An improved process for the production of negatives from opaque originals for photolithography

  • Inventors:
  • Assignees: Max Ullmann
  • Publication Date: July 07, 1922
  • Publication Number: GB-156692-A

Abstract

156,692. Ullmann, M. Jan. 7, 1920, [Convention date]. Photo-mechanical printing-surfaces; chromogelatin and like processes; films, stripping.- Relates to the production of negatives for making photo-mechanical printing-surfaces in accordance with the method of Specification 24607/13, and consists in producing the negative with the negative film embedded between transparent thin films, one of which allows the negative to be stripped from its support and the other provides a protective coating. The stripped negative being flexible is adaptable for different printing processes. In the production of the negative plates two glass plates may be clamped together and formed with a rubber margin in each outer surface, as well as a coating of rubber on the edges. A wax film is formed on the outer surfaces from a solution of beeswax in carbon tetrachloride, and the plates dipped into a collodion solution containing castor oil. The plates are then separated, and negatives obtained by coating with a thin film of chromated colloid, exposing through the plate in contact with the opaque original, and developing by washing out the unexposed parts. The plate is then coated with a protective coating of gelatin and glycerin, and the film is stripped from the glass support by cutting through along the rubber borders. In the Specification as open to inspection under Sect. 91 (3) (a) the invention was described' without reference to Specification 24607/13.

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