Printing Processes

Lithographic Printing
The main printing process used throughout the world and encompasses a number of different terms including:

Offset Printing, Litho, Sheet Fed, Web Offset, Continuous.

It is a planographic process where the image and non-image are on the same flat printing plate. The image areas are processed to accept ink and repel water. The non-inage areas are processed to accept water and reject the greasy ink. So by wetting the plate and then inking it, the image area is able to transfer the ink to a blanket cylinder and then from there to the paper (the offset principle). The printing plate never comes into contact with the paper.

Litho plates are made by a variety of methods but most modern print factories use computer-to-plate (CTP) systems which are created direct from the computer files rather than having to output film first.

Digital Printing
Is primarily used for short runs of less than 1000 or for items that need to be individually personalised with text and/or images. Digital printing requires less set-up than other methods but does not gain from economies of scale.

Digital printing uses a dry ink process where the ink does not permeate the paper unlike wet ink. The dry ink is held in place by applying a layer of fuser oil and a heat process.

Large Format Printing 
This process uses inkjet printing machines that can print widths up to 3.5m and virtually any length. Large format printing is usually used to produce short run posters, banners and point of sale material and the end results can be lightfast and permanent.

Silk Screen Printing
This process uses a stencil which is mounted on to a fine screen material. The ink is passed through the stencil and screen onto the substrate.

Screen printing can be used on virtually any substrate and any shape using any kind of ink.

Flexography
This process uses a rubber plate and very thin inks and is similar to the original letterpress printing techniques. This is a specialist process and is used most commonly on plastic carriers bags.

Gravure Printing
This process uses an engraved image which is flooded with ink and the surplus is scraped off with a blade, the plate is then pressed onto the paper. This process can produce very intense colour on very low grade paper and so is a popular process for long runs like Sunday newspaper supplements.