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Rotary Printing Press

There are two type of rotary letterpresses, sheet-fed and web-fed. Sheetfed rotary presses are also declining in use; in fact these presses are no longer manufactured in the U.S. Web-fed rotary presses are the most popular type of letter press printing. These presses were used for high-speed work. In the oscillating press, the forme slid under a drum around which each sheet of paper got wrapped for the impression, sliding back under the inking rollers while the paper was removed and a new sheet inserted. In a newspaper press, a papier-mâché mixture was used to make a mould of the entire forme of type, then dried and bent, and a curved metal plate cast against it. The plates were clipped to a rotating drum, and could thus print against a continuous reel of paper at the enormously high speeds required for overnight newspaper production. As computerised typesetting and imaging replaced cast metal types, letterpress began to die out, as high-speed photographic imaging onto smooth flexible plates became more economical. However photopolymer plates and the invention of Ultra-Violet curing inks have helped keep rotary letterpress alive in areas like self adhesive labels. There is also still a large amount of flexographic printing, a similar process, which uses rubber plates to print on curved or awkward surfaces, and a lesser amount of relief printing from huge wooden letters for lower-quality poster work.

Further information and links:

Hoe Four-Cylinder Rotary Press
Rotary Printing Press