Can ferricyanide / Dichromate bleach be used in C-41?

Discussion in 'Color: Film, Paper, and Chemistry' started by htmlguru4242, Apr 17, 2006.

  1. htmlguru4242

    htmlguru4242 Member

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    I've recently become interested in home-processing color film, as I've rediscovered that color can actually be nice and useful [sometimes]. However, commercial processing can get expensive. So anyway ...

    The developer seems to be fairly inexprensive; concentrate to make 1 gallon of Flexicolor developer is about $10.00. They don't ship, but I'll probably go down to the city soon, so that's not an issue.

    However, that still leaves the bleach & fix unaccounted for. So my question is this: I have ferricyanide and dichromate bleaches for reversal processes. Can I use either one of these in a color process?

    I know that black and white fixer is a bit different, but it'll work... also, is a stabiliser still needed, and, if so, where can it be purchased?
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    If you do, the process becomes much more complicagted.

    Also, the results cannot be certified as the standard test at EK no longer includes a ferricyanide bleach test, IIRC.

    The process would be similar to this:

    Color develop
    Stop with clear
    Wash
    Bleach
    Wash
    Fix
    Wash
    Stabilize

    The stabilizer, contrary to some opinion is still needed. It contains proprietary ingredients to stabilze the color film.

    PE
     
  3. Nick Zentena

    Nick Zentena Member

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    I'd be carefull using B&W fixer for colour film. I know some might work okay but colour fixer is usually much cheaper then B&W and will do both B&W and colour just fine. So why go to the hassle of figuring out which B&W fixer will work with colour film?
     
  4. htmlguru4242

    htmlguru4242 Member

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    Oh, wow, I didn't realize that; now that I look on B&H, you're definetely right. -- And the color stuff will do B&W film as well?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    I missed the comment about fixer as well in the OP. You CANNOT use any B&W fixer for color film due to the pH being either too low or too high. The pH for color fixers must be between about 6.3 and 6.8 max range.

    Color fixer can be used for B&W film.

    PE
     
  6. Jordan

    Jordan Member

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    PE and/or Nick, can a batch of C-41 fixer that has previously been used for C-41 film be safely used with B&W film?
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Yes it can, but the individual fix time for your film should be determined beforehand by the old 2x the time it takes to clear.

    PE
     
  8. edz

    edz Member

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    As an additional note.. Ferricyanide can't be mixed with Fix for a blix as it falls apart. All modern bleaches are based around Ferric ammonium EDTA and mix well and remain stable so not only can one reduce things to a single fix but one can reduce things to a single bleach (which can be used in E-6 as well) and mix as one needs bleach or blix.
     
  9. Photo Engineer

    Photo Engineer Subscriber

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    Ed, by the time you make the film blix strong enough to bleach and fix all of the silver in color film, particularly when the silver is loaded with iodide and DIR fragments which are bleach and fix inhibitors, the blix becomes unstable, and that is why I suggest not using a blix for film.

    They are unreliable and unstable if they are strong enough to do the job required of them.

    There are ways around this and my co-workers and I hold a patent on it, but it does not come easy, to make a film blix that removes all of the silver to the exacting standards required for good color.

    BTW, a good Ferricyanide / hypo blix is possible, but it is a throw away, single use solution. You mix, use and discard. They can be designed. There are many others using off-the-shelf chemistry and some with rather exotic chemistry that will blix.

    PE
     
  10. htmlguru4242

    htmlguru4242 Member

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    Good to know about the color fixer being useable for B&W, much easier.

    So it's been established that ferricyanide bleaches are OK, but my dichromate question is still unanswered; how about those?
     
  11. Photo Engineer

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    Ummm, someone else may have said this, but I don't think I said a ferricyanide bleach was ok. I said it was no longer used at EK for testing films, so I didn't know if it was acceptable.

    Dichromate is similar to ferricyanide. It was once used as a color film bleach and is no longer tested with color films at EK. So, if the films are untested, the bleach may work, but you are on your own regarding dye stability, dye destruction or hue changes. Even the formation of a dye-metal complex can cause problems.

    PE