describe the process of offset lithography
- UV light is used to transfer the image onto a smooth aluminium printing plate
- the image area is coated with a chemical that attracts the oily ink but repels the water (so non-image area holds water)
- the image is printed onto a rubber blanket cylinder which squeezes away the water+leaves the ink/image behind
- the ink is transferred onto the paper between the blanket cylinder and an impression cylinder
describe the uses & benefits of offset lithography
- fast and high-quality finish
- good for print runs of 1000+ copies
- books, newspapers, magazines, packaging
describe the process of flexography
- a flexible rubber/plastic printing plate holding the image (sticks out a bit on the plate) is applied to the surface with an impression cylinder underneath
describe the uses & benefits of flexography
- can be used to print onto surfaces that aren’t completely smooth
- quicker than lithography and the printing plates last longer
- used for large print runs 5000+
- cardboard, plastic bottles, packaging, wallpaper, carrier bags
describe the process of screen printing
- a stencil is put under a fine mesh screen
- ink is spread over the top of the mesh screen using the blade
- ink goes through the stencil and is printed onto the material below
describe the uses & benefits of screen printing
- low cost - ideal for short print runs 100-300 where detail isn’t needed
- can be used to print on various surfaces
- posters, estate agents signs, textiles, t-shirts
describe the process of dry/digital printing
simple:
a design is sent from a computer+ the printer recognises required colours and adds layers of cyan, magenta, yellow, and black (CMYK) to make the final colour
copying:
* master copy face down on glass top
* beam of light runs along top of copier/ master copy
* light reflects from white areas onto rotation drum, drum loses its positive charge in these areas
* toner attracted onto remaining pos-charged areas as drum rotates
* drum pulls apper through the machine, transfers toner onto paper and heats to set image
* releases printed paper
describe the uses & benefits of dry/digital printing
- less fiddly than printing plates, no set-up costs apart from buying the printer + ink
- is expensive per sheet but is cheaper for short print runs around 100 copies
- posters, flyers, digital photos, independent cafe menus
describe the process of gravure
- ink fills the gaps in an etched brass printing plate
- the image is transferred onto the material between the printing cylinder and an impression cylinder
describe the uses & benefits of gravure
- expensive set-up costs
- quick+ good for large print runs of identical copies
- produces higher-quality products than lithography
- postage stamps, magazines, photos in books
