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  1. #21

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    Go back far enough in time to maybe the 70s or 60s and as I recall things the equivalent of C41 processing was done at much lower temps.

    So was lower temp developing always a second best solution or was it simply that an improved process called C41 demanded 100F?

    Even if you could buy stuff for the older low temp process today would the negs eventually suffer compared modern C41 negs processed at 100F?

    Sounds as if we might need PE to chime in here as he must be one of the few with enough experience and grey hairs to comment on it meaningfully

    pentaxuser

  2. #22
    RPC
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    I don't know if a high or low temperature process matters per se as as far as quality goes, but I would guess the high temp we use for C-41 was chosen to help labs process faster as color became more popular, not because of any better quality. My gut feeling is that a lower temp process would always be easier to design, and have more headroom and thus less chance for error but by the same token would probably always take longer to process.

    RPC

  3. #23

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    Maybe the higher temperature opens the color layers to let the chemistry in?

    I have seen where people use cold C-41 to get fair color from ancient C-22 film.

    But even out on the prairie, with a wagon train, one should be able to rustle up some hot water to get those C-41 chems up to 102*f. Cook those negatives alongside a pot of beans.
    Last edited by wblynch; 07-13-2011 at 12:11 AM. Click to view previous post history.
    - Bill Lynch

  4. #24
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    Color negatives produced for the C-41proces will surely give the best photographic results at the temperature recommended. Working at half the recommended temperature, even with time compensation I think it will generate a bad color balans. Sensitometrice curves cross. See that on a gray scale. Using a 18% gray than you may be wrong. The gri can be corrected, but what happens with lighter or darker grays do not see. I use for photo color negatives - ECN 2 process. ECN 2 is for motion picture film. I use it for about 25 years. It is at hand and know well.
    George

  5. #25
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    C41 films from Kodak and Fuji rely on the use of DIR couplers. These couplers release chemicals that inhibit development around the development site and also diffuse to adjacent layers (along with released Iodide) to correct color rendition by inhibition. All of this chemistry including release and diffusion, is adjusted to work best at 100F in the authentic C41 developer. Therefore, you can degrade color, sharpness and grain by using the wrong process.

    It may not happen. I have thought of several chemistry combinations to compensate for a low temperature, but testing this is hard and expensive if it is to be done right.

    So, this is quite esoteric chemistry that you are tampering with. I am just surprised to see it work out so well. But, we have no comparisons, nor do we have data on grain and sharpness.

    PE

  6. #26

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    An old-time lab technician told me, some years ago, that the change of processing to 100F was much appreciated at the time C-41 was introduced , as this is always above normal room temperature. So all that was needed was a thermostatically controlled heating of the tanks, whereas before a solution temperature of 68F could need both heating and cooling in variable climates. Never seen any other specific references to this, but it seems logical?

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