Stop Bath.. How important?

sanking · Aug 17, 2007

Snapshot said:
Hi All,

I've been using acide stop baths for my printing and developing. However, I've been considering using only water as my stop bath for film development. It's my understanding that the advantage that acid stop baths have is they completely arrest further development of the film. With water stop baths, however, there is some development (although greatly slowed) of the film. Nonethelss, it's my understanding that water bath allows the film to develop a small amount, which in some cases could improve acutance.

Would anyone care to post their thoughts or musing on the pros and cons of water stop baths? Thank you in advance.

Why not do both?

Start with water and let the film rest there for a couple of minutes. If there is any increase in acutance from enhanced edge effects with a water stop bath, two minutes should do it.

Next, pour the water out and pour in an acid stop bath. If it is true that the acid bath prolongs fixer life, you are covered.

Sandy

pkrentz · Aug 17, 2007

Stop Bath

I have used a 1 part vinegar (white) to 15 parts water (distilled) for years, no odor unless you stick you nose in it, no pinholes in film emulsion and it stops development right now, we are not stoping tanks here. Pat

Alan9940 · Aug 17, 2007

Years, ago, I used a very diluted mix of glacial acid acid for stop during film development; my dilution was much less than generally recommended at the time. Due to occasional issues with pinholes, etc, and the use of pyro-type film developers I seemed to naturally migrate away from acid stops to using water only. If you use alkaline-based fixers (e.g. Photo Formulary's TF-4), then acid stop baths really shouldn't be used. My vote is: use water.

Hope this helps.

Photo Engineer · Aug 17, 2007

Alan;

Pinholes should not arise from use of stop baths.

TF-4 is so heavily buffered at the active pH that a dilute acid stop will have little effect on the fix. In fact, the cloudy ppt. in TF-4 concentrate is the excess buffer to protect you from just such usage.

PE

pentaxuser · Aug 17, 2007

Just today I was re-reading "Essential Darkroom Techniques" published in 1987 by Jonathan Eastland who according to the flysheet was a professional photographer with 18 years of darkroom experience and ran an international news and features agency. He too mentions the pinhole effect but qualifies it like PE by stating too strong an acid bath may( not will) create such an effect.

He goes on to say that he found that the very weak effect of development action from the use of a water bath seems to have the effect of enhancing shadow detail without increasing neg contrast. In this context he was talking about Kodak's HC110 which has a syrupy consistency even at working strength and a tendency to stick to the emulsion, hence its continued effect in the water bath. Unfortunately he doesn't expand on the correct water bath process for this effect so there's no way of knowing how long the film was in the water bath.

Interestingly Mr Eastland does not say he ever had a problem with a proper strength bath nor that he ever had a proplem with an over strength acid bath.

When books are written it is often the case that the authors reflect the then thinking and in the context of photography, the state of films then and maybe for a few years before.

PE. Could it have been the case that until some time in the 80s, films were more susceptible to pinholes that has been the case more recently? Hence the acid bath creating pinholes issue

I used to use an acid bath for film but more recently have switched to water. It's cheaper and easier. It seems to me that if the dev time has been something like 10 mins or even more and the tank is drained properly and immediately filled with say 250mls of water, swilled round and dumped in a matter of seconds then any effect of continued dev in what is a very dilute dev must be very small and effectively eliminated on the second fill and dump.

I normally use 4 fill and dumps before the fixer and haven't seen any difference in the negs compared to using an acid bath.

pentaxuser

Photo Engineer · Aug 17, 2007

There have been virtually no documented cases of pinholes from carbonate developers and acid stops or fixes. Eaton gives it a passing mention in his textbook but that is about it.

When a film is too soft and is hit by acid after a carbonate developer, the result is not a pinhole, it is a set of visible blisters. I have demonstrated this in my workshop to the students. The blisters resemble those on human skin from sunburn and when they dry they form either a fish scale like surface or an actual run of the emulsion.

A pinhole would not be a direct result of the release of gas.

I have also done this experiment in laboratory controlled conditions to determine if it would be safe to move from Kodalk to Carbonate in the EP-3 process (from EP-C). It had no effect unless the coating was too soft to survive processing without a whole series of other effects.

Besides, no film from Kodak, Fuji, Agfa or Ilford were that soft for the at least the last 50 years AFAIK.

PE

MattKing · Aug 17, 2007

I repeat my earlier post:

(there was a url link here which no longer exists)

Matt

pentaxuser · Aug 17, 2007

PE. Thanks. Maybe just goes to show how something that may have had a very limited link with an actual happening which itself was then taken out of context becomes to be quoted as fact but is a myth.

The problem is always that it may have occurred a few times but be due to other factors and a spurious correlation is made.

In matters much more vital such as medicines one can begin to appreciate why randomised control trials involving 1000s are conducted before any meaningful conclusions are drawn.

pentaxuser

Snapshot · Aug 17, 2007

Well, it appears that a water bath doesn't give me an advantage over an acid bath so I'll continue to use acid for consistent results. However, I'm experimenting with pyro developers and a water stop bath is recommended so I'll use water in those circumstances. Thanks for the responses everyone.

dancqu · Aug 17, 2007

mhv said:
Water bath after developer has never killed anyone,
many people use it, and as many people use stop bath.

