of the “register corner”. Offset Printing Unit Mechanics, Ink & Chemistry Handbook of Print Media, pp. 206-260 · Ingredients of lithographic ink o Colorant Pigments can be organic (natural) or inorganic (lab) o Vehicle Vegetable oil base (Linseed oil) Resin (Natural or hydrocarbon) o Additives Waxes, driers, etc. Drying agents (catalysts) Cobalt – top dryer Manganese – through dryer · Ink drying: how do common offset lithographic inks dry? Distinguish between “setting” and “drying” of inks. Ink Setting: -30 minutes to 2 hours -the top of the ink film dries enough to print again -to determine if ink has set, try to smear the ink with your finger and a light touch Ink Drying: -about 48 hours -ink dries by oxygen cross-linking with the help from driers -two of the main drying catalysts used to accelerate the ink drying process contain Cobalt or Manganese (Cobalt for surface drying and manganese for internal drying) -solvents will separate from the ink and bleed into the coating or paper leaving the varnish on the surface to cross-link with oxygen and harden · Tack: sequence, interaction with substrate, wet trap. What problems can occur if ink is incorrectly sequenced? Tack sequence is K-C-M-Y Measure Tack with an Inkometer Determine the tack/run sequence by laying down the tackiest to least tack inks If inks are incorrectly sequenced it can cause contamination of other units · List the main functions of the inking system of an offset lithographic press 5 Main Functions of Inking 1. Work the ink from plastic state to semi-liquid state o Offset inks are “pseudoplastic”--meaning, as the ink is worked over time, the shearing forces reduce viscosity o Thixotropy—refers to whether the pseudoplasticity occurs quickly or slowly relative to the ‘body’ of the ink. 2. Distribute a small thick film to an even, thin film all around the form rollers. o Nearly .00005 inch .05mils o Flexo ink film thickness = .0004in. (.4 mils) 3. Deposit a uniformly even, thin film of ink on the image 4. Pick up fountain solution from the plate, emulsify partially into the ink, and evaporate the rest The dampening process 5. It should pick up foreign matter and hold in suspension until the system is cleaned · Explain how is “impression” and “squeeze” adjusted between cylinders. -plate packing is used to underlay a press blanket or plate, to bring the surface to the desired height; the method of adjusting squeeze pressure -Squeeze .004”-.006” -Between the plate & blanket -Between the blanket & impression · Be able to label a diagram of our Ryobi 3305HA press. · Describe and diagram an Anicolor inking system uses an anilox roller and doctor blade type setup, ink is transferred directly to the roller. it enables printing without ghosting, reduced make-ready, and works with conventional plates · Explain how ink level is controlled on a litho press. · What is the composition of fountain solution? How is it measured and controlled. Fountain solution is an alcohol-based solution used to wet the roll Measured: -conductivity—1500 over water +/- 100 in our lab, carries the electrical charge -ph—buffers keep ph same, about 4.2/4.5 to 5.5; our tap is 7.0 (buffering salts) -ohms—measures resistance -micromhos—measures flow of electricity or conductivity Controlled: -fountain solution is a surfactant -a common problem in many press rooms is the excessive use of fountain solution concentrate -“conductivity” measurements can prevent that from happening Conductivity: -conductivity is the ability of a solution to conduct electricity -this is directly related to the quantity of dissolved material (concentration, or ounces per gallon, of fountain solution concentrate) -through experimentation, establish the concentration of fountain solution that performs best with your dampening system and printing requirements Imposition: · Explain the considerations of creating an imposition. Impositioning is the process of arranging the pages of copy so that when the sheets are printed and folded for binding the pages will be in the proper order Take into account pages that have an image that “takes up 2 pages”/carries over into the second page · Define Work and Turn/Tumble & Sheetwise impositions · Why would an imposition include a “Binder’s lip” · Know the terms: “head”, “foot”, & “face”. Head - “top” of page Foot - “bottom” of page Face - front/first side of page Head –to – head – printing on both sides of a sheet where the top of each page is placed at the same end. Head – to – foot – printing on both sides of a sheet where the top of each page is placed at the opposite ends. Heidelberg DI: · Explain the concept and review the demonstration video at Presstek.com · What a typical run length for a DI press? -500-20K -“Sweet Spot” = 500-5,000 · How does it compare to digital printing and conventional offset? -DI: 96,000pph -Conventional Offset: 288,000pph -Digital Printing: 14,400pph · Although the DI is not a ‘digital press’ per se (it is a hybrid press), what is the ideal run length of a true ‘digital press’? · Plate material · Waterless lithography advantages and disadvantages Advantages: -higher line screens for better image detail -better consistency throughout the run -higher tack inks; fast drying times -higher densities, better ink holdout, greater tonal range -makeready is cut in half -elimination of ink and water balance variables yields reduced running time and waste -better register control -elimination of paper stretch caused by fountain solution -elimination of hazardous VOCs and waste water Digital Offset Printing · Differentiate electrophotographic printing from/offset/high-speed ink jet/heatset web offset · The Indigo printing cycle (Reference