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  #1  
Old 27th August 2009, 08:25 PM
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Default Stop Bath with acetic acid

Hi,
I would like to make a 3% working strength stop bath from a stock Acetic Acid 80% solution (not glacial acetic acid). Can someone tell me if my dilutions are OK.

I would mix 3 parts of the Acetic Acid 80% solution with 77 parts of water.

Thank you
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Old 27th August 2009, 08:51 PM
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That sounds about right, Jacques, but I would err on the side of making a weaker solution. Stop bath only really needs to be acidic enough to stop development, but not so strong as to damage the emulsion. I use Ilford IN1 indicator stop at 1/2 it's recommended dilution without any problems - it just needs to be changed more regularly.

A lot of people don't use a stop bath at all, just a rinse in clean water between dev and fix. I find using stop helps with consistency when making a batch of prints.

Rob
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Old 27th August 2009, 08:51 PM
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Looks right to me: 80% -> 3% = (80/3)-1:1 = 25.667:1 = 77:3.
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Old 27th August 2009, 08:52 PM
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Hi Rob,
Do you think I should make a 1% solution and then I will have the stock solution for longer.
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Old 27th August 2009, 08:53 PM
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Thank you guys, but like Rob mention. Is it too strong for nothing else than wasting products?
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Old 27th August 2009, 08:57 PM
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I believe 2% is normal so I would assume that 1% will be a good idea - especially if you do not keep it between sessions.
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Old 28th August 2009, 06:51 PM
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I use Ilfords’ Citric Acid Stop Bath at half its recommended strength.

I dump it at the end of each day - but may have to change it mid session if required

I do it to keep the odour down but have worried in the past about shocking the emulsion when going from alkaline developer to very strong acid.

There have been scare stories about the chemical shock causing emulsion to flake off - but I have never been sure if these were legitimate concerns with modern high quality emulsions or yet another one of the photographic urban myths we seem to have

Martin
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Old 28th August 2009, 06:55 PM
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I use Citric Acid from Silverprint, 20g per litre. Economical and non-smelly.
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Old 28th August 2009, 06:58 PM
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Quote:
Originally Posted by Barry View Post
I use Citric Acid from Silverprint, 20g per litre. Economical and non-smelly.
Hi Barry - the one Silverprint supply in powder form ?

Martin
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Old 28th August 2009, 07:04 PM
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Quote:
Originally Posted by Martin Aislabie View Post
Hi Barry - the one Silverprint supply in powder form ?

Martin
Yes indeed. I throw it after each session.
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