offset printing


offset printing
Lithog.
offset (def. 6).

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or offset lithography or litho-offset

In commercial printing, a widely used technique in which the inked image on a printing plate is imprinted on a rubber cylinder and then transferred (offset) to paper or other material.

The rubber cylinder gives great flexibility, permitting printing on wood, cloth, metal, leather, and rough paper. In offset printing the matter to be printed is neither raised above the surface of the printing plate (as in letterpress printing) nor sunk below it (as in intaglio, or gravure, printing). Offset printing, a development of lithography, is based on the principle that water and grease do not mix, so that a greasy ink can be deposited on grease-treated printing areas of the plate, while nonprinting areas, which hold water, reject the ink. The offset plate is usually of zinc or aluminum or a combination of metals, with the surface treated to render it porous and then coated with a photosensitive material. Exposure to an image hardens the coating on printing areas; the coating on nonprinting areas is washed away, leaving wetted metal that will reject ink. See also xerography.

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▪ printing technique
also called  offset lithography , or  litho-offset 

      in commercial printing, widely used printing technique in which the inked image on a printing plate is printed on a rubber cylinder and then transferred (i.e., offset) to paper or other material. The rubber cylinder gives great flexibility, permitting printing on wood, cloth, metal, leather, and rough paper. An American printer, Ira W. Rubel, of Nutley, N.J., accidentally discovered the process in 1904 and soon built a press to exploit it.

      In offset printing the matter to be printed is neither raised above the surface of the printing plate (as in letterpress) nor sunk below it (as in intaglio, or gravure, printing). Instead, it is flush with the surface of the plate; thus offset is classified as a planographic method of printing.

      Offset printing, as a development of lithography (q.v.), is based on the principle that water and grease do not mix, so that a greasy ink can be deposited on grease-treated printing (printing press) areas of the plate, while nonprinting areas, which hold water, reject the ink. The offset plate is usually of zinc or aluminum or a combination of metals, with the surface treated to render it porous and then coated with a photosensitive material. Exposure to an image hardens the coating on printing areas; the coating on nonprinting areas is washed away, leaving wetted metal that will reject ink.

      Modern offset printing is done on a press composed basically of three rotating cylinders: a plate cylinder, to which the metal plate is fastened; a blanket cylinder covered by a sheet of rubber; and an impression cylinder that presses the paper into contact with the blanket cylinder. The plate cylinder first comes in contact with a series of moistening rollers that deposit moisture in the granulations of the metal. A series of inking rollers then pass over the plate, and the ink is rejected by the water-holding areas and accepted by the greasy image. The inked image is transferred to the rubber blanket and is then offset to the paper travelling around the impression cylinder.

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Universalium. 2010.

Look at other dictionaries:

  • offset printing — off set print ing, n. (Printing) A printing technique in which a lithographic image on an inked metal or stone plate is transferred first to a rubber sheet (usually on a cylinder) before transfer to the paper. Called also {offset lithography}.… …   The Collaborative International Dictionary of English

  • offset printing — n. a printing process in which the inked impression is first made on a rubber covered roller, then transferred to paper …   English World dictionary

  • Offset printing — Web fed offset lithographic press at speed …   Wikipedia

  • offset printing — noun a plate makes an inked impression on a rubber blanketed cylinder, which in turn transfers it to the paper • Syn: ↑offset • Derivationally related forms: ↑offset (for: ↑offset) • Hypernyms: ↑printing, ↑ …   Useful english dictionary

  • offset printing — (lithographic)    Printing from a smooth surface plate that has been treated so that the printing areas are ink attracting and the nonprinting areas are ink repelling. Originally this process used a smooth stone surface, but today most offset… …   Forensic science glossary

  • offset printing — method of printing in which a printing plate first receives ink and then transfers the ink to the paper (rather than applying ink directly to the paper) …   English contemporary dictionary

  • offset printing —    The printing process in which an inked image on a metal or paper plate is transferred to a smooth rubber cylinder and then to the paper. Also see lithography and planography …   Glossary of Art Terms

  • Offset printing — Офсет, офсетная печать; Офсетная печать …   Краткий толковый словарь по полиграфии

  • offset printing — Ira Rubel …   Inventors, Inventions

  • offset printing —    A form of lithography that uses a rubber blanket to accept ink from a plate, and press it onto paper …   IT glossary of terms, acronyms and abbreviations


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