printing

Question 1

offset lithography process

Answer 1

• printing plate made from flexible aluminium and put on a plate cylinder
• water added to the plate that repels the ink so it only goes in the right areas
• transferred to a rubber roller to avoid wetting the paper
• ink it put onto the paper
• repeat for other colours

( the printing plate doesn’t touch the paper, it is offset so goes through the offset cylinder first then the paper)

Question 2

offset lithography pros/cons

Answer 2

pros - quick, low unit cost, high quality, oil based inks repelled by water - principle of OL

cons - paper cant get wet or print wont work, only flat prints, paper must come in flat, expensive set up, no water based inks

Question 3

flexography process

Answer 3

• plastic or rubber plate is made with a raised surface
• plate fixed to a plate cylinder
• fountain roller dipped in an ink reservoir
• transferred to a anilox roller
• ink coverage is regulated with a doctor blade
• transferred to the print cylinder
• pressed onto paper between the print cylinder and compression roller
• repeat for other colours

Question 4

flexography pros/cons

Answer 4

pros - paper can bend meaning the machines can be smaller, high speed, can print on many materials

cons - no fine detail, inconsistent colour possibility, expensive even though it is the cheapest

Question 5

screen printing process

Answer 5

• add photosensitive ink where you don’t want the print to be made, cure in light to make a mask (photo emulsion)
• jigs used to line up the screens
• use a squeegee to make an even layer of ink
• remove the frame and leave to dry
• repeat for other colours

Question 6

screen printing pros/cons

Answer 6

pros - cheap, easy to use, easily customisable, quick to make a prototype

cons - slow rate of production, very manual

Question 7

digital printing process

Answer 7

• squeezing an ink droplet out of a nozzle to charge it
• falls between two oppositely charged plates to the ink, that control where it falls
• thousands of ink droplets make up the image

Question 8

digital printing pros/cons

Answer 8

pros - fast, can print anything without having to change or make plates

cons - much lower quality print

Question 9

Gravure process

Answer 9

• copper plate is made with grooves where the ink sits, added to a printing cylinder
• submerged in an ink reservoir and a doctor blade removes ink from the raised surface leaving it only in the grooves
• rolled onto paper between an impression roller and the plate cylinder

Question 10

gravure pros/cons

Answer 10

pros - consistent colour, high quality print, fast, used for mass printing

cons - expensive plates mean only long runs are cost effective, expensive set up