Offset Printing- An Introduction

The offset printing mechanism uses three cylinders to move the image onto the substrate. Offset printing uses printing technique where the inked image is transferred from a plate to a rubber blanket, then to 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 image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a film of water, keeping the non-printing areas ink-free.

The process of offset printing need a large investment in equipment and set up. However, once the infrastructure is in place, offset printing itself is rather inexpensive.

Types of Offset Presses

Offset presses are mainly of two types:

• Sheet - Fed : In this type of offset press the printing is passed out on single sheets of paper as they are fed to the press once at a time.
• Web - Fed : In this type of offset press the printing is carried out on a single, continuous sheet of paper fed from a large roll. The sheet is then cut into individual sheets of desired sizes. There are many more differences between the various types of offset presses.