I. What Is A Blanket?

Definition: A blanket is made up of two parts, the carcass and the rubber face. The rubber face is the coated elastic surface, which carries the image to the paper during the printing process. The carcass is the backside of the blanket and is specially woven to maintain the integrity of the blanket.
The printing blanket plays an integral part in the printing process. The blanket carries the image being printed from the inked plate to the final impression on the paper.

The rubber face must be free of nicks, pinholes, low spots, bumps or gauge variation for the printed impression to be produced clearly and precisely.

II. Blanket Characteristics

Blankets typically are available compressible or conventional. Compressible blankets are the most common and widely used blankets in today’s press shop. One of the main reasons for this is due to the forgiving qualities compressible blankets maintain. Conventional blankets are less forgiving, but allow for a more uniform dot formation.

There are two surface characteristics; cast and buffed. Cast is the traditional surface type. Cast is smooth with a tolerance of .002. Blankets with a cast surface are available in conventional and compressible. The buffed surface is coarse. The coarse surface requires an extra finishing process during manufacturing. Buffed surfaces carry more ink, have a quicker paper release and tighter gauge control (+/- 0.001).

III. Understanding Blankets

Blankets are cut specifically to meet the needs of the blanket roller on a press. They must be mounted with the pinstripe on the carcass going around the cylinder. Blankets have an around and an across direction. The around is always stated first when giving a size.

Blankets are mounted with the pinholes or bars going along the across direction. Blankets can be mounted on the press in several different ways. Pinholes that go into sprockets, bars that get mounted by clamp, straight edge blankets, which require that the press have a special mounting mechanism (except for sticky backs).

IV. Common Blanket Problems

Pinholes, low spots, smashing, gauge variation and bubbles. Except for smashing, the other problems are usually manufacturing related.

V. Blanket Care

The surface of a blanket is very delicate; therefore it is important to handle printing blankets with extreme care.

Blankets should be stored face-to-face (rubber to rubber), or back-to-back, in tubes rolled up tightly or laying flat (except for sticky backs). Do not place blankets in direct sunlight or near a heat source for any length of time. When unpacking blankets take care not to cut through the tube and into the blanket. Blankets do not have a shelf life when stored properly.