Stop Bath.. How important?

[Andrew O'Neill]

The latest Film Developing Cookbook indicates that anything but the very freshest stop bath doesn't stop development much more quickly than water does. The purpose is more to conserve the efficacy of the fixer.

I generally just use distilled water, as a little bit of compensatory development is just fine, and when I'm developing with staining, acid stop bath is prohibited anyway.

There is absolutely nothing wrong with using an acid stop bath when using staining developers...including the use of acid fixers. koraks and I both tested the theory independently, and there was no affect on image forming stain. I use several staining developers, as well. All good. I regularly use acid stop and Ilford's Rapid Fix.

 

[Augustus Caesar]

The latest Film Developing Cookbook indicates that anything but the very freshest stop bath doesn't stop development much more quickly than water does. The purpose is more to conserve the efficacy of the fixer.

I generally just use distilled water, as a little bit of compensatory development is just fine, and when I'm developing with staining, acid stop bath is prohibited anyway.

Who re-uses stop bath? I make it fresh each time, for film.

 

[Andrew O'Neill]

Who re-uses stop bath? I make it fresh each time, for film.

If it's an acidic stop bath, I do, and so do a number of people I know... At the school I teach photography at, we use an indicator stop bath, and use it until its colour starts to change.

 

[Augustus Caesar]

If it's an acidic stop bath, I do, and so do a number of people I know... At the school I teach photography at, we use an indicator stop bath, and use it until its colour starts to change.

Why? Just a few drops in the solution is all you need. Discard after use!

 

[MattKing]

Why? Just a few drops in the solution is all you need. Discard after use!

You clearly aren't working with school budgets and teenagers
I mix the acetic acid based stuff as intermediate stock, which stores and keeps well. The intermediate stock doesn't smell nearly as bad as the concentrated near-glacial-acetic-acid strength stuff sold as Kodak Indicator stock, nor will spills of the intermediate stock solution damage things like laminate counter tops (the undiluted Kodak stuff does!).
Working strength acetic acid stop will keep reasonably well, but normally I'll either use it half strength and discard after use, or if I've got several rolls of film to develop over a small number of days, I'll mix it normal strength and keep it that limited time, use it, and discard thereafter.
For printing, I use the citric acid based indicator stop. It doesn't keep well.

 

[rcphoto]

Why? Just a few drops in the solution is all you need. Discard after use!

I use my indicator stop until it indicates it's no good. this hobby is expensive enough. If i can stretch something a little, I like to.

 

[Mal Paso]

I've always diluted glacial acetic acid to 28%, then again for use as was handed down by the Great Yellow Father. Subversives would have you use citric acid or nothing at all destroying the carefully curated aroma therapy a darkroom affords.

 

[Andrew O'Neill]

Why? Just a few drops in the solution is all you need. Discard after use!

20ml/litre is not a few drops...But as Matt said, you have no clue about running a high school photo program. Your way is not the way. Personally, I'll use stop bath until it stops feeling squeaky between my fingers.

 

[alanrockwood]

20ml/litre is not a few drops...But as Matt said, you have no clue about running a high school photo program. Your way is not the way. Personally, I'll use stop bath until it stops feeling squeaky between my fingers.

for film development, paper development, or both?

 

[Don_ih]

concentrated near-glacial-acetic-acid strength stuff sold as Kodak Indicator stock, nor will spills of the intermediate stock solution damage things

On Facebook a few years ago, a guy posted a photo of some shrivelled up film and asked what he could have done wrong. Turns out, he used undiluted Kodak stop as the stop bath. The film looked like burnt bacon.

 

[koraks]

The film looked like burnt bacon.

The smell I imagine would have been a distinguishing factor between the two.

It's a good example why in an educational setting you'd never, ever take concentrated acids close to students unless it's a tightly controlled lab environment.

 

[guangong]

I suppose at this point in my life force of habit compels me to continue using a stop bath made from glacial acetic acid. A small amount seems to last forever since the working solution is so diluted. Other than water, stop bath is the cheapest chemical component in the developing process. Why skip this step in development when it only takes 30 seconds?