pp. 6-7 in the document “HP Indigo Digital Offset Color Technology” found on Blackboard.) · What products may be printed digitally? Photo books Booklets (signature, squarefold and lay flat options) Brochures Posters Postcards Business cards Manuals Proposals Calendars Newsletters Trifold fliers Z-fold inserts Invitations Review the video demonstrations at: · https://www.youtube.com/watch?v=vl9-Jj4n858 · https://www.youtube.com/watch?v=TdWYXhG0rJ4 High-speed (wide format) Ink Jet Printing · Webfed HP T400 - Review the video demonstrations at: http://www.youtube.com/watch?v=AjIDOtRmf4A DI Technology · What a typical run length for a DI press? How does that compare to digital printing and conventional offset? -500-20K -“Sweet Spot” = 500-5,000 -DI: 96,000pph -Conventional Offset: 288,000pph -Digital Printing: 14,400pph · What does ‘DI’ stand for? direct imaging · Describe the plate material and the imaging process for a DI plate making system. · Describe the advantages and disadvantages of waterless ink. Advantages of Waterless Printing -reduced waste -shorter makeready -better ink holdout -better image detail -better consistency HP Indigo Technology & Electrophotography · HP Indigo: identify and describe the purpose of the main press components on a diagram of the Indigo 5000. · Read the white paper document (on BB): “HP Indigo Digital Offset Color Technology” · Explain how the print engine on an Indigo works. o How is an image generated? Stage 1 – image Generation o The assemblies taking part in the image generation stage are the: o PIP (Photo Imaging Plate) drum and PIP foil o Scorotron – PIP charging unit o Writing head o How is an image developed? Stage 2 – image development o The electrophotographic process uses a working dispersion ink. o The ElectroInk® is composed of three components: Ink pigments – negatively polarized Imaging oil™ - highly insulated Imaging agent™ Ink Pigments HP ElectroInk® contains ink pigments that are negatively polarized. When under an electrical field, the individual particles lock together. § The particles are directed using electrical fields to develop the desired image. Imaging Oil Imaging oil ™ is a highly insulative liquid. The ElectroInk particles are suspended in this liquid. The imaging oil acts as a liquid carrier for the ElectroInk particles and is the medium in which they move. Carries and makes ink spreadable Imaging Agent Imaging agent ™ is composed of active molecules that make the ink pigments reactive to charge. Makes pigment reactive to charge o How is an image transferred to a substrate? · What controls/monitors density of the electroink on an Indigo? · Why would you use one shot vs. multiple pass printing? · What are the ingredients of electoink? -ink pigments -imaging oil™ -imaging agent™ · In which order are electoroinks printed? Is this sequence able to be changed? YMCK - but it CAN be changed (remember that Litho is KCMY) · What is the format (size) of the HP Indigo 5000, HP Indigo 10000? HP Indigo 10,000 · 29-inch format (B2- back to paper) · 3450 sheets per hour (4/0) 4 colors on one side, 0 on the other · Up to 7 colors HP Indigo 5,000 (GODFREY) · 12 x 18 Format (2-up) · · Up to 7 colors · Be able to discuss basic print quality troubleshooting. Augmented Reality · What is Augmented Reality? -mixes virtual objects with a view of the real world -real scene by user + virtual scene by computer = AR · Name two AR applications. LBS - Location Based Services (ex: yelp) Aurasma Layar · Explain how an AR System works? -smartphone, tablet, or computer camera needed -app needed - download from App store -trigger needed - this is what causes the AR to happen (designed using the app software) -triggers need to be thought out and tested · What are the components of an Augmented reality system? Trigger - an image that when used by the AR App, triggers an overlay Overlays - any imagery that is triggered when using an AR app · Where can we see AR in commercial/marketing applications? Be able to describe an example of AR. · Explain how AR is used in tandem with print media. Provide an example. AR is a way of creating a user-interactive marketing. Ex: Ikea - letting prospective customers “try out” the furniture · Compare and contrast the advantages of AR to its barriers/limitations of proliferation? E.g.: Pro’s and Con’s of AR. PROS: -ease of use -practicality -measure of success -cost -possibilities CONS: - Need a SPECIFIC AR app to read, not universal Practical Points of Paper GGPP, Chapter 08 · Paper Math · Caliper: How is it measured? How is it expressed numerically/verbally? Paper thickness Measured with a caliper in thousandths of an inch · Basis Weight: Be able to define it. How is it used practically in paper selection? o Basis Weight – standard way of specifying the DENSITY of paper Basis Weight—a standard set for referring to the different papers within a classification. Basis Weight = the weight of 500 sheets of the basic size sheet for that class of paper Four major classes of paper (Basic sheet sizes): BOND – 17 x 22 TEXT – 25 x 38 COVER – 20 x 26 INDEX – 25.5 x 30.5 o M weight The M-weight is the weight of 1000 sheets of paper, any size. Paper is a commodity sold by thousand-weight. Shipping weight is a major expense. There is not always 1000 sheets per carton. Can have split cartons · Basic Sizes: Memorize the basic sheet sizes for Bond, Text, Index, Cover Know the Basic Sizes of: Bond, text, index, cover o Bond 17” x 22” o Text 25” x 38” o Index 25.5” x 30.5 o Cover 20” x 26” · Be able to draw out (diagram) a basic cutting plan (similar to the one that you used in lab for your press test).
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