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Thread: Kodacolor.

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    Kodacolor.

    To anyone with knowledge of tri-pack colour films.
    I am a photographer researching into early tri-pack colour processes, mainly negative-positive processs, such as Gevacolor, Pakolor and others.
    "How did Eastman Kodak process the second type of Kodacolor film, which was marketed between 1944-49?"
    The film had a black and white blue sensitive emulsion layer between the yellow filter layer and the green sensitive (magenta dye forming) layer.
    My theory is: The film was processed in C-22 chemicals to form dye images in the three dye forming layers. Then the film was exposed to white light, through the base, printing the cyan dye layer and the magenta dye layer onto the blue sensitive B/W layer. The film was then processed again in a soft working B/W developer (possibly D-165) to form a weak positive mask image. When the Kodacolor negative was printed onto Kodacolor Paper through the base of the film, the mask would have held back some of the light in the shadow areas of the negative thus lowering the contrast.

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    The C-22 process did not exist at that time, but the one used was a close approximation to it.

    The original chromogenic Kodacolor film had no mask whatsoever, and relied on any 'mask' being formed by using either interimage effects, or a wash after the color developer to promote formation of a positive 'fog' image. Some unmasked color negative films used this method into the 60s.

    The silver mask in Kodacolor, when introduced, was formed much as you say, but none of my texts or records show what kind of developer was used.

    PE

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    To Photo Engineer. Many thanks for info on Kodacolor. J. Coote states in his book "The Illustarted history of Colour Photography" C-22 was used for Kodacolor film since 1942 (p-158). If this is incorrect it would be interesting to know how the earlier process differed from the later named C-22. I remember processing Agfacolor CN17 film back in 1969 with a 15 min. wash after the intermediate bath.I can't imagine the mask in Kodacolor would have made much difference in colour correction, although some references state it was to correct for the unwanted blue absorbtion of the cyan and magenta dyes of the kodacolor negative.D-165 was a soft working developer of that time, but I don't know what developer Kodak actually used.

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    The C-22 and P122 processes for film and paper were developed after the consent decree. The changes to the process were mainly in simplification so that the average darkroom enthusiast or photofinisher could use it without harm.

    Two changes I remember were going to a less toxic color developer (CD3) which required the addition of benzyl alcohol to the developer, and the use of ferricyanide bleach instead of the original quinone / sulfuric acid bleach.

    These are the two that I remember, but I'm sure there were others.

    Since the processing of Kodacolor film was not done outside of Kodak labs, how would anyone really have the authority to state what was used. This was all held behind a 'silver curtain' at EK and not known to the general public.

    The wash in CN17 film caused extra edge and interimage efffects. Konishiroku also used a similar method at that time with their color negative film. I have processed both films and at one time had the processing formulas. A wash after development introduced a mild 'mask' to the negative image as positive fog came up during the wash. This weak positive silver/dye image became a weak mask. The film was designed specifically to take advantage of this, and I have made many fine prints from these color negative products.

    There were many tricks that could be played with this sort of process sequence. I have tried many of them with quite interesting results.

    PE

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    Many thanks for info on mask effect on CN17 film.Strangely enough, this mask effect is'nt mentioned in any of Berger's Agfacolor books, published 1950-67. But there is a mention of a colour correction positive masking process for Agfacolor motion picture film in FIAT report 976. Jack Coote worked for Ilford for many years. He may have just assumed that C-22 and P-122 were used from the start,(1942).on the other hand he must have had contacts in Kodak Ltd in UK and have had some knowledge of Kodacolor.Certainly by 1949 EK were marketing the "Ektacolor Processing Kit" for Ektacolor Type B film,and later, Ektacolor Print Film. Do you know if this processing kit was identical to the C-22 process, or were the solutions, times, temperatures different?
    I beleive CD3 replaced CD2 around 1955, the same time that Kodak Color Print Material Type C was introduced which later became Ektacolor paper. MDT

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    All I know is that there was a different (quinone) bleach and different developing agents. There were a series of process changes over the years, but the major changes took place at the time of the consent decree.

    Until the early 60s, all color negative films but those made by Kodak used the Agfa method of interposing a wash after development to achieve some degree of edge and interimage effects. I still have one of the old kits around here I think. I have lots of negatives processed that way and still have some of the formulas here somewhere.

    PE



 

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