For those using Potassium Oxalate

Discussion in 'Alternative Processes' started by padraigm, Aug 7, 2013.

  1. padraigm

    padraigm Member

    Messages:
    98
    Joined:
    Feb 18, 2010
    Shooter:
    Medium Format
    Hi All,

    As the tile infers I am using potassium oxalate and want to get some feedback on other users experience. I am pleased with the developers performance, however I get large deposits of precipitate/crystals in my solution. I find I am loosing a lot of solution but that probably is more to do with not letting the papers drain enough. But the crystals are a problem as they just get bigger and bigger. Yesterday I heated up the left over solution with some added fresh stuff to a high temperature to put back in the bottle to get the crystals back in suspension. I then but it back on the heating element and proceeded to use it to develop after it was all in solution and at ~90C. Using it to develop was initially good and as expected, but within 20 seconds as the developer began to cool, it became a slushy mess. I thought it had ruined the print but it all seemed to wash off OK. Are others having this issues? Is this normal and if so what is your replenish method? I have just been topping up the bottle from B&S, but as I said the crystals at the bottom are building up significantly.

    Thanks
     
  2. DennyS

    DennyS Member

    Messages:
    12
    Joined:
    Feb 24, 2011
    Shooter:
    35mm
    Sounds like it's a problem caused by evaporation. You should be able to just add a little water back to get it into solution. I routinely replenish with about 1 ml of fresh solution for each square inch of image, no problems.
    Denny
     
  3. TheFlyingCamera

    TheFlyingCamera Membership Council Council

    Messages:
    9,444
    Joined:
    May 24, 2005
    Location:
    Washington DC
    Shooter:
    Multi Format
    I've never had problems with crystals forming in my developer. What kind of water are you using to mix your PotOx? Tap water? I'm wondering if there is some impurity in your water that is causing the developer to crystalize out so fast. Try mixing a fresh bottle with distilled water and see if that solves your problem.
     
  4. deisenlord

    deisenlord Member

    Messages:
    482
    Joined:
    Dec 22, 2004
    Location:
    Minneapolis,
    Shooter:
    4x5 Format
    I use my developer very hot ~160 and this is a common problem due to evaporation. Potox is around saturation when mixed so it doesn't take much evaporation to cause crystals. Just add some water.
     
  5. Vaughn

    Vaughn Subscriber

    Messages:
    5,305
    Joined:
    Dec 13, 2006
    Location:
    Humboldt Co.
    Shooter:
    8x10 Format
    Agree with the Lord of Deisen! (tho I use it at about 100 to 110F).

    I add distilled water occasionally.
     
  6. Ian Leake

    Ian Leake Subscriber

    Messages:
    1,423
    Joined:
    Mar 25, 2005
    Location:
    Switzerland
    Shooter:
    8x10 Format
    I work with a 25% wbv potassium Oxalate solution, and develop at about 65C. Crystals form in the bottom of my storage bottles when it cools overnight, but not during print processing. The temperature drops when I pour it onto the print by 10-15C but this isn't enough to form crystals.

    Hot developer can strip out material from the paper. I've found, for example, that the gelatin in COT320 makes the developer slushy after a while. If this happens then simply filter the developer through a coffee filter to clean it up.
     
  7. padraigm

    padraigm Member

    Messages:
    98
    Joined:
    Feb 18, 2010
    Shooter:
    Medium Format
    Thank you so much for the advice guys i will try that.