Printing Plates
The plates used in offset printing are thin (up to about
0.3 mm), and easy to mount on the plate cylinder, and
they mostly have a monometal (aluminum) or, less often,
multimetal, plastic or paper construction. Aluminum
has been gaining ground for a long time among
the metal-based plates over zinc and steel. The necessary
graining of the aluminum surface is done mechanically
either by sand-blasting, ball graining, or by
wet or dry brushing.Nowadays, practically all printing
plates are grained in an electrolytic process (anodizing),
that is, electrochemical graining with subsequent