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  1. #1
    kept's Avatar
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    Avoiding potassium dichromate in bromoil process

    Hello, everyone! I'm new to this forum and new to the bromoil process.
    I wanted to ask are there any possibilities of avoiding potassium dichromate in the bleaching solution preparation? Maybe there are some alternative recipes for this solution? Because it's difficult to obtain it in Lithuania because of its toxicity.

    Cheers!
    Last edited by kept; 08-07-2012 at 06:16 AM. Click to view previous post history.

  2. #2
    gandolfi's Avatar
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    not to my knowlegde. The potassiumdichromate acts as a tanning agent. Without, no hardening of the gelatine, and therefore you can't ink it. (it will all be black...)

  3. #3
    holmburgers's Avatar
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    Well couldn't you in theory use a tanning developer, a la Kodak's dye-transfer developer? Assuming you've exposed an image onto a "bromide" paper, developing this in a pyro developer with high tanning properties would give you something analogous to a dichromate-bleached print.

    And although this would only work with oil (not bromoil, that is), you could make a diazo sensitized gelatin paper, expose and wash/clear. This would also give you a gelatin image composed of both tanned and untanned gelatin.

    So, there's some food for thought.
    If you are the big tree, we are the small axe

  4. #4
    MDR
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    Ever since I read about the chiba system I keep thinking that a bleach with Ammonium Ferric citrate and Hydrogene Peroxide should work for Bromoils. But I am not actually sure that it does maybe one our resident chemists can help.

    Dominik

  5. #5
    artonpaper's Avatar
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    I can't answer your question, but when it comes to shipping dichromates, here in the US, at least, the powder form requires HAZMAT shipping which is very expensive. I order dichromate from Bostick and Sullivan and I ask them to dilute it to the solution strength I need. For some reason, the dichromate in liquid form doesn't require HAZMAT shipping. Perhaps you can find a supplier who can work with you in that way.

  6. #6
    Klainmeister's Avatar
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    Try reading the conversation that ensues after this post: http://thecarbonworks.com/blog/?p=1113

    Gives ya an idea regarding dichromate.
    K.S. Klain

  7. #7
    holmburgers's Avatar
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    Quote Originally Posted by Klainmeister View Post
    Try reading the conversation that ensues after this post: http://thecarbonworks.com/blog/?p=1113

    Gives ya an idea regarding dichromate.
    Wow, that's definitely the best, most concise account of dichromate dangers, history and disposal I've seen all in one place. Thanks for posting.
    If you are the big tree, we are the small axe

  8. #8
    Klainmeister's Avatar
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    What's funny about that situation is that we had been working on those oil prints for a while and everytime someone new came by or someone outside heard of the use of dichromate, there was an instant reaction about the dangers involved...yada yada. It seems to never end. Recently playing with a revised formulation of cyanotype we tossed it in a tray of dichromate instead of hydrogen peroxide since none was available. Worked like a charm. Not worried one bit.
    K.S. Klain

  9. #9
    kept's Avatar
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    Thank you all very much for the answers!
    It's funny though I've found an old glass vessel almost full of potassium dichromate (according to the formula written on it) in an old photo lab. It's a bit strange it is a white powder not red, as I saw it in Wikipedia. Is it still good to use? Does potassium dichromate have an expiry date?

  10. #10
    holmburgers's Avatar
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    Hmmm... I think it's probably not potassium dichraomte then. It's an INTENSE, unmistakable orange, and I don't think it would turn white with time (??)

    And if it is potassium dichromate, I wouldn't want to use it in that state anyways. Always best to avoid messing with "mystery chemicals".
    If you are the big tree, we are the small axe

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