Offset printing or web offset printing is a commonly used printing technique in which the inked image is transferred (or “offset”) from a plate to a rubber blanket, then onto the printing surface.
When used in combination with the lithographic process – which is based on the repulsion of oil and water – the offset technique employs a flat (planographic) image carrier (printing plate) on which the image to be printed obtains ink from ink form rollers.
The non-printing area attracts a water-based film (called “fountain solution”) ensuring that the non-printing areas are kept ink-free.