An Improvement in Process Work for Producing Etched Plates and other like Objects for Printing and other like Process Work.

摘要

17,480. Bain, R., and Bain, R. D. Aug. 20. Photo-mechanical printing.-In producing intaglio or relief printing-surfaces, the grain in the etching- resist is formed by the use of a vegetable gum containing essentially a bassorine element in a chromated fish-glue emulsion. The original is photographed without the use of a screen or the like, and the negative or positive, as the case may be, is printed direct upon the prepared plate which is etched after exposure without development .or further treatment except backing or lining. The sensitive emulsion contains gum arabic oxidized with chrome alum 20 -parts, fish glue 20 parts, a vegetable gum containing bassorine 20 parts, and bichromate of ammonia neutralized with bicarbonate of ammonia 40 parts. The temperature of the mixture during preparation should be 40-60‹ C.