Stop Bath.. How important?

[Alex Benjamin]

This thread gives a whole new dimension to the phrase "If it ain't broke, don't fix it."

Which, by the way, is the reason I'll keep going on with my 30 seconds of Ilfostop .

 

[alanrockwood]

I have complained in this thread about the lack of experimental results showing that acid stop bath provides superior negatives to the use of water as a stop bath. Well, I finally found a comparison, but it didn't show that an acid stop bath was better. It was a very small and informal study, but it found no difference in film processed using an acid stop bath vs. water.

Here's the link.

Stop Bath? or Not?

Whether or not to use a stop bath in B&W processing……

blog.hmlai.com

As an aside, there have actually been two types of claims that an acid stop bath is superior to a water stop bath, 1) that It provides superior negatives (and/or prints), or 2) that it preserves the fixer. Sometimes it is unclear which effect an author of a post is referring to, although sometimes it is clear. There are also two types of applications, 1) film developing and 2) print developing, and it is not always clear which application the author of a post has in mind. Therefore, to reduce confusion it would be a good idea when posting a comment to state which claim is being discussed (i.e. superior negatives (and/or prints) vs. preserving the fixer) also state which application is being referred to (i.e. film vs. print processing.)

 

[alanrockwood]

This thread gives a whole new dimension to the phrase "If it ain't broke, don't fix it."

Which, by the way, is the reason I'll keep going on with my 30 seconds of Ilfostop .

There's also the flip side of that coin, which is "if it ain't necessary then why do it?"

 

[Alex Benjamin]

There's also the flip side of that coin, which is "if it ain't necessary then why do it?"

As in "It ain't necessary spending so much energy questioning something that ain't not working"? I agree totally.

 

[Sirius Glass]

Stuff I learned here from others. I have never had the problem, but then I use Kodak film, Ilford film and Rollei IR 400 and not the post Soviet manufacturer. I also mix chemicals to the manufacturers' specifications.

Oh yes, PE wrote extensively about pin holes from improperly mixed stop bath. Do a search on this website.

PE wrote extensively about using stop bath, its advantages, when to use stop bath with color film processing. A little research could save a lot of speculation posting.

 

[BobUK]

That reminds me there was once a young homemaker named Alice whose procedure for making roast beef included cutting a small piece from each end of the roast. When Alice's very young and curious daughter asked why remove the ends of the roast Alice replied that she learned the procedure from her mother, and that she would ask her mother at the next opportunity. Alice's mother had a similar answer, "I learned it from my mother." Alice then decided to ask her grandmother the same question the next time she would visit her at the rest home. The mystery was finally solved! Alice's grandmother, who was by then quite old but still had a good memory, replied "My Dear Alice, when I was a young bride my roasting pan was too short to fit the whole roast, so I had to cut the ends off the roast to make it fit the pan."

I like that.

Older members will remember George Burns and Gracie.
When Gracie cooked a turkey, she put a large and a small one in the oven together.
Her idea was, when the small turkey was burnt, the big one was done.

 

[Mal Paso]

I like that.

Older members will remember George Burns and Gracie.
When Gracie cooked a turkey, she put a large and a small one in the oven together.
Her idea was, when the small turkey was burnt, the big one was done.

Who you calling older?
Say Goodnight Gracie.

 

[alanrockwood]

Who you calling older?
Say Goodnight Gracie.

Gracie was a comedic genius, and George was no slouch himself.

 

[RalphLambrecht]

Water Vs. stop bath and film development

In the last couple of months, I've seen odd density variations in my Plus-X and FP4+. On the long edges of each frame is a subtle area of increased density which runs the lenght of the frame.

I develop in a steel tank with steel reels of course. For the last couple of years I've been using water as a stop bath as I was told I risk pinholes in the film when using stop bath of too strong a concentration. Rather than determining the correct concentration, I switched to water as it is 'supposedly' as effective as stop bath.

I switched back to stop bath for my most recent roll of film and the density problem also disappeared. There were no other process changes. Is it possible that a water stop bath is less effective in stopping development at the edges of the film where it is in contact with the reels?

water is definately less effective in stopping the development action than stop bath. Not sure that this fact explains the density issue at the film edgethough.