But not as many use no stop what so ever.
I don't bother with it at all. Develop then fix,
film and paper. I use all chemistry one-shot so
am not concerned with a build up of developer
in the fixer. Also ph shift is no issue. An acid
stop is for the purpose of maintaining the
acidity of an acid fix.

The short rinse in an acid stop does not wash out
the developer any quicker than plain water but the
acidity of the fixer keeps the accumulated developer
in the fix from being active.

The accumulation of developer is an issue with those
who use an alkaline fixer where-in the accumulated
developer is always active. Dan

nworth · Aug 17, 2007

Out of habit, I use two water rinses after the developer for film and a two percent acetic acid stop bath for paper. This has worked fine for more years than I can remember. Logically, it may be backward. After all, film development is what needs to be really stopped at a definite point - paper essentially gets developed to completion. An acid stop bath may give a little insurance against stain on the paper, and it may protect the (very slightly) acid fixer, but not much. In any case, it seems to work. This is not an area of great criticality unless something doesn't work. If that happens, you need to start again with the conventional methods.

Michel Hardy-Vallée · Aug 17, 2007

dancqu said:
But not as many use no stop what so ever.
I don't bother with it at all. Develop then fix,
film and paper. I use all chemistry one-shot so
am not concerned with a build up of developer
in the fixer. Also ph shift is no issue. An acid
stop is for the purpose of maintaining the
acidity of an acid fix.

The short rinse in an acid stop does not wash out
the developer any quicker than plain water but the
acidity of the fixer keeps the accumulated developer
in the fix from being active.

The accumulation of developer is an issue with those
who use an alkaline fixer where-in the accumulated
developer is always active. Dan

Yep, that's another scenario that make sense.

I think with the acidic/alkaline stop/wash questions, what matters is not whether a stop bath is inherently good or bad, but whether one's workflow makes sense or not.

fschifano · Aug 17, 2007

Well, I'll tell you. I have used an acid stop bath, mixed at the recommended strength, on films for many years. A while back, I experimented with using a water wash as a stop bath just to see if there was any appreciable difference in the negatives. The comparison films were shot under similar, but not identical, conditions, leaving some wiggle room there to argue my results.

Bottom line is that I really couldn't see a whole lot of difference in the negatives, and even less when it came to the resulting prints. The differences could easily be chalked up to the fact that my exposures were not made under identical conditions, small development time deviations, and maybe even the phase of the moon. What I did find though is that my fixing bath (acid fixer) did not last nearly as long without having used the acid stop.

The only complaint I have with indicating stop baths is the yellow dye that gets carried over to the fixer. I eliminate the problem by washing the film with a couple of changes of water between the stop and fixer. Everything works out fine.

And what's the story about the smell? I hear a lot of complaints about that, but I've got to wonder what else is going on. Stop bath, if used at the recommended strength, really doesn't smell all that much. True, there is that vinegar odor, but it should not be so strong as to be irritating to most people. If the smell is really bothersome, then perhaps something else is wrong and needs to be corrected. Maybe the stop bath is mixed up too strongly, or more ventilation in the work area is needed. For those who are extraordinarily sensitive to acetic acid, a good substitute is citric acid with no odor.

Ole · Aug 17, 2007

There is yet another way, which I've used with good results a few times:

No stop, and no fix!

Instead of pouring the developer out and the fixer in, I dump about a tablespoon of ammonium thiosulfate dissolved in a little water straight into the spent developer.

I figured that with a very dilute developer (like Rodinal at 1:100) the developer would be almost completely dead at the end of the developing, and what was left would be mostly some sodium sulfite and a little alkali. Since that's what an alkaline fixer contains in addition to thiosulfate, I decided it was worth a try.

Well - it works. In fact it works just great - with some developers, and not so great with some others. Rodinal is fine, Ilfotec HC not so fine.

Alan9940 · Aug 17, 2007

PE,

You are probably right about the pinholes and the cause-n-effect as it relates to using an acid stop bath. To be honest, I never bothered tracking down why I was getting the pinholes because I stopped using that particular film. Overall, I would say that I started using a water stop mostly due to my use of PMK for many years followed, more recently, by Pyrocat HD; and the fact that the dilution I was using was so weak it seemed pointless to continue using the acid.

As with most things photographic I guess it comes down to: whatever works for you.

Thanks, though, for the clarification that the pinholes were probably not caused by the acid stop bath. Should I ever experience this issue, again, I'll look elsewhere.

Vaughn · Aug 18, 2007

I have read arguments for using stop bath, such as:

"I am strongly opposed to the use of a water rinse as a "short stop" bath. There are some problems related to colloidal sulfur, and staining etc. I know some of you will decry my position saying that it never happened to me, however, it may be happening as we speak and you won't know about it for months or years to come."

