Below is a range of information about printing and the services, technicalities and activities carried out within it.
Prepress is defined as: ‘The art, process, or business of producing printed material by means of inked type and a printing press or by similar means.’
Offset litho printing process
Offset lithography comes essentially in two forms, sheet fed or web offset.
The process works as follows. A printing plate is clamped round the plate cylinder inside a press. This is flanked by a blanket cylinder and a number of smaller rollers called inking and damping rollers.
Ink and water do not mix and whilst the plate cylinder rotates the inking and damping rollers distribute ink and water over the plate. The water acts as a carrier for the ink as it rests in suspension in the water.
On the plate imaged and non imaged areas either attract or repel the suspended ink.
The inked plate then ‘offsets’ the image onto the rubber blanket cylinder, to form a mirrored or wrong reading image.
Concurrently a sheet of paper has been transported to the impression cylinder, where it is pushed hard up against the rubber blanket cylinder, where the image is again offset onto it.