Substitute for 3% acetic acid

Discussion in 'B&W: Film, Paper, Chemistry' started by Marco Buonocore, Oct 12, 2013.

  1. Marco Buonocore

    Marco Buonocore Member

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    I sometimes have to use a 3% solution of acetic acid to clear the sediment or "haze" I get on prints after doing sepia toning (with thiocarbamide). I find I only get this haze when I am doing full sepia, ie: bleaching all the way back and toning to completion.

    Anyways, the 3% acetic acid clears this. That tip must have been in the Darkroom Cookbook. I have literally gallons of Kodak Indicator Stop Bath, and only a small bottle of 28% acetic acid. Can I use the Kodak Stop bath instead? Does anyone know what the working strength of Kodak Indicator Stop Bath is?

    Thanks!
     
  2. Prof_Pixel

    Prof_Pixel Member

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    White vinegar is about 5% acetic acid.
     
  3. paul_c5x4

    paul_c5x4 Subscriber

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    Kodak StopBath MSDS gives 85-90% of acetic acid - Working strength solutions would be 1-5%.
     
  4. Gerald C Koch

    Gerald C Koch Member

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    The strength depends on the manufacturer. Some brands are only 4% so you need to check the label.
     
  5. Doremus Scudder

    Doremus Scudder Member

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    Kodak Indicator Stop should work just fine as long as the indicator dye has no effect on your prints. It shouldn't, since it has no effect on normally developed prints, but I don't do that much sepia toning, thus the disclaimer.

    Assuming that the Kodak Indicator Stop concentrate is 90%, you can just dilute 1+30 and get very close to (just under) 3%. Adjust as needed if the solution is too weak.

    Best,

    Doremus
     
  6. pentaxuser

    pentaxuser Subscriber

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    Does the Darkroom Cookbook say what the chemical link is between thiocarbamide, complete bleaching, full sepia toning and the creation of a haze and why 3% acetic acid is the cure?

    Thanks

    pentaxuser
     
  7. eclarke

    eclarke Member

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    Glacial Acetic Acid is pretty easy to get and pretty cheap..White vingegar is even easier!!
     
  8. Gerald C Koch

    Gerald C Koch Member

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    Depends on the amount. I don't know whether the cutoff is at a pint or a quart but 1 gallon is subject to HAZMAT charges. What most people do not realize is that glacial acetic acid is flammable hernce the HAZMAT charge. Buying the 80% form will not incur this extra charge.

    Food grade glacial acetic acid is available which suggests a food service supplier as a source. Curiously this strength is also available as kosher.
     
    Last edited by a moderator: Oct 13, 2013
  9. Gerald C Koch

    Gerald C Koch Member

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    Since the haze is cleared by acetic acid I would say that it is caused by calcium carbonate being formed from hard water. The toner contains sodium carbonate in addition to thiocarbamide.
     
  10. pentaxuser

    pentaxuser Subscriber

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    Thanks Gerald, that seems to make sense but it seems that it only happens to the OP when he does full bleaching but not partial bleaching and I cannot see how this is related. Maybe it is less a question of full bleaching and more a question of time since full bleaching will take longer as will full toning afterwards

    My other conclusion from what you have said is that it would also seem that if the water isn't hard then the haze won't happen. I have no idea how hard the water is in Toronto.

    The whole business of haze in relevant to me as in my part of the U.K the water is also classified as hard but there is hard and hard and Toronto water may have my water well beaten in the hardness stakes

    Am I on the right lines with my thoughts?

    Thanks

    pentaxuser
     
  11. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    I use a citric acid stop bath. 10g per liter. It doesn't smell as bad as acetic acid. Works well.
     
  12. Gerald C Koch

    Gerald C Koch Member

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    I also think that time in the toner explains the difference.
     
  13. Marco Buonocore

    Marco Buonocore Member

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    Thanks for all the responses - I was away on a cycling trip and am just back to my computer now.

    I'll try Kodak Indictator Stop Bath at a 1:30 ratio and see if it does the same thing. The "haze" clears so quickly - in less than 10 seconds. It is a necessary step for me, it seems.

    Just for the record, I use a ferri/bromide bleach (B1 from the DuPont Varigam formulas) full strength, and bleach the image back fully. The toner is a sodium hydroxide/thiocarbamide formula (T1). The "haze" is evident in the deep blacks when held to light. I suppose I could try and make these with distilled water and see if the problem is a product of the Toronto tap water.

    Again - thanks for the help!