Ilfostop working life..

For ages I've been using ilfostop until the indicator appears or a couple of months, which ever comes first.

I just read on the ilford pdf it has a working strength of 7 working days, I'm sure it was longer than this in the past! Is 7 days really right?

The other thing is I've been using it for colour prints now, the stop goes orange quite quickly due to contamination but seems to work fine. I have no idea what it's working strength with colour print processing is or if the indicator will still work.

Any ideas?

My school uses an indicator stop bath and they toss it with the fix. I think it's wasteful. Why would they put an indicator in if it had to be thrown out after 7 days? It's just acid after all. It's not going to go bad.

I assume your vinegar at home keeps beyond 7 days !
The only real problem should be that of neutralisation by developer - which is the purpose of the stop bath and that's what the indicator shows. I usually just top up with a little concentrate until the indicator turns back - if it needs more than 2% I make a new batch.

rossawilson1 said:

The other thing is I've been using it for colour prints now, the stop goes orange quite quickly due to contamination but seems to work fine. I have no idea what it's working strength with colour print processing is or if the indicator will still work.

Any ideas?

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I noticed this with RA4 and asked the question: How do you tell if stop has exhausted when doing colour prints? I don't think there is an answer except to throw it after a certain number of prints but I have no idea how many.

Essentially the odourless Ilfostop is citric acid. Home-made stop is usually about 15g of citric acid crystals per litre of stop. If you buy the crystals in bulk it should work out very cheap, even if you ditch the stop after one session of a few hours.

Home brew shops used to sell it in bulk and still do if you can find one nearby. I'd look for one in yellow pages before trying mail order to avoid the postage and packing cost.

pentaxuser

I diluted vinegar 1-2 or something like that and leave a pitcher next to my sink. Some water evaporates, so from time to time I top it off with water. It's been sitting there for 2 months.

How do you figure in a stop for RA-4? Kodak doesn't make one... I just throw my prints from the developer to the bleach.

tiberiustibz said:

How do you figure in a stop for RA-4? Kodak doesn't make one... I just throw my prints from the developer to the bleach.

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Kodak recommends using an (optional) stop bath of 2% acetic acid to prevent excessive developer carryover when tray processing. Personally, I've never had problems with developer carryover and, like you said, go straight from developer to bleach. In fact, using a stop bath may be detrimental to the working life of the bleach, as I think RA chemistry is designed to be pH neutral.