"To begin with, acetic acid conditions and toughens gelatin without hardening it."

These statements were made by H. Lynn Jones in another forum. I quote them not in their support, but to get some sort of feedback as to their accuracy. Mr. Jones is a long time instructor and has worked in the manufacture of lenses, etc. He is knowledgable and worth listening to.

One last quote from the same discussion...

"I agree with Lynn, water may not show the signs colloidal sulfur, and staining on prints straight away however in time and especially on large prints problems can arise. Just ask any photo librarian or gallery curator and they will let you know exactly how much more longevity prints get when stop bath or acetic acid have been used."

I have never heard such opinions mentioned here in APUG, so I am wondering what PE and others think about the the effect on longivity that using water instead of stop bath might have on film and paper.

Vaughn

Roger Hicks · Aug 18, 2007

I am told by someone whose experience and knowledge I trust (though I have never tried to verify it experimentally) that if you photograph an even grey tone, and process without a stop bath, it is far more difficult to maintain evenness. He knew this because it was a 'party trick' at his college -- it may have been the London College of Printing, but I have forgotten -- that was used to persuade people that stop baths are not necessarily irrelevant.

I have never bothered to try to verify it because it is never visible in 'real world' negatives. For films, both he and I will either go straight from dev to fix, or use VERY weakly acidulated water -- a dash of glacial acetic acid in water, used one-shot -- between the two. I've not used 'full strength' stop bath in decades, not from fear of pinholes, but because I find my ways easier.

Paper is another matter. There, I use standard-strength stop bath, made up from glacial acetic (or currently, Tetenal 60% acetic, because it's easier to get) because the chemicals sit in the Nova tank and are re-used to within distant sight of exhaustion, unlike film processing. Strong acetic is so cheap that I just don't worry about the tiny added cost, or about chucking it out before it's exhausted.

Roger Hicks · Aug 18, 2007

Vaughn said:
"To begin with, acetic acid conditions and toughens gelatin without hardening it."

Dear Vaughn,

I'm not sure what 'conditions' might mean, nor, in the context of gelatine, can I see how you can 'toughen' without 'hardening': both, surely, can be achieved only by water reduction or breaking cross-linkages. My knowledge of the chemistry of gelatine is however lamentably poor: I have only the weakest understanding of the nature of isoelectric points, for example, and that, only when I am reading about the subject in a well-written text. Like you, I'd be interested to hear PE's comments on this.

Cheers,

Roger

Vaughn · Aug 18, 2007

Thanks for your replies, Roger.

The only thing I understand about the chemistry of gelatin is that it is very difficult to understand, LOL! An interesting substance!

Vaughn

Photo Engineer · Aug 18, 2007

Gelatin swell is minimized at a pH of about 4.5, which is where the acid stop bath (acetic acid) would be. Therefore, the tendancy for gelatin to scratch or abrade is minimized.

The tendancy to form stains and to form a dichroic image are minimized by a stop bath. In fact, a stop is beneficial in removing any amine containing developing agent from film or paper. In particular, metol is of note. Metol is slow to remove in water.

Papers develop much more rapidly than films. Therefore a stop is much more effective in getting a uniform image in paper than film in some cases. This is to be noted in the posts above. It takes 10 minutes or so to develop films, and some take longer depending on developer. Paper is moving at 10X that rate and must be stopped in a shorter and more effective fashion for just that reason.

PE

bessa_L_R3a · Feb 27, 2008

is stop bath essential?

Hi,

I've been developing using tap water instead of stopbath and the results are fine, but someone told me the negative keeps on developing unless i use stop bath.

does it keep on developing even after it's been hung out to dry???

fyi: i am developing 35mm 400 iso BW film with HC -110

Robert.

Fotoguy20d · Feb 27, 2008

I use water too - the acid stop irritates my lungs. The stop bath neutralizes the developer and stops the process. If you don't use it, the developing process continues until you pour in the fixer. It probably doesn't matter much if you have a reasonably long developing time, and you can compensate by shortening development time slightly. Also, I think the fixer will become depleted more quickly.

Kevin Caulfield · Feb 27, 2008

My understanding is that stop bath actually stops development more immediately than water does as the pH is lower. To some extent using a water stop does mean that there is still a minimal amount of development occurrring, but as long as you get the fixer in reasonably quickly, this should not matter. The film stops developing once it is fixed, so unless you forgot to fix it, it does not keep developing after it's hung out to dry.

MikeSeb · Feb 27, 2008

In a word, "no".

You don't need stop bath. Even if any meaningful continued development occurred in the water rinse before the fixer, it would likely be accounted for when you establish your development times through testing.

Even better is to use an all-alkaline processing workflow, with alkaline developer followed by water rinse and then by an alkaline fixer, such as the Formulary's TF-4. IINM this is the recommendation of at least Ilford, if not Kodak also. More archival, since it rinses cleaner for a given wash time, and obviates the need for hypo clear.

Pinholemaster · Feb 27, 2008

No, but some people like it.

Stop Bath.. How important?

sanking

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