What is the acid percentage of Kodak Indicator Stop Bath concentrate?

Discussion in 'B&W: Film, Paper, Chemistry' started by Steve Goldstein, Feb 20, 2012.

  1. Steve Goldstein

    Steve Goldstein Subscriber

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    I have a couple of old bottles of the concentrate but neither states the concentration. Is it 28%, or something else? I'd like to know so I can do some semi-intelligent experiments acidifying used alkaline fix for electrolytic silver recovery.

    Thank you.
     
  2. cowanw

    cowanw Member

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    Weight % - Component - (CAS Registry No.)
    Concentrate:
    85-90
    Acetic acid (000064-19-7)
    10-15
    Water (007732-18-5)
    < 0.1
    Bromocresol purple (000115-40-2)
    or
    Kodak indicator stop bath concentrate is around 95%
    You choose
     
  3. Bob-D659

    Bob-D659 Member

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    Closer to 95% or so.
     
  4. Mike Wilde

    Mike Wilde Member

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    Is auto store sulfuric not more affordable?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Acetic Acid is soooo much more gentle on the skin! :wink:

    PE
     
  6. bobwysiwyg

    bobwysiwyg Subscriber

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    Couldn't agree more. Sulfuric acid is nasty stuff to be avoided if not absolutely necessary for a particular application or function.
     
  7. holmburgers

    holmburgers Member

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    So diluted 1 to 63, does that mean a working stop bath is about 1.5% acid?

    What about vinegar, where does that lie?
     
  8. DWThomas

    DWThomas Subscriber

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    5% is pretty typical.
     
  9. DWThomas

    DWThomas Subscriber

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    Hmmm - I may have been less than clear there, vinegar is typically 5%.
     
    Last edited by a moderator: Feb 22, 2012
  10. gordrob

    gordrob Subscriber

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    I have always mixed mine at 16ml/L which is 1.6% Kodak's recommended dilution. Your 1:63 gives you the same dilution.

    Gord
     
  11. holmburgers

    holmburgers Member

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    Thanks DW, I meant to ask actually. So diluting vinegar 1:2 or 333mL/1L would be about right I guess.

    Thanks Gord... I actually prefer a mL/L measurement over this this:that biz!

    If one could get a hold of some bromocresol purple cheap, making your own indicator stop bath might not be too difficult.. :whistling:
     
  12. RalphLambrecht

    RalphLambrecht Subscriber

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  13. RalphLambrecht

    RalphLambrecht Subscriber

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    yes,1.5-2%acid for a working stop bath is about right. i use 15gof as corbic acid /literof water.