2 The main Printing process Letter pressOffset LithographyGravureFlexographyScreen PrintingOther Reprographic process
3 Letter Press Letter Press is a relief process The image is reversed and it is non readableThe process uses metal type which is hand set or machine setPictures are made from blocks made of photo engraving.Inks are tacky and drying by absorption, oxidationUsed for printing bill books, wedding cards of smaller number say upto 1000 impressions
5 Offset Lithography It is a plano graphic process Uses the principle of oil and water do not mixThe image and the non image are in the same plane.There are three basic cylindersPlate cylinder (Image carrier – readable)Blanket cylinder (carries the image)Impression cylinder (transfers Printing)The inks are tacky and it is Thixotrophic in natureCan Print on relatively rougher surfacesThe inks dry by absorption and by oxidation and polymerisation
6 Offset LithographyMost commonly used press where the number of impressions are any thing from 1000 – 50 ,000 copies.Sheet fed - cartons, folders, magazine coversWeb offset – magazines , news papers etcLow preparatory costs when compared to other processOperation skill required is very high
8 Gravure Intaglio process – the image area is recessed The gravure cylinder where the image is etched ( image carrier) is immersed in a pool of liquid inksThe inks are carried by the cylinder and the excess ink is wiped by the doctor bladeThe impression from a rubber roll makes the ink to transfer to the substrate through capillary actionThe image is non readableMostly economical where the run length is very high
10 GravureMost common application are cigarette, flexible laminates, currency notes etc.The initial cylinder costs are very high which is justified only if the run length is highRequires very smooth surface as the image is direct contact with the substrateAlso good compressibility ensures better printingProduces a continuous tone effect in the image
11 FlexographyA form of relief Printing uses rubber or resilient plastic plates ( photo polymer plates)The inking system uses a special annilox roller immersed in liquid inksInks dry by evaporationUses water based inks and is most friendly for food packing applicationsFor large runs of liquid packaging, getting popularity in publishing abroad
12 Screen printing It is a stencil process Can print on any surface Uses high tack paste inksUsed for very short run job as the initial cost is lessUsed for printing visiting cards, textile printing etc.
13 Printing a jobThe ad agency or the customer prepares a rough layout or dummyThe customer gives the copy for reproduction which can be text matter, line drawings, photographs etcThe customer prepares a mechanical layouts which shows the position and others which is called art workThe type setting is done
15 Quality and Productivity Litho – Offset Print Production Artists’ Originals
16 Quality and Productivity Litho – Offset Print Production Graphic Originals
17 Quality and Productivity Litho – Offset Print Production TextABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
18 Quality and Productivity Litho – Offset Print Production Digital Originals
19 Printing a job … contdThe photographs, pictures which are continuous are scanned.The text and pictures are combined as per the art workAfter these they are assembled to make a negativeDepending on the plates, negative or positive is exposed with the plate to give the Plate for printing
20 Printing a job … contdThe plate is developed after exposure and is mounted on the printing machineThe printing takes place with the help of the ink and the image from the platesAfter printing post printing operations like cutting , varnishing, punching are done
21 Colour theoryAdditive primaries – Blue , green, red – The combination these three coloured lights give white light. The principle used in TVs, computer monitors etcSubtractive primaries – Maganta, cyan, yellow –The combination othese three pigments/dyes give black – Used in printing, painting etc
25 Colour theory4 Colour printing – A picture is scanned and four positives of cyan , yellow , maganta , black are takenCyan – Red filterMaganta – Green filterYellow – Blue filterBlack printer – Under colour removal
26 The process of printing The printing process is done through dots.The tonal gradation is achieved through varying the size of the dots but the number of dots remain same.The number of dots in a square area determine the resolution of the pictureThe half tone process is done through screens in printing.
31 Paper Properties and their relation to Printing Caliper/Bulk/DensityDetermines the pressure required to get good PrintUniformity in caliper to minimise variation across the sheetBulk/density determines the print reproduction in direct contact processCreasing and folding property
32 Paper Properties and their relation to Printing Smoothness/RoughnessDetermines the ink transfer and dot reproduction on the surfaceFinal Print gloss and Varnish GlossDot Gain
33 Impact of smoothness and Coating newsprintcoldsetart paperglossy inks
34 Quality and Productivity Litho – Offset Print Production Dot GainDot size onscanners displayDot sizeon printDot gain
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