Photo galvanography

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As Fotogalvanografie even Photogalvanographie , (Greek. "Naturgravierung") refers to one of Paul Pretsch in Vienna around 1854 exerted in London invented and later extended by him years method for generating printable sheets of photographs .

Procedure

A glass plate is coated with a mixture of gelatine , potassium dichromate (double chromate) and silver iodide (iodized silver), dried and, depending on whether a copper or letterpress plate is desired, exposed under a photographic negative or a positive .

The glass plate is then washed in heated baths and dilute borax solution until a relief has developed, which is hardened in alcohol and coated with copal lacquer, whereupon the picture is dried in the heat. From the now unchangeable relief a galvanoplastic copy is made in copper, which hardly needs any tutoring with the burin in order to be ready for printing.

Duncan C. Dallas in London practiced photographic galvanography under the name Dallastypie ; Joseph Leipold , director of the banknote printing plant in Lisbon, used it to create excellent photographic reproductions. An extraordinarily fine, worm-shaped grain gives the photographic galvanography images great softness in the lighter tones, and almost the warmth of the copperplate in the dark ones .

historical development

The galvanic molding of plastic objects has been known since 1840. Paul Pretsch worked at the kuk Hof- und Staatsdruckerei ( Print Media Austria ), where he learned the natural self-printing invented by Alois Auer von Welsbach . In 1851 the kuk Staatsdruckerei exhibited its manual and photochemical processes of gravure printing and lithography at the first world exhibition in London . There Pretsch got to know the methods of photographic, photomechanical and galvanoplastic reproduction processes used by Talbot and others. In the same year he moved from Vienna to London and patented the method of photographic galvanography that he had developed in the meantime, the difficulty of which consisted in molding the sensitive gelatin relief and producing a gravure form from it. The result was that the shadows had significantly more depth than the lights. He also founded the Patent Photo-Galvano-Graphic Company and in December 1856 produced the first edition of a photo-mechanically produced portfolio. This and the four following portfolios, each containing four pictures, were the first published works to be produced in a purely photomechanical manner in larger editions. Even William Fox Talbot worked on the photography and the production of photographic printing plates. In 1858 he received a patent for an innovation in the manufacture of gravure printing plates. It is described that an exposed chrome gelatin layer, which does not initially have to swell in water, is etched with a sequence of ferric chloride solutions of decreasing concentration in order to achieve different shades of shade.

literature

  • Wolfgang Autenrieth: New and old techniques of etching and fine printing processes - An alchemistic workshop book for erasers: From 'witch's meal and dragon's blood' to the photopolymer layer. Tips, tricks, instructions and recipes from five centuries , Krauchenwies 2010, 230 pages, ISBN 978-3-00-035619-3 , ( table of contents , (→ excerpts online) )
  • Otto M. Lilien: The gravure. Claus W. Gerhardt: The smaller printing processes (= history of printing processes. Vol. 3 = library of books. Vol. 5). Hiersemann, Stuttgart 1978, ISBN 3-7772-7814-9 .

See also