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  1. #11
    Photo Engineer's Avatar
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    C41 is based on proper diffusion of chemicals into and out of the film at 100F. If you change the temperature, you ruin this process. It involves diffusion in of the developer and out of the DIR fragments and Iodide which control color, grain and sharpness.

    So, almost all C41 films done at room temp seem to suffer from overdeveloped yellow and underdeveloped cyan! And, believe me, I have tried this more than one time. I've even used a water bath after the development step to increase the cyan and "stop" the yellow. It just does not work right.

    C22 was based on slow development with no DIR fragments to control image quality. When DIRs became available, the researchers on that chemistry tried to get the C22 process to work with the new chemistry and emulsions and it just did not work correctly. Something always went wrong. So, they devised C41 and doing so got rid of Benzyl Alcohol and changed from CD3 to CD4 to gain higher activity even at 100F, because they needed this activity due to the DIR fragments which inhibit development.

    Short thumbnail sketch for those interested.

    PE

  2. #12
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    Well what if I used, you know, water spiked with DMSO... I mean if it's just a solubility issue... I know, I know, it's not recommended by the manufacturer, mea culpa...
    "Only dead fish follow the stream"

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  3. #13
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    I've tried DMSO actually, and it did nothing. There are reports of it doing things when making emulsions though. There is this Chinese patent......

    PE

  4. #14
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    Quote Originally Posted by keithwms View Post
    but of course there are also technical reasons why it works so well with monobaths i.e. the way the developer quickly finishes its work and the fixing action starts right away, locally, so you can't really get overdevelopment. But in general there are more problems with uneven dev reported by people who do stand and semi-stand.... just something to think about for those working with really big negs.
    As you said yourself, monobath is a process which works to completion, so it's quite difficult to get unevenness. Semistand gets its unevenness not from long development but from uncontrollable liquid motion in the bath: hot D-8 would yield unevenness from stand development after only a few minutes. What should be a homogeneous diffusion process is in fact dominated by chaotic streams in the dev, so you end up with funny effects.

    I don't know where the uneveness from C41 comes from, like wiffbiffherb I've seen yellow streaks in blue skies. Since I agitate every 15 seconds it's not a stand development kind of problem.
    Quote Originally Posted by Photo Engineer View Post
    C41 is based on proper diffusion of chemicals into and out of the film at 100F. If you change the temperature, you ruin this process. It involves diffusion in of the developer and out of the DIR fragments and Iodide which control color, grain and sharpness.

    So, almost all C41 films done at room temp seem to suffer from overdeveloped yellow and underdeveloped cyan! And, believe me, I have tried this more than one time. I've even used a water bath after the development step to increase the cyan and "stop" the yellow. It just does not work right.
    Tetenal states a range of 30°C to 48°C for their C41 kit. They recommend 38°C if possible, apparently this yields the best results for most. But sometimes processing at a different temperature is more desirable even if this means potential draw backs in image quality.

    The biggest defect from low temp development according to what you write is a color cast which is different in mid tones, shadows and highlights and therefore not correctable by pure analog means. This would, of course, be completely unacceptable in any commercial process, but to me a color cast is more acceptable than the kind of streaks that I have seen and which the thread starter posted.
    Trying to be the best of whatever I am, even if what I am is no good.

  5. #15
    jbl
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    Quote Originally Posted by Photo Engineer View Post
    So, almost all C41 films done at room temp seem to suffer from overdeveloped yellow and underdeveloped cyan! And, believe me, I have tried this more than one time. I've even used a water bath after the development step to increase the cyan and "stop" the yellow. It just does not work right.
    PE, is this because the yellow layer is on top? I'm still trying to wrap my head around this of which layer is first and how the colors in the negative relate to colors in the positive.

    -jbl

  6. #16
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    What I describe is called "crossover" in that the blue image is too high in contrast (Yellow dye) and the red image is too low in contrast (Cyan dye). The top and bottom layers do not develop correctly. This could be corrected in PS, but there is no correction possible in traditional RA printing.

    It can also be corrected in 3 color printing in Dye Transfer and the like by adjusting the separation negatives for contrast.

    PE

  7. #17
    jbl
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    That makes sense, thanks!

    -jbl

  8. #18
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    So... and I know the gods will smite me for saying this but... we could just as well do c41 at room temp if we're going to use unmentionable processes anyway..
    "Only dead fish follow the stream"

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  9. #19
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    Well, you are on your own. IMHO the crossover is so huge that there is going to be a big problem correcting it with lots of trial and error. If it is outside of the scope of adjustments possible, then you will have a problem.

    And, this begs the issue of whether there will be bumps and kinks introduced into the curves due to the response of the 9 components and whether all C41 films will respond the same.

    You see, I gave the simplistic answer above to a very very complex issue.

    PE

  10. #20
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    Quote Originally Posted by keithwms View Post
    So... and I know the gods will smite me for saying this but... we could just as well do c41 at room temp if we're going to use unmentionable processes anyway..
    Since when is contrast masking unmentionable!?

    Actually I have been reading up on it, using real pin registration masks. If I live long enough I'm going to master that.

    Hell, I had to learn Morse code way back when. I may as well add to the pile of arcane skills. You never know what skills might come in handy after TEOTWAWKI. (The End Of The World As We Know It)
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