Offset Printing

Offset lithography is a multi-step process that uses etched metal plates, water-repellent (e.g. oil-based) inks, water, blanket cylinders, and impression cylinders.

The plates are created so that oily inks adhere only to the portions of the plate that contain the images and text. A thin film of water over the blank areas of the plate repels the oil-based inks.

The ink on the plates is first transferred to a rubber-wrapped “blanket” cylinder. The ink reaches the paper when the inked blanket cylinder rolls over the paper.

Many presses use impression cylinders to apply pressure to the paper as the ink is applied to the paper surface. Impression cylinders also help move the sheets through the presses.

Offset lithography is the primary method used to print longer runs of magazines, books, manuals, brochures, direct-mail pieces, letterhead, posters, and paper-based labels and packaging.

Because of the fixed costs involved with setting up each job for offset printing, the cost of each copy in a 250-copy order will be higher than the cost of each piece in a 10,000-copy job.