Printing Techniques Flashcards
Explain the process of Offset Lithography
-Camera ready copy produced with full use of colour calibration, registration marks and crop marks.
-Registration is key in ensuring four colours align for optimum image quality.
-Digital file is then separated into four separate colours (CMYK) which are then laser etched into aluminium printing plates.
-Plates are then connected to the plate cylinders of each colour system.
-Ink and water are used to ensure ink is separated from plates and dispersed onto paper.
-Impression cylinder ensures even print on to the paper.
-Paper is fed through and each colour image imprinted onto paper via the impression cylinder.
Advantages of Offset Lithography
-Print a wide range of colours when used for four colour printing
-It is a high quality process
-Very economical on medium to large production runs 500 - 500,000
-It is a fast process when working with large quantities– speeds of up to 50,000 presses per hour can be achieved on a web
Disadvantages of Offset Lithography
-Less economic than digital printing on small to medium runs 50-100,000 (although quality is slightly higher)
-Limited to the type of materials it can print onto – the surface must be flat.
-Can be a longer lead time due to the processing and production of printing plates.
-Higher set up costs so is only suited to large print runs.
What is a Registration Mark and what is it used for?
Registration marks are used to ensure the printing plates are aligned correctly
What are Crop Marks used for?
They define where the paper is to be trimmed
What is Colour Calibration used for?
To ensure the RGB to CMYK conversion is accurate
How is Colour Calibration planned?
-Using colour calibration bar the colour match between specified (CYMK) colours or pantone colours and the printed colours can be checked.
-Check that conversion from RBG to CYMK is accurate.
-Check the density or tint/shade of colours (using densitometer bar) can be checked.
-Suitability of ink drying rates on substrate can be checked.
-Amount of colour bleed on the substrate can be checked.
What is Laser Printing?
Repeatedly passing a laser beam back and forth over a cylindrical drum to define an image.
The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated in order to permanently fuse the text and/or imagery.
What are the advantages to Laser Printing?
-Laser printers cannot be beaten for black and white printing.
-Lasers are faster and better for large production runs.
-Laser ink dries quickly whereas ink form ink jets can smudge after printing.
-Laser toners dry quicker and handle UV light well reducing fading.
What are the disadvantages to Laser Printing?
-Lasers are generally more expensive and toner costs more.
-Laser cannot produce the same colour quality as Inkjet printers.
What is Inkjet Printing?
Recreates a digital image by propelling droplets of ink onto paper, plastic, or other surfaces
In the inkjet printing mechanism, the print head has several tiny nozzles (jets). As the paper moves past the print head, the nozzles spray ink onto it, forming the and images.
What are the advantages to Inkjet Printing?
- Inkjet colour is better than laser for full colour printing.
- Inkjets produce more vivid colours.
- Inkjet printers are more consumer friendly and used more by consumers.
- Hardware and ink is much cheaper for Inkjet printers.
- Can print on a wide variety of substrates
What are the disadvantages to Inkjet Printing?
- Inkjet printers are not suitable for large runs and are less economical due to the speed at which ink runs out, length of time prints take.
- Inkjets used wet inks and therefore can smudge after printing.
- Inks used in inkjets are prone to fading over time.
- Can’t print on a wide range of substrates as anything heat sensitive cannot run through them.
What is a Solid Ink System?
Uses solid wax inks that are melted into a liquid before being used.
Solid ink printers jet the ink onto a drum.
What are the advantages to a Solid Ink System?
-More economical as ink is used more sparingly when compared to inkjets.
-Ink quantities used are easily controlled therefore there is less wastage and lower cost for running.
-As the ink comes in solid blocks there is less waste as with inkjet liquid or laser toner. There is also less packaging required for solid ink blocks.
