Ilford Colour Transparency Films


Before WW2 Ilford Limited was mainly a manufacturer of sensitised materials. They had a brief encounter with Dufaycolor but once the war started government directives prevented any further research into colour techniques. By contrast Kodak in the USA had forged ahead and produced their Kodachrome colour transparency film and by 1942 had also produced Kodacolor negative film and was marketing and offering a processing service for these materials. These materials were at the time, during WW2, only available in the USA.

After the war in 1945 Ilford Limited lost no time and a small team started to research colour processes. Despite having access to FIAT - CIOS and BIOS reports, the possibility of using a similar process to Agfacolor was dismissed because of the difficulties in producing the colour couplers that this system needed. But by 1948 the team had produced a non-substantive colour transparency film called Ilford Colour D. The "D" stands for daylight; other light sources would need filters to get the correct colour balance.  They got around patent issues that clashed with Kodachrome by the inclusion of a silver sulphide barrier layer and a colloidal silver barier layer. Ilford Colour D had a speed of 8 ASA like Kodachrome.

The new Ilford Colour Film D was advertised in living black and white in the BPA 1949. Later Ilford marketed a type A for exposure with photoflood lighting and a Type F for use with clear flash bulbs. This is before the flashbulb manufacturers decided to market blue coated flashbulbs that could be used with daylight balanced films.

Attention was then turned to producing a material to print the transparencies. In 1947 Silver Dye Bleach materials made by Dr Bella Gaspar from the USA were tried but these failed to produce satisfactory prints. However an Ilford team using dyes supplied by Geigy of Switzerland did manage to produce a material that could make colour prints of the required quality by 1949. This was the first time that commercially produced prints were made of a satisfactory standard in one step. The base for this new material was white plastic rather than paper; the finished prints were of a high gloss that did not use conventional glazing techniques and only required air-drying. Something like modern resin coated photographic papers. The base was manufactured by Bexford Limited a company jointly owned by Ilford Limited and British Xylonite/Bakelite Xylonite Limited.

Click here for more about Ilford Colour Film Type D.