The Offset Litho Process

Offset Litho printing works on the principle that oil and water do not mix. A photographic image is transferred onto a thin metal plate which is treated so that the image area attracts oil based inks while the wet no-image areas resist them. This plate is then passed over rollers of a clean solution or water and then passed over inked rollers so the oil based inks “sticks” to the image area. The image is then transferred onto a rubber blanker which is then transferred onto the papers surface. Each plate prints a separate colour and dependant on the press size they can work in any combination of colours including pantone and metallic inks but mainly work in four colour process (CMYK).

Because of the upfront set up costs of the plates and the presses this makes Off-set Litho printing more beneficial to longer run print projects.

There are many types of Offset Litho printing presses available for example single colour, two colour, four, five, eight and ten colour with different presses being able to print on various sizes of paper from Oversized A3, A2, A1 and upwards.