printing Flashcards
offset lithography process
- 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)
offset lithography pros/cons
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
flexography process
- 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
flexography pros/cons
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
screen printing process
- 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
screen printing pros/cons
pros - cheap, easy to use, easily customisable, quick to make a prototype
cons - slow rate of production, very manual
digital printing process
- 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
digital printing pros/cons
pros - fast, can print anything without having to change or make plates
cons - much lower quality print
Gravure process
- 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
gravure pros/cons
pros - consistent colour, high quality print, fast, used for mass printing
cons - expensive plates mean only long runs are cost effective, expensive set up
laminating
encapsulation of the paper in a plastic wallet that is sealed and bonded to the paper with heat
spraying
coating the surface of the paper with a plastic, which is more durable than lamination as it bonds to the papers surface better
embossing and debossing
creating a raised surface (embossing) or a divot on BOTH sides of the paper (debossing) using dies that press the paper to shape and debossing thins areas of the paper
foil blocking
pressing foil onto debossed sections to increase contrast of the imprint or to increase the aesthetics, pressed using heat and pressure
varnishing
clear non pigmented ink that is coated onto boards or paper and soaks in providing a good bond and offers protection
spot varnishing
in certain areas varnish is applied to a similar cause to foil blocking to make words have a higher contrast
