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

Steve Goldstein

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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.
 

cowanw

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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
 

holmburgers

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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?
 

gordrob

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

What about vinegar, where does that lie?
Click to expand...

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
 

holmburgers

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DWThomas said:
Hmmm - I may have been less than clear there, vinegar is typically 5%.
Click to expand...

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..
 
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