1. BASIC COURSE IN PRINTING TECHNOLOGY

2. The main Printing process
Letter press
Offset Lithography
Gravure
Flexography
Screen Printing
Other Reprographic process

3. Letter Press Letter Press is a relief process
The image is reversed and it is non readable
The process uses metal type which is hand set or machine set
Pictures are made from blocks made of photo engraving.
Inks are tacky and drying by absorption, oxidation
Used 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 mix
The image and the non image are in the same plane.
There are three basic cylinders
Plate cylinder (Image carrier – readable)
Blanket cylinder (carries the image)
Impression cylinder (transfers Printing)
The inks are tacky and it is Thixotrophic in nature
Can Print on relatively rougher surfaces
The inks dry by absorption and by oxidation and polymerisation

6. Offset Lithography
Most commonly used press where the number of impressions are any thing from 1000 – 50 ,000 copies.
Sheet fed - cartons, folders, magazine covers
Web offset – magazines , news papers etc
Low preparatory costs when compared to other process
Operation 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 inks
The inks are carried by the cylinder and the excess ink is wiped by the doctor blade
The impression from a rubber roll makes the ink to transfer to the substrate through capillary action
The image is non readable
Mostly economical where the run length is very high

10. Gravure
Most 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 high
Requires very smooth surface as the image is direct contact with the substrate
Also good compressibility ensures better printing
Produces a continuous tone effect in the image

11. Flexography
A form of relief Printing uses rubber or resilient plastic plates ( photo polymer plates)
The inking system uses a special annilox roller immersed in liquid inks
Inks dry by evaporation
Uses water based inks and is most friendly for food packing applications
For 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 inks
Used for very short run job as the initial cost is less
Used for printing visiting cards, textile printing etc.

13. Printing a job
The ad agency or the customer prepares a rough layout or dummy
The customer gives the copy for reproduction which can be text matter, line drawings, photographs etc
The customer prepares a mechanical layouts which shows the position and others which is called art work
The type setting is done

14. Photographic Originals
Quality and Productivity
Litho – Offset Print Production
Photographic Originals

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
Text
ABCDEFGHIJKLMNOPQRSTUVWXYZ
abcdefghijklmnopqrstuvwxyz

18. Quality and Productivity Litho – Offset Print Production
Digital Originals

19. Printing a job … contd
The photographs, pictures which are continuous are scanned.
The text and pictures are combined as per the art work
After these they are assembled to make a negative
Depending on the plates, negative or positive is exposed with the plate to give the Plate for printing

20. Printing a job … contd
The plate is developed after exposure and is mounted on the printing machine
The printing takes place with the help of the ink and the image from the plates
After printing post printing operations like cutting , varnishing, punching are done

21. Colour theory
Additive primaries – Blue , green, red – The combination these three coloured lights give white light. The principle used in TVs, computer monitors etc
Subtractive primaries – Maganta, cyan, yellow –The combination othese three pigments/dyes give black – Used in printing, painting etc

22. Colour Measurement
Human Vision

23. Additive Colours

24. Colour Measurement
Colour Monitors RGB
RGB RG GB G RB R B K

25. Colour theory
4 Colour printing – A picture is scanned and four positives of cyan , yellow , maganta , black are taken
Cyan – Red filter
Maganta – Green filter
Yellow – Blue filter
Black 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 picture
The half tone process is done through screens in printing.

31. Paper Properties and their relation to Printing
Caliper/Bulk/Density
Determines the pressure required to get good Print
Uniformity in caliper to minimise variation across the sheet
Bulk/density determines the print reproduction in direct contact process
Creasing and folding property

32. Paper Properties and their relation to Printing
Smoothness/Roughness
Determines the ink transfer and dot reproduction on the surface
Final Print gloss and Varnish Gloss
Dot Gain

33. Impact of smoothness and Coating
newsprint
coldset
art paper
glossy inks

34. Quality and Productivity Litho – Offset Print Production
Dot Gain
Dot size on
scanners display
Dot size
on print
Dot gain

36. Paper Properties Colour
Expressed as Whiteness, Brightness and L, a, b values.
Print colour reproduction (shade Matching)

37. Paper Properties Moisture and Dimensional Stability
Runnability in web feed process
Blistering in Heat set web offset
Register control in sheet fed offset
Folding and Creasing

38. Paper properties Tensile Strength Pick strength
Runnability in web feed process
Pack formation in flexible laminates
Pick strength
Ability to take high tack inks
Ability to run at faster speeds

39. Paper Properties Water Absorbency Ink Absorbency Ink drying
Dimensional stability
Ink Absorbency
Post Print gloss
Pick strength

40. Thank you