Rotary printing press
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A rotary printing press is a printing press in which the impressions are curved around a wheel so that the printing can be done on long continuous rolls of paper, cardboard, plastic, or a large number of other substrates.
Today, there are three main types of rotary presses; offset, rotogravure, and flexo (short for flexography). While the three types use cylinders to print, they vary in their method.
Offset lithography uses a chemical process which an image is chemically applied to a plate (generally through exposure of photosensitive layers on the plate material).
Gravure is a process in which small cells or holes are etched into a copper cylinder which are filled with ink.
Flexography is a relief system in which a raised image is created on a typically polymer based plate.
In stamp collecting, rotary press printed stamps are sometimes a different size than stamps printed with a flat plate. This happens because the stamp images are farther apart on a rotary press which makes the individual stamps larger (typically 1/2mm to 1mm).