 

[Don_ih]

Why skip this step in development when it only takes 30 seconds?

Because people like to think they have a say in what they do.

 

[Andrew O'Neill]

for film development, paper development, or both?

Both.

 

[Andrew O'Neill]

Because people like to think they have a say in what they do.

That's pretty much it in a nutshell.

 

[Sirius Glass]

If it's an acidic stop bath, I do, and so do a number of people I know... At the school I teach photography at, we use an indicator stop bath, and use it until its colour starts to change.

That is the only stopbath I use and I reuse it until the color starts changing.

 

[Sirius Glass]

Why? Just a few drops in the solution is all you need. Discard after use!

It takes more than a few drops and there is no need to discard after one use. Follow the directions.

 

[alanrockwood]

I suppose at this point in my life force of habit compels me to continue using a stop bath made from glacial acetic acid. A small amount seems to last forever since the working solution is so diluted. Other than water, stop bath is the cheapest chemical component in the developing process. Why skip this step in development when it only takes 30 seconds?

Or alternatively, why do an extra step if it is not necessary?

An acid stop bath might be necessary, or it might not be necessary to produce a superior outcome.

However, in my searching for the answer I have not found reports of experiments showing that one choice produces a demonstrably better outcome than the other, although I have found a lot of opinions expressed on the matter, mostly without referencing any outcome-based experiments to support the opinions.

 

[Andrew O'Neill]

Well, an acid stop does help to extend the life of acidic fixers.

 

[alanrockwood]

Well, an acid stop does help to extend the life of acidic fixers.

I can accept that, but I would like to find some experimental results that compared the life of acidic fixers when a water "stop" bath was used compared using an acidic stop bath (including how much difference it makes).

The reason I pose this question is that if it only extended the life of the fixer by (let us say for sake of discussion) 10% then maybe that's not enough difference for a hobbyist to worry about, though it might be enough difference for a a high volume user to worry about.

Also, assuming it is true that an acidic stop bath does extend the life of an acidic fixer by a significant amount, does this translate to higher quality for the processed films or prints, assuming of course that one does not use exhausted fixer?

 

[Andrew O'Neill]

I wonder how much water is required to effectively stop development, and reduce the alkalinity, before placing the film in the fixer. I'm thinking that it would take a few litres of water to do so...filling...agitating...dumping...filling...agitating...dumping, etc, etc... Sounds time consuming, and wasteful. I could not do that in the classroom darkroom.

 

[Don_ih]

I wonder how much water is required to effectively stop development, and reduce the alkalinity, before placing the film in the fixer. I'm thinking that it would take a few litres of water to do so...filling...agitating...dumping...filling...agitating...dumping, etc, etc... Sounds time consuming, and wasteful. I could not do that in the classroom darkroom.

For film? Probably a single filling of the tank. There'll be next to nothing left when you dump it. Any residual development that occurs because of what's left will be spent immediately.

You can see how much development occurs by shooting a strip of film, all exactly the same exposure of the same thing, develop half normally, but let the other half sit in plain water for 10 minutes after you dump the developer (just dump the developer and fill the tank with water). There'll be no significant difference.

A third sample could be develop, dump, fill with water, dump, wait ten minutes, fix. That one may be a bit streaky.

 

[logan2z]

53 pages, eh? (you can take the Canadian out of Canada.. .)?

If you think stop is necessary/useful, then use it. If you don't, then don't. What else is there to say?

 

[cliveh]

Andrew and I are both teachers and as said previously in this thread it depends on the throughput. If you have 60 students a day processing 10 prints each, a indicator acid stop bath is essential to avoid alkali from the dev ruining the fixer. If you are one person in a home darkroom, you may get away with a few changes of water.

 

[pbromaghin]

Both.

Do you use the same batch for both? Someone on APUG once recommended not doing so. Or is that not a problem for you?