Editing Rotary printing press (section)

== Types of rotary printing presses ==
[[File:Western Daily Press printing press 1908.jpg|left|thumb|'Annand' newspaper press, 1908]]
Today, there are four main types of rotary presses; [[Letterpress printing|letterpress]], [[Offset printing|offset]] (including web offset), [[rotogravure]], and flexo (short for [[flexography]]). Although all the types use [[cylinder (geometry)|cylinders]] to print, they vary in their method.

*Rotary letterpress printing uses type metal plates molded in the form of a cylinder. The plates, called [[Stereotype (printing)|stereotypes]], are coated with ink, then pressed against a continuous roll of paper. Rotary letterpress printing was used in the mid-twentieth century to print most major newspapers.
*In [[offset lithography]], the image is chemically applied to a plate, generally through exposure of photosensitive layers on the plate material. [[Lithography]] is based on the fact that [[water]] and [[oil]] do not mix, which enables the [[planographic]] process to work. In the context of a printing plate, a wettable surface (the non-image area) may also be termed [[hydrophilic]] and a non-wettable surface (the image area) [[hydrophobic]].
*Gravure is a process where small cells or holes are etched into a copper cylinder, which are able to be filled with ink. All the colours are etched in different angles, thus while printing every colour is placed in proper position to give the appropriate image.
*Flexography is a relief system in which a raised image is created on a typical 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 further apart on a rotary press, which makes the individual stamps larger (typically {{convert|0.5|to|1|mm|abbr=on}}).