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  1. #1
    mikepry's Avatar
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    Fine crystals on palladium prints

    Well the darkroom demons have come back again this month. After mixing fresh potassium oxalate I am noticing really small and fine sparkly crystals on my dried prints. If we were back in the 70's it wouldn't be a problem but now it is! The new PO is the only "new" thing in my process. It is at 33%. I recall seeing this posted before and for the life of me I can't find the thread after numerous attemps. Could someone enlighten me as to what could be causing this? BTW my 15 yr old daughter was looking at my latest prints and she remarked....."Cool, these sparkle in the light." Thanks in advance.
    "EVERY film and paper is good .......... for something"
    Phil Davis

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    Hi Mike...don't know if this is the thread you were looking for, but it might help. That's about as much help as I could be with this, hopefully the guys that know will post something. Please, do post what you find as the reason.
    Mike C

    Rambles

  3. #3

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    Mike,

    33% is close to saturation, but that should not really be an issue because the prints must go through all the clearing and washing steps after that, and PO is fairly readily soluble. The problem with being that high is that you will get crystals in the solution, especially if you use it warm or hot. This can cause damage to the print surface as you pour it over the print, etc.

    I've never had crystalization problems on my prints, so I don't know where to start to solve the problem, but you may want to look at the steps nearest to the end; the wash and the clearing steps. Are you positive you washed long enough? What clearing baths did you use? If you put the print back in water, does the crystals clear, or do they remain?

    Most everyting that we use is fairly soluble in H2O, so my initial thinking is that you may be able to salvage the prints by washing longer. If I had to guess, I would also go with not enough washing after the clearing bath is resulting in some remaining clearing bath chemicals in the paper at the most likely candidate.


    ---Michael
    www.mutmansky.com
    B&W photography in Silver, Palladium, and gum bichromate.

  4. #4
    EricNeilsen's Avatar
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    Quote Originally Posted by mikepry
    Well the darkroom demons have come back again this month. After mixing fresh potassium oxalate I am noticing really small and fine sparkly crystals on my dried prints. If we were back in the 70's it wouldn't be a problem but now it is! The new PO is the only "new" thing in my process. It is at 33%. I recall seeing this posted before and for the life of me I can't find the thread after numerous attemps. Could someone enlighten me as to what could be causing this? BTW my 15 yr old daughter was looking at my latest prints and she remarked....."Cool, these sparkle in the light." Thanks in advance.
    Mike, Are you making your own or mixing from powder? Where did yo buy your powder? What clearing baths do you use?

    Eric

  5. #5
    Ole
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    Just a quick thought: Is your tap water hard, and do you use tap water at any stage in the process? Those small crystals could be calcium oxalate, which will be very difficult to wash off!
    -- Ole Tjugen, Luddite Elitist
    Norway

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    Ole,

    By what mechanism does the calicum in hard water react and produce calcium oxalate?

    I'm on hard (but not really hard) water, and haven't noticed any crystalization with PO, but maybe the calcium is in low enough concentration to not cause the problem.


    ---Michael
    www.mutmansky.com
    B&W photography in Silver, Palladium, and gum bichromate.

  7. #7
    Ole
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    Any calcium in the water will form calcium oxalate. Calcium oxalate is insoluble, and will sho up as small white crystals. Incidentally, that's what kidney stones are made of.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #8

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    Ole,

    Does it strip off the potassium, or does it need free oxalic acid to form?

    Do you know if any of the clearing bath solutions are better at removing this if it forms?


    ---Michael
    www.mutmansky.com
    B&W photography in Silver, Palladium, and gum bichromate.

  9. #9
    Ole
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    Michael -

    potassium oxalate in solution consists of potassium ions and oxalate ions. The oxalate will combine with any calcium ions to form insoluble calcium oxalate monohydrate.

    There's no "stripping" going on - that's already done when you make the solution.

    You won't manage to dissolve it, the only cure is prevention: Add a little potassium oxalate to the water, let stand for a day, then filter before use. Or use distilled / deionised water.
    -- Ole Tjugen, Luddite Elitist
    Norway

  10. #10

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    biological analogy

    Hi,

    I'm a kidney stone expert (not on the MD side, incidently). According to my urologist, oxalic acid is required to precipitate the most common kidney stone... calcium oxalate. Without the oxalic acid the doctor claims the calcium passes freely in the "wash". That's why one of the standard preventative treatments is avoidance of oxalic-bearing food, like spinach and other healthy leafy green veg, cola drinks, coffee, etc. and plenty of water/beer. I know that there is also a chemical preventative treatment but I can't remember what it was. Once the Doc prescribed this (two large horse pills per day) but I stopped taking them -- they passed whole and it was weirding me out! Allegedly whatever chem this was would bind with the calcium and take it out of the system.

    I hope there is a chemist in the house that can continue to help chemically explain your phenomenon. But, it does kinda' sound cool... if the sparkles are in the right place.

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