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Reusable stop bath formula from vinegar and sodium hydroxide

faberryman said:
Stop bath is so cheap I use it once and throw it away. I don''t see the attraction of using vinegar and additives. Just more stuff to have to store.
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It is probably time to explain when it is convenient to have a reusable stop. Let us say you process films occasionally and also do not want your bathroom smell with all kinds of chemicals. So, you process films in a dedicated space where there is no running water, and reuse four bottles stored on the spot, developer concentrate, stop, fixer and Photoflo. Then you go wash and dry film in to another room. The developer is glycol based one-shot and is dumped into a waste bottle, and other solutions re-used. Nothing is routinely dumped into the sink except residual fixer. Makes sense?
I understand that there may be no incentive to use acid stop with certain developers.
 
A series of comments from, I think, photo.net years ago. For what it's worth.
 

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isn't any indicator stop re-usable until the indicator goes purple ?
kodak indicator is ( unfortunately strong smelling )
sprint stop bath smells like vanilla and is indicated .. mixes 1:9 is simple to use, and reuse and re-use and
no nasty chemicals to deal with .. has a track record of 40+ years ...
 
If you want to reuse your stop bath for developing film, that's fine. Just keep track of how many rolls you run through it. It's still cheaper to use concentrated stop bath than white vinegar and additives. Still not seeing the attraction.
 

Sounds like a sales pitch, I am sorry. No attraction, as I probably will have to pay through the nose for shipping. My supermarket is much more accessible. But It looks as though the Sprint bath is actually a buffered citrate. Also, some people find the smell of the acidic sodium acetate quite pleasant, but it is definitely not vanilla.
 
In my experience, the downside of re-using some stop baths (in particular citric acid based ones) is that they provide an environment that encourages mould growth.
I use Kodak Indicator Stop bath for film, and Ilfostop for prints. The Kodak product is cheaper to use, but the Ilford product smells better.
I've found that I can mix up and store long term a 1+7 stock solution of the Kodak Stop without mould growth problems. Then when I develop film, I mix the working solution for use.
If I'm developing several batches of film, I'll dilute the stock to "normal" strength (a further 1 + 7 yields a total dilution of 1 + 63) and re-use the working solution for all batches that day. If I'm doing just one or two batches that day, I'll mix it half strength. In either case, I'll discard at the end of the day.
For prints and Ilfostop, I mix it normally to the suggested strength and will discard it after use unless I plan to print again the next day. If I'm planning on printing very few prints, I'll work with half strength solutions and discard at the end.
My approach gets value from the indicator when using it with prints, but not so much with film.
Mine is a temporary darkroom and I have limited space in a separate cupboard to store chemicals.
I wish that Ilfostop was available in half litre or litre bottles.
 
no sales pitch .. just been using their chemistry since 1981

good luck with the wheel, i mean stop bath you are reinventing !
 
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Why not just buy some citric acid crystals/powder? It's very cheap, and will take up less space than bottles of liquid concentrate.
 
DavidJRobertson said:
Why not just buy some citric acid crystals/powder? It's very cheap, and will take up less space than bottles of liquid concentrate.
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I have some. A pound of the powder takes more space than the bottles of liquid concentrate, and lacks the indicator that I do prefer. I can make it work, but with my circumstances, powdered chemicals are far from ideal.
 
MattKing said:
I have some. A pound of the powder takes more space than the bottles of liquid concentrate, and lacks the indicator that I do prefer. I can make it work, but with my circumstances, powdered chemicals are far from ideal.
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Fair enough, but I would think that pound of powder will go a lot further than a bottle of concentrate, so not exactly a fair comparison.
 
Gerald C Koch said:
Acetic acid stop bath has its own 'built in' indicator -- its smell. No smell it's no longer effective.
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I re-use mine, separately for film and paper, and this is what I go by.

For prints/paper, I find it very convenient to have bottles of working developer, stop and fix always ready and always at hand. And it doesn't suddenly turn alkali like flipping a switch, the vinegar smell slowly gets less noticeable. Just replace before you can no longer smell it - simple!
 
DavidJRobertson said:
Fair enough, but I would think that pound of powder will go a lot further than a bottle of concentrate, so not exactly a fair comparison.
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A pound is probably enough for 25 sessions of printing (4 teaspoons for 2 litres).
A 250 ml bottle of Ilfostop is enough for 10 sessions.
 
MattKing said:
A pound is probably enough for 25 sessions of printing (4 teaspoons for 2 litres).
A 250 ml bottle of Ilfostop is enough for 10 sessions.
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Blimey, another miracle worker. Citric acid has a bulk density of ca 0.9, so the maximum that fits in a 250ml bottle is about 225g. Into the zero space remaining you add enough water to dissolve . At 20ºC that would be about 450 ml. How are you going to get all that into a 250ml bottle? Put another way,the max of citric acid saturated solution fitting into a 250 ml bottle is 145g or about 3 1/2 oz
 
A few things that should be mentioned:

Not all dyes act as indicators.
Any indicator used for a stop bath must change color in the right range.
Any color change must be visible under safe light illumination. Bromcresol purple solutions appear colorless hen fresh and black when exhausted. That is why this particular indicator was chosen.

I might also add that indicator stop bath is useful only for tray processing.
 
I'm afraid you have misunderstood!
I am comparing the pound bag sitting on the shelf with the 250 ml bottle of store bought Ilfostop standing beside it.
The bottle is way more appropriate for my circumstances . If you saw how small my chemical storage area is, you would understand why.
If I use the powder, I'll be doling it out with a teaspoon each time I have a printing session.
By the way, I realize that my "10 sessions per 250 ml" estimate is off - it is actually 5 sessions per 250 ml, and that is using Ilfostop at half strength, which I only do if my printing session is short. Those are the circumstances where the indicator is of particular value.
 
Gerald C Koch said:
I might also add that indicator stop bath is useful only for tray processing.
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It also is useful when I use tubes and rotary agitation for print processing - particularly useful for contact proof sheets.
 
faberryman said:
Are you sure you are not confused. I have never seen Ilfostop in anything other than a 500ml bottle that looks like this:

https://www.bhphotovideo.com/c/prod...893870_Ilfostop_Stop_Bath_500ml.html/mode/edu
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You are right.
I've been doing all my calculations in this thread thinking that the little bottles of Ilfostop were 250 ml - they are of course 500 ml. I should know better than to rely on memory for that sort of thing!
I still wish they were available in 1 litre size though.
 
I still haven't heard a good reason for doing what the OP is suggests. It's a solution in search of a problem.
 
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