Is sodium dichromate light sensitive?

Discussion in 'Alternative Processes' started by htmlguru4242, Feb 13, 2006.

  1. htmlguru4242

    htmlguru4242 Member

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    I've been reading about alternative processes involving dichromates, and I realize that I have large amounts of sodium dicrhomate (in the form of tray cleaner) sitting in my developer shelf. The, maybe, 1/16th of a bottle that I used for making up reversal bleach is still going after processing a 4x5 sheet, a 120 roll and 2 135 rolls of film, so I'm thinking this is going to last FOREVER.

    So, my question is, can this sodium dichromate be used in alternative processes as a light sensitive agent (I know it would have to be isolated from the other chemistry in the solution, but that's another issue).

    Does anyone know?
     
  2. donbga

    donbga Member

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    Sodium dichromate can be used as a light sensitive agent. What is the percent solution that you have? If it is a weak solution then you may not be able to get very good results.

    >
    (I know it would have to be isolated from the other chemistry in the solution, but that's another issue).
    >

    I'm quite confused by this comment though.

    Don Bryant
     
  3. htmlguru4242

    htmlguru4242 Member

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    Ah, the sodium dichromate I have is part of the Kodak Tray Cleaner, which consists of sodium dichromate and sulphiric acid in an aqueous solution. (It is designed for cleaning trays in automatic processors, though I use it for reversal processing as a bleach). What I'm saying is that I'm not sure how the Sulphuric acid will affect the dichromate in the solution; the bleach is quite acidic so I don't know what would happen if it's mixed with, say, gum of casein for one of the alternative processies.
     
  4. donbga

    donbga Member

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    That's what I thought you menat. Don't used tray cleaner for gum or casein printing. Ammonium or potassium dichromate is fairly cheap (though not equivalent in gum printing), so just purchase some of that and save the tray cleaner for trays.

    Don Bryant
     
  5. htmlguru4242

    htmlguru4242 Member

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    Probably a good point, Don, however, the point was to use what I have; I have NO space for anything extra. I might as well try using what I have - can ammonium / potassium dichromate be shipped in the US? B&H won't do it ...
     
  6. Keith Taylor

    Keith Taylor Member

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    Yes, but it's classified as a hazardous material and so it has to be sent ground. If you buy it from the Formulary they'll also ask that you fill out a DEA form before an order is shipped. I get my Potassium Dichromate from Bostick and Sullivan, $53/1000grams.
    Keith.
     
  7. Kerik

    Kerik Member

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    In my experience, sodium dichromate does not behave very well for gum printing (but I did not test it extensively). I primarily use ammonium dichromate because it seems to have a longer scale (lower contrast) than potassium dichromate. Gum printing is inherently a fairly short scale process, so I usually prefer the longer scale of ammonium. I use potassium on later dark coats when I just want to kick the shadows a little darker.
     
  8. donbga

    donbga Member

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    Using tray cleaner for gum or caesin printing will just waste your time and materials. I can't beleive you can't find room for 100 grams of ammonium dichromate.

    Don
     
  9. DarkroomDan

    DarkroomDan Subscriber

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    Kerik:

    Really like your new collodion print on your site's openning page. Very nice.

    Dan