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  1. #1

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    C-41, effect of changing temperature

    I'm thinking of doing some c-41 processing using a Jobo CPP-2 and a 3010 expert tank. Kodak Flexicolor chemistry if I can get it. Mostly 5x4 160Portra VC and 400PortraNC.

    In my reading I see that the developer step is typically 3 1/4 minutes. I'd like a longer processing time (for consistency and to perhaps let me do a 1 stop pull on occasion). Say six minutes or so. The obvious way to do this would be to lower processing temperature to, say, 28C from the normal 38C.

    So what happens if I lower the processing temperature? I don't want to compromise film quality (color shifts, loose shadow detail, that sort of thing). Anyone have any experience an/or insights they'd be willing to share on this topic?

  2. #2
    petras@foto.sk's Avatar
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    Be careful

    Look at this especiallly page 5-29 in Z131-5:
    http://search.kodak.com/?pq-locale=e...obal=en&q=z131.
    Read all 5 books first, then you make experiments.

  3. #3

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    This is color film, not B&W: You'll get color crossover if your temp is more that about 5 degrees F away from 100F, even with a corresponding adjustment of the time (as one would do with B&W film).

    [On the other hand, most all C-41 minilab processors cannot do push processing, i.e. they are limited to exactly 3:15 in the developer; so one is forced to bump up the temp to 104-105F to get puch processing.]

    Quote Originally Posted by Bruce Watson View Post
    I'm thinking of doing some c-41 processing using a Jobo CPP-2 and a 3010 expert tank. Kodak Flexicolor chemistry if I can get it. Mostly 5x4 160Portra VC and 400PortraNC.

    In my reading I see that the developer step is typically 3 1/4 minutes. I'd like a longer processing time (for consistency and to perhaps let me do a 1 stop pull on occasion). Say six minutes or so. The obvious way to do this would be to lower processing temperature to, say, 28C from the normal 38C.

    So what happens if I lower the processing temperature? I don't want to compromise film quality (color shifts, loose shadow detail, that sort of thing). Anyone have any experience an/or insights they'd be willing to share on this topic?

  4. #4
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    As temperature goes down, the bottom layer becomes less developed when the top layer is properly developed. If you properly develop the bottom layer, then the top layer is overdeveloped. The final result can be fog and crossover. Don't do it.

    PE

  5. #5

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    Quote Originally Posted by Photo Engineer View Post
    As temperature goes down, the bottom layer becomes less developed when the top layer is properly developed. If you properly develop the bottom layer, then the top layer is overdeveloped. The final result can be fog and crossover. Don't do it.

    PE
    I was afraid of that. The more I thought about it the more I thought it wasn't going to work.

    Thanks for the explanation.

  6. #6

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    dilution of developer?

    If lowering the temperature won't work, how about increasing dilution of the developer? Let me guess -- it won't diffuse through the layers correctly and give me more or less the same problem?

  7. #7

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    3:15 is fairly simple. What's a one stop pull 2:45? Even that shouldn't be challenging.

  8. #8
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    The push or pull is not the problem it is the temperature and its relationship to reactivity and diffusion. IDK what would happen if you diluted the developer though, but I suspect nothing good.

    The C22 developer had CD3 in it instead of CD4 and used benzy alcohol. It took something like 20 minutes at 75 deg F to work, but the film was designed for it. I ran a lot of film through processes at 75 with C41 films and all I got was scrap.

    PE



 

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