Color Offset Printing
Offset printing is still the most common method of producing printed paper products, whether they be brochures, letterhead, direct-mail pieces, catalogs, magazines, books, newspapers, etc. It is especially the preferred method for nearly all large quantity print runs. Digital printing is continually becoming more popular and a cost effective (for small quantity and non-color-critical) option for many types of projects.
We’ve been asked many times what the word “offset” means. The answer is simple, and just needs a little understanding about how a conventional printing press works.
The offset printing process (also called ‘offset lithography’) uses printing plates - one for each color ink to be printed - to transfer an image onto paper. These plates are typically metal or a plastic substrate, are thin and completely flat, and are rolled around a cylinder and secured.
The image that will be printed is put on the plate using a photo-mechanical or photo-chemical process, and is a negative image. The lithographic process - based on repulsion of oil and water - prints only the image that is on the plate due to the chemical makeup of the ink and solutions involved in the process. The plates receive ink from ink rollers, and the non-image area on the plate attracts a water-based solution called “fountain” solution, which keeps the image area free of ink.
A “blanket” is also required in the offset process, and is a rubber substrate which is also rolled and secured around a cylinder. The word “offset” comes from the process wherein the inked image is transferred from the plate to the blanket, and then the blanket transfers the image (inked) onto paper. As the image is not directly transferred from the plate onto the paper, it is referred to as “offset”.