Ilfostop - gelatinous, stringy residues.

GLS · Aug 31, 2018

I have a bottle of Ilfostop which I'm getting near the end of, but is probably no older than 6 months. The thing is, I just used it and it has suddenly developed some weird stringy residues. I made up the working solution and managed to fish out the worst of it, and it appears to have worked fine, but it makes me want to throw out the remainder (fortunately probably no more than 60 mL or so).

Has anyone else encountered this, and if so is it a common problem with Ilfostop? Thanks.

Rudeofus · Aug 31, 2018

Ilfostop consists of Citric Acid, some indicator dye and an antifungal compounds to prevent mold growth. Unfortunately Citric Acid is highly liable to mold growth, and the antifungal compound only lasts so long. It appears in your case the antifungal compound became inactive and your stop bath concentrate started growing mold. Dump it and get a fresh bottle.

PS: If shelf life is an issue for you and if you can handle the odor, Acetic Acid based stop bathes may be better for you.

GLS · Aug 31, 2018

Hmmm, thanks. Despite the shelf life I'll stick with the Ilfostop for now as it works well. I could easily make up a dilute acetic acid solution at work, but the less odours the better really.

JPD · Sep 1, 2018

You could also buy Citric acid from the supermarket. It keeps forever.

GLS · Sep 1, 2018

JPD said:
You could also buy Citric acid from the supermarket. It keeps forever.

Yes that's true. I can buy 2kg for £9 from Amazon, which would make 200 litres of 1 wt% solution, making it about 1/20th of the price of buying Ilfostop...

Larry the sailor · Sep 2, 2018

I just used the last of a bottle of Kodak Indicator stop bath that I bought 24 years ago and started on a bottle that came with a bunch of darkroom gear I bought that is at least 18 years old. Still looks like it should and works fine.

MattKing · Sep 2, 2018

Larry the sailor said:
I just used the last of a bottle of Kodak Indicator stop bath that I bought 24 years ago and started on a bottle that came with a bunch of darkroom gear I bought that is at least 18 years old. Still looks like it should and works fine.

If only the Kodak stop was as odour free as the Ilford stop!
I use the Ilford stop bath for printing, and the (cheaper for me) Kodak stop bath for films.

NB23 · Sep 2, 2018

I rather like the odor.

I’m a huge vinegar lover, too.

mpirie · Sep 3, 2018

GLS - you could filter your stop bath through a coffee filter to remove any detritus, then carry on using it.

Mike

GLS · Sep 3, 2018

mpirie said:
GLS - you could filter your stop bath through a coffee filter to remove any detritus, then carry on using it.

Mike

Yeah I did consider something like that, but for such a small amount remaining it's not worth bothering with. I have gone ahead and bought a load of citric acid, so will just try a 1% solution as stop bath next time and see how it goes.

I imagine such a dilute strength should avoid any risk of causing pinholes?

Rudeofus · Sep 3, 2018

GLS said:
Yeah I did consider something like that, but for such a small amount remaining it's not worth bothering with. I have gone ahead and bought a load of citric acid, so will just try a 1% solution as stop bath next time and see how it goes.

You can filter out slimy goo, but not the fungus which causes it, and you certainly don't want to bring that fungus into your film.

1.5% Citric Acid stop bath is an established formula, therefore I'd expect it to work properly, especially if you use your 1% version just single shot.

removed account4 · Sep 3, 2018

hi GLS
you could always just rinse your film or paper with running water a little bit
before you put it in your fixer .. ive been doing that for IDK 30 years, with no issues .
while some LOVE stopbath cause it instantaneously stops development action
i'd rather have 1 less chemical in my darkroom to go bad, smell tumes of, dispose of or purchase ...
YMMV

good luck with your stop !
john

GLS · Sep 3, 2018

Rudeofus said:
1.5% Citric Acid stop bath is an established formula, therefore I'd expect it to work properly, especially if you use your 1% version just single shot.

Thanks for the link.

Ilfostop - gelatinous, stringy residues.

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