Bromine oil pressure
Bromoil even Bromölumdruck is as precious printing process no pressure process in the strict sense, but a photographic positive copying processes . It was invented by Welborne Piper in 1902 and was widely used from 1907.
The basis is a positive silver bromide that was exposed on unhardened and therefore swellable silver bromide paper . After fixing and soaking, the silver image is bleached with a chromate bleaching bath, which consists of a solution of copper sulfate , potassium bromide and potassium dichromate or ammonium dichromate solution .
This chemical process causes partial hardening ( tanning ) of the gelatin layer of the paper, which makes it water-insoluble. This tanning is proportional to the existing silver image. This gelatin relief is watered to apply a color. The non-hardened areas (light picture tones) absorb a lot, hardened areas correspondingly less water. The water is removed from the surface of the paper and an oily printing ink is then dabbed on with various types of brushes or rollers . This only sticks to the hardened and therefore water-free areas. This creates a positive dye image. The color tone is determined by the choice of oil paint. A bromine oil transfer is created by transfer printing on paper. This procedure can be carried out several times and images of independent charm are created.
This process was also used to produce color photographs with very natural coloring before the invention of color film: By color separation with filters (blue, green, red), 3 precisely fitting black and white photos of a motif were produced and the gelatin matrices with yellow on top of the blue -, colored red on the green and blue on the red filter holder and then printed on top of each other in multiple printing processes.
See also
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) )
- Josef Maria Eder : The pigment process, oil, bromine oil and rubber printing, blueprint and dusting processes with chromates, pinatypia, kodachrome, hydrotypes, copying processes with color-giving organic compounds, diazotype processes, images with tanning and chromogenic developers and artificial resins (= detailed manual of the Photography. Vol. 4, Part 2). 4th, completely revised and enlarged edition. Knapp, Halle (Saale) 1926 (reprint. Lindemann, Stuttgart 1990, ISBN 3-928126-09-1 ).
- Gene Laughter: Bromoil 101. A Plain English Working Manual and User's Guide for beginners in the Bromoil Process. 5th edition. Self-published 1999, (Contains a Bromoil bibliography).
- Emil Mayer : Bromöldruck und -Umdruck (= Encyclopedia of Photography and Cinematography. Issue 81). 10th and 11th supplemented edition. Knapp, Halle (Saale) 1927, digitized .
- Albert Mebes: The bromine oil pressure. Detailed manual for single and multi-color bromine oil printing, as well as for transfer printing on paper, metal and stone. Union, Berlin 1914.
- Luis Nadeau: History and Practice of Oil and Bromo Oil Printing. Lindemanns, Stuttgart 1992, ISBN 3-928126-26-1 .
- Jörg Pfäffinger: The bromine oil pressure. A guide for practice. Lindemanns, Stuttgart 2003, ISBN 3-89506-240-5 .
- The Art of Bromoil Centenary 2007. The Bromoil Circle of Great Britain, Malvern 2007, ISBN 978-0-9557199-0-5 .
- Viennese types. = Viennese types. Photographs C. 1910 by Dr. Emil Mayer (1871-1938). Essay by Edward Rosser. With a foreword by Rudolf Arnheim . Blind River Editions, New York NY 1999, ISBN 0-9672975-0-8 .