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Agfa-Farbenplatte The Agfa colour plate (Farbenplatte) was the German equivalent of the French Autochrome plate.

Pre-production development 1908-1916

Traditionally a dye manufacturing company Agfa had moved into photographic products, starting in 1887 with a range of photographic developers; in 1893, a range of 'Isolar' black and white dry plates; in 1898, a range of celluloid-based photographic films; in 1899, movie film, and around 1908, they decided to move into colour photography .

The Lumière brothers had launched their Autochrome colour glass plates in June 1907, and by this time (1908), their factory at Montplaisir near Lyon, was producing some 6,000 plates per day. The Autochrome was a patented Additive colour process, which used grains of potato starch, dyed in the three primary colours, to form the colour screen (or reseau).

Rejecting the idea of ruled colour screens of the like used by Joly, McDonough and Krayn, the first process they seriously considered was the short-lived Veracolor process which was launched in 1909. Developed by Polish inventor Jan Szczepanik (June 13, 1872 – April 18, 1926) and German Dr Karl Hollborn of Leipzig, it used a colour screen made of powdered gelatine, dyed in the three primary colours, which was then dusted over a moist collodion plate; the results were however unsatisfactory .

AGFA based the Farbenplatte upon the work of Jens Herman Christensen (19 September 1877 - 1953) of Holte, Denmark, (working for Burmeister and Wain's Eksport Kompagni). On 1 April 1908 he had been granted German patent number DRP 224465 for a "Process for the production of multi-colour screens by applying particles dyed in the basic colours and emulsified in a liquid to the screen support". The text of the patent did not specify specific materials to be used, but suggested dyed shellac emulsified in turpentine oil. In January 1909, Burmeister and Wain offered Agfa the patent, but they declined.

In June 1910, Christensen travelled to Berlin to demonstrate an improved process, the results impressed them, and in November of that year Agfa purchased the patent rights (with the exception of England and the United States). In the following couple years Christensen worked with Agfa to develop the process for production. In 1912, the first samples were shown, and they not only confirmed a quality similar to that of the Autochrome plate, but also highlighted advantages such as "vividness of colours, translucency of the colour screen and correct colour rendering". The nature of the process produced good translucency since all the droplets in the colour screen were in direct contact with each other (unlike the Autochrome process) so there was no need to add opaque fillers that cut down on light transmission. The plates did not however go into production because of fluctuating colour screen parameters.

Microscopic comparison of Agfa-Farbenplatte and Lumière Autochrome colour screens

The war hindered development due to lack of petrol and turpentine oil. By 1915, Burmeister and Wain were able to supply Agfa with petrol directly from Denmark; Christensen himself coming to Berlin to check the suitability of the petrol for production.

Production development 1916-1918

Dr August Tanzen took over the management of the raster operation in 1915, and was in October 1915, able to report that the production technology had progressed to the point that one hundred and twenty 9x12 cm plates could be produced each week

The Agfa-Farbenplatte finally came to the market in January 1916. The plates were manufactured at their Berlin-Treptow site, and that year they sold 5,390 packs of 9 x 12 cm and 13 x 18 cm plates; the retail price for a box of four 9 x 12 cm plates was Mk 5, and Mk 11 for a box of four 13x18cm plates.

Production development 1918-1936

Production difficulties remained however; there were not only further problems of material supplies during, and after the war, there were also problems with manufacturing the plates. Like the Autochrome, the Agfa colour screen was very susceptible to moisture which could cause the coloured dyes to bleed into each other. In 1920, Christensen began work on a new formula that would be more resistant to moisture. He found that by replacing dextrin with tannic acid, the screens were water-insoluble after drying. Christensen was grated German patent DRP 403590 on 2 June 1923, for a "Process for the production of water-insoluble multicolour screens". The new formula was successful and production increased, and by 1924 it was six times that produced in 1921.

Agfa-Farbenplatten Box 1933

Dr Kurt von Holleben, a newly graduated PhD student, joined Agfa in 1925, and by 1926 he had been appointed head of the colour screen research group, overseeing development and production of Agfa-Farbenplatte plates. Following problems with the colour rendering of both green and blue, he changed the production to use alternative dyes and recommended using a Rapid Filter Yellow filter instead of a Tartrazine Yellow filter to improve blue rendition. He also began work on the lightfastness of the colour screen, work which Christensen continued and in 1927 he demonstrated a new formulation, which involved a switch from basic dyes to acidic dyes. On 8 September 1927, Christensen was granted German patent DRP 469578 titled "Dyed particles for the production of screens for colour photography". The new formula was in production by the end of 1928, but in a letter to Agfa dated 30 April 1929, whilst acknowledging the improvements made, he still recognised that "yellow and blue leaves something to be desired". Further tweaks to the formula were made to correct colour rendition in 1930.

Agfa-Farbenplatte viewed without illumination

The Alte Nahebrücke at Bad Kreuznach August 1933 by Dr Kurt von Holleben

The plates were being sold in England from 1923, and by 1930 Agfa was also selling plates to the USA via the Agfa-Ansco Corporation. The Ansco Corportaion had a long history of supplying photographic equipment in America, dating back to manufacture of daguerreotype plates in the 1850's. The company merged with Agfa in 1928 to create the Agfa-Ansco Corporation.

Also at this time, the decision was made to move production from Berlin-Treptow to Bitterfeld-Wolfen. In September 1930, Dr von Holleben travelled to Wolfen to find a suitable building to house the production equipment. The move was not straightforward as it had to be organised in such a way as to avoid disrupting supplies to customers. By August 1932 a plan had been decided upon, which included (as an interim solution), special equipment for transporting semi-finished products from Berlin to Wolfen. The move began in October with the move of the varnishing machine, drying cabinets and the three screen machines, and continued through November. Colour screen production finally ceased at the Berlin-Treptow site on 6 December 1932.

The senior staff moved from Berlin to Wolfen, and in the beginning of 1933 Dr von Holleben took over the management of the raster plate and film factory there.

In Wolfen development continued on improving the colour screen sensitivity and shrinking the grain size to allow the development of the next generation of products. Released in 1932 under the name Agfacolor, it was an additive colour film on a nitrocellulose film base producing a positive image. In 1934, they released Agfacolor Ultra a faster film version of its predecessor, also on a nitrocellulose film base, which was later changed to a safer acetylcellulose film base.

In 1936 colour screens were made redundant when Agfa developed the ground breaking Agfacolor Nue process. This was a multi-layer colour reversal film with the colour couplers incorporated into three separate emulsion layers coated onto a single 'support' that could be processed in a single colour developer (it was a rival to the Kodachrome reversal film released in 1935) .