GB426849A - Improvements in or relating to planographic printing - Google Patents

Abstract

426,849. Printing-surfaces damping- apparatus. BROOKES, N. E., 1, Quality Court, Chancery Lane, London.-(Multigraph Co. ; 1814, East 40th Street, Cleveland, Ohio, U.S.A.) June 8, 1934, No. 17048. [Class 100 (ii)] The non-printing area of a metal printing- plate is rendered glycerine-receptive and is given a thin coating of glycerine, printing being effected with an ordinary greasy ink; alternatively, other materials such as tough parchment paper which are retentive of a greasy image and are or can be rendered glycerine-receptive may be used in place of metal. A metal plate may be rendered glycerine-receptive before or after the application of the image by treatment with a solution of salts, preferably ammonium nitrate and ammonium dihydrogen phosphate. The image may be formed directly on or etched into the surface or formed photographically on a colloid film. The ink is preferably slightly acidic, unless the surface is completely coated with a colloid film. If many imprints have to be taken from the surface, additional glycerine is applied periodically, preferably by means of a foraminous roller, e.g. of felt or sponge rubber, to which glycerine may be applied by a saturated hand roller. An auxiliary roller is preferably also used, formed of a material, e.g. vulcanized rubber or artificial resin, which is not readily wet by glycerine or affected by the salt solution. To prevent ink being picked up by the glycerinecoated surface, a small amount of a solution of ammonium nitrate and ammonium dihydrogen phosphate may be added to the glycerine, or a solution of these salts may be occasionally applied to the glycerine film. Equivalents such as glycol and triethanolamine may be used in place of glycerine.