A non-reversible, permanent depression in or compression of any portion of an offset press blanket, caused either by a smash or by a lack of resilience, in which the blanket is unable to retain its original thickness following the exposure to the extreme pressures generated during printing. (See Blanket and Smash.)
'Compression set is also used to refer to a permanent reductioin in thickness of a rubber flexographic printing plate, the distortion being represented as a percentage of the original thickness of the rubber surface.