Amidol Developing Question

[Pawlowski6132]

I am developing my AZO in an amidol recipe. I normally will just use a water stop bath as recommended by the TF-4 fixer instructions.

But then I became interested in utilizing a water bath to help control contrast. Should I really be using a stop bath? Since I'm using an alkaline fixer like TF-4 does it matter what kind of stop I use?

Also, can someone turn me onto some information explaining the nuances of the water bath using Amidol and AZO?

thanx much

[Vlad Soare]

Water doesn't stop anything with amidol. The stuff is too strong. That's why the water bath technique works so well with amidol - the developer adsorbed in the emulsion continues to work under water. A plain water "stop" bath with amidol is just bath, no stop.
You really need an acidic stop bath with amidol to actually stop the development.

The water bath technique is explained on Michael and Paula's site, here.

[Pawlowski6132]

Water doesn't stop anything with amidol. The stuff is too strong. That's why the water bath technique works so well with amidol - the developer adsorbed in the emulsion continues to work under water. A plain water "stop" bath with amidol is just bath, no stop.
You really need an acidic stop bath with amidol to actually stop the development.

The water bath technique is explained on Michael and Paula's site, here.

Thanx much. I'll do a bit of research on this next question but, wonder if it matters to my TF-4 fixer if I use an acid stop or not. Hmmm.

[Merg Ross]

With Amidol I have always used a Citric Acid stop bath such as Kodak SB-8.
15 grams citric acid/1 liter water.

[Pawlowski6132]

With Amidol I have always used a Citric Acid stop bath such as Kodak SB-8.
15 grams citric acid/1 liter water.

I'm noticing a few people do. I wanted to continue to use TF-4 which is an alkaline based non-hardening fixer. It works great with my Pyro statined negatives and I didn't want to use two separate fixers; one for film and one for paper.

So, while I'm certainly open to using an acidic stop, and being a novice in photochemistry, I am wondering if there's an issue using an acidic stop with an alkaline fixer.

thanx much


BTW, I have some citric acid on hand so, I'll prolly use that.

I also have some OLD (i.e. 20+ years) gaecial acid. Can I assume that this is very stable and is still "good"?
Joe

[Merg Ross]

So, while I'm certainly open to using an acidic stop, and being a novice in photochemistry, I am wondering if there's an issue using an acidic stop with an alkaline fixer.

thanx much

Joe

I would avoid using an acid stop with the alkaline fixer. Use the water bath development and then go directly to the fixer. You may get a different answer, but that would be my procedure given the alkaline fixer.

[Jay DeFehr]

I don't use TF-4, but I'm familiar with the formula. I'd say the effect of using an acid stop with TF-4 is similar to using a plain water bath with an acid fixer; eventually the carried over solution will begin to affect the pH of the fixer, but in neither case would I expect that to happen before the fixer is exhausted. Keep in mind that a pH change, in itself, will not exhaust a fixer, or render it ineffective the way it would a developer. In other words, the pH of the fixer does not affect it's capacity, but might have other effects; on wash times, stain formation, dichroic fog, shelf life, etc. So, using an acid stop might shorten the useful life of TF-4, or it might not. I always err on the side of caution when it comes to fixer, and dump it long before this kind of issue is raised. In short, I'd say the effect of using an acid stop with TF-4 is negligible if good practices are followed.

[j.e.simmons]

I normally use TF-2 (another alkaline fixer) and when using amidol, I mix a couple of teaspoons of citric acid in about a liter of water as a stop. I have not noticed any problem. The citric acid smells much better than the acetic acid.
juan

[John Bowen]

Joe,

I use Azo/Amidol and TF-4 and now TF-5. I NEVER use a stop bath.

Some have written about having their Azo/Amidol prints turning pink with rapid fix. I have not had any of my prints turn pink with either TF-4 or TF-5. I've processed over 2,500 sheets of Azo over the past 5 years.

[Vlad Soare]

I don't know the formula of TF-4, but commercial fixers are usually well buffered. I think the effect of an acidic stop bath, while certainly real, is negligible for all practical purposes.
I'm using a basic fixer myself - just sodium thiosulfate, sodium sulfite, and a little sodium bicarbonate. I also use a 2% (give or take) citric acid stop bath. No problems so far. Admittedly, I have so far only used this home-made basic fixer with films, not papers, but I don't see why it would be any different with papers.
Besides, even if the pH of the fixer goes down, it won't affect its activity. It may start to smell when it gets too acidic, but it will still work.