Making citric acid stop last..

Smudger · Jun 10, 2009

My citric acid stop,whether mixed as a concentrate,or a one-off working solution,develops life-forms within a few days.
Can anyone suggest an additive to inhibit this?
Yes,I know citric acid is pretty cheap,but not that cheap,and I'm even cheaper..

Photo Engineer · Jun 10, 2009

Add 1 g/l Benzoic Acid.

PE

nworth · Jun 10, 2009

Photo Engineer said:
Add 1 g/l Benzoic Acid.

PE

How about thymol?

Photo Engineer · Jun 10, 2009

No. I would not. It could cause smeary marks on the surface of the film or print.

PE

mrred · Jun 10, 2009

Smudger said:
Yes,I know citric acid is pretty cheap,but not that cheap,and I'm even cheaper..

Wouldn't white vinegar be cheaper? That would not spoil anytime soon....

Kirk Keyes · Jun 11, 2009

Or just make it up when you use it. I follow Pat Gainer's lead and use a couple spoonfuls into a tray of water. (OK - I just dump some in from the bottle. ;^) Citric acid is pretty cheap - and food grade it just fine for this use.

davidst · Jun 11, 2009

2-3% acetic acid is the old stop bath, not citric acid. Luckily that is about the concentration of cheapest generic vinegar from the supermarket, and very cheap. Use it time and again.

Wade D · Jun 11, 2009

I've only used citric acid as a one shot solution then down the drain it goes.
White vinegar when diluted properly may smell a bit but it does last longer
and is quite cheap.

davidst · Jun 11, 2009

No, the cheap vinegar is not diluted. It is already 2-3% and can be used many many times over. Depending how much alkaline developer it is trying to "stop"; that is how much developer is residual from draining the developer from the tank. So don't go buying lovely balsamics, just a really cheap white vinegar (1.5 L )is excellent.

davidst · Jun 11, 2009

After the developer is drained out of the tank, open your cheap plastic flagon of vinegar, pour it into the tank, as is. Move the tank, or upend, for about 30 seconds, even less. It stops the developer almost immediately. Pour the stop bath (vinegar) back in the plastic flagon, and put your chemicals away...labelled clearly, always best into a dark cool cupboard.

dancqu · Jun 11, 2009

davidst said:
2-3% acetic acid is the old stop bath, ...

My bottle of white says 5%. Were I to use a stop
of any sort I'd likely put about a tablespoon of the
5% into 500ml of water, give the roll a minute of
constant agitation then dump the it. Dan

Lowell Huff · Jun 11, 2009

We advise that if you use any Clayton fixers a stop bath is not necessary. Our fixers are "stop-fixes".

Martin Aislabie · Jun 11, 2009

I use only half the concentration (1+40) that my Citric Stop recommends but this is to avoid excessive odour (it isn’t very strong but I am very sensitive to it)

However, I only use the Stop Sol’n for the duration of a days printing session and then dump it

The cost of Stop Bath is almost nothing compared to the rest of the photographic process

Martin

fschifano · Jun 11, 2009

A citric acid stop bath has no smell at all. It also doesn't last very long, but there it is. White vinegar comes in at around 5% acidity, which is a bit too strong for use as a stop bath, Diluted with an equal quantity of water makes it just right for the task, but it does have an odor. There is no indicator to signal exhaustion, so you're best shot is to use it only a few times, then discard.

A proper indicating stop bath lasts a long time, and might even be more economical than re-purposing vinegar for the task.

Photo Engineer · Jun 11, 2009

An acetic acid stop bath is its own indicator. If the odor vanishes, it is no longer any good and should be discarded.

PE

mrred · Jun 11, 2009

fschifano said:
Diluted with an equal quantity of water makes it just right for the task, but it does have an odor. .

And I'll take an order of fries with that....

Smudger · Jun 12, 2009

Thanks to all,especially PE..

Making citric acid stop last..

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