Wednesday, 29 September 2010

AT THE PRINTERS

Commercial print processes are technical, practical and economical.

Four printing processes we have looked into a little bit are:
  • Rotary printing
  • Digital printing
  • Screen printing
  • Pad printing
Rotary printing:


The three main types = Offset Lithography, Flexography and Rotogravure


In these processes, the printing plates are wrapped around cylinders. Print material can either be sheet fed or on rolls.


Lithography: (planographic)


Aluminium plates are etched intoand wrapped around a cylinder. The ink is transferred onto a rubber blanket roller and then print surface.

For a larger amount of prints, web press is used, which prints on a continuous roll of paper. This is typically used for newspapers or books for example.

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Flexography: (relief)


'A positive, mirror image rubber polymer plate, on a cylinder, transfers 'sticky' ink directly to print surface. Usually roll feed.'

 Flexography is very versitile and can print on many material, such as paper, plastic, metallic films...

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The relief plate used for flexography is molded rubber or photopolymer materials, with the image raised above the non-image areas on the plate.


The 'anilox' roller applies ink to the raised areas on the plate, and that is then transferred onto the substrate






Rotogravure: (intaglio)



Copper plates (with mirror image) transfers ink directly to print surface (usually on rolls).
The plates are durable, so good for long print runs.

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