 

[Philippe-Georges]

What is now the most important purpose of the stop bath (regardless what kind of composition) and why?
- stopping the development
- changing/adapting the pH
- washing away the leftover of the developer and/or to prevent a carryover
- creating an environment for better fixing
- regulating/influencing the further processing (for instance: acids are not that easy to wash out of the gelatine)

PS: I am not particularly asking which one is the best...

 

[koraks]

@Philippe-Georges it depends a bit as it can be a combination of the things you mention. Mostly, it's to stop development in order to accurately control development time and reduce the risk of uneven development. It does this by dropping pH to a point where virtually all developers become inactive.

In color processing, the stop bath can serve to get rid of the developer which might otherwise result in unwanted dye formation; according to @Photo Engineer, this might be the reason for the rather harsh stop bath in ECN2 processing (1% sulfuric acid as I recall).

Coincidentally, this may also help to prevent carry-over as well, which is relevant if in color processing a ferricyanide bleach is used, since this bleach would immediately oxidize all developer which would result in excess dye formation especially in the top layer of the film. However, in this particular instance, it's best to follow the stop bath with an additional wash step, and/or preferably a sulfite bath. But the stop bath will do much of the 'heavy lifting' of removing the developer.

(for instance: acids are not that easy to wash out of the gelatine)

That's not entirely accurate. You could think of gelatin as a mass of strands a bit like a plate of spaghetti. The gelatin 'strands' tend to contract a bit if you dunk them into an acid bath, which makes it harder for water to permeate the mesh and thus to wash out whatever hides in there (meatballs, perhaps). So it's not really the acid that's hard to wash out, but the acid modifies the gelatin in such a way that washing becomes more difficult. However, this process is reversible, so the moment the pH rises again, the gelatin will swell and become easier to wash.

 

[Philippe-Georges]

I asked this because in a lot of answers on this thread, different facts, statements and opinions are posted which could cause confusion.
Perhaps, this might be even more important, by this we all can finally establish a kind of a 'definition' that determines what a stop bath is and (should-) does, and a 'correct' modus operandi.

A round up, on this forum, of all kinds of stop baths, their applications, formulas and pro and contra, just for reinsurance.

BTW, you might remarked it or not, but this thread all ready counts 50 pages...

PS: under the influence of some of the answers here, I stoped using the buffered stop bath, and switched to water for film processing, and citric acid for FB paper, without any issues...

 

[koraks]

BTW, you might remarked or not, it but this thread all ready counts 50 pages...

I did notice.
This is also why I applaud your attempt to reach consensus on this, but that's quite obviously never going to happen.

 

[Carnie Bob]

If you are doing Llith prints or solarization an acid stop is important, water alone will allow critical unwanted development

 

[RalphLambrecht]

My tap water is as alkaline as some developers I've used.

More often that is a problem of the developing process
and proper agitation. With a water stop, dilution of
the developer and ph reduction are very swift.

I've stopped using stops of any sort. Instead I use
very dilute unadulterated sodium or ammonium
thiosulfate. The two have a near neutral ph.

interesting approach!

 

[Philippe-Georges]

...but that's quite obviously never going to happen.

Don't despair, the wonders are not yet out of the world...

 

[chuckroast]

I did notice.
This is also why I applaud your attempt to reach consensus on this, but that's quite obviously never going to happen.

It is generally true that the heat of the exchange is inversely proportional to importance of the subject.

Monochrome photography is best served by consistency and repeatability. It does not require expertise in quantum chemistry or 5 digits of precision. So what I do, I do ... er ... consistently.

In my case that means:

Film: Running water wash after development, temperature matched to the developer for 30-ish seconds

Paper: 6oz 28% Acetic Acid per gallon of water for working strength stop bath. Alternatively, I sometimes use white vinegar diluted 1+4.

These, of course, are immutable laws of the universe and anyone not doing things my way is a heathen and philistine ...

 

[Truzi]

I like that.

Older members will remember George Burns and Gracie.
When Gracie cooked a turkey, she put a large and a small one in the oven together.
Her idea was, when the small turkey was burnt, the big one was done.

In the States we have a station/network called MeTV that plays reruns of Burns & Allen (and other things). After hearing so much about them, it's fun to actually watch the shows.

 

[MattKing]

What is now the most important purpose of the stop bath (regardless what kind of composition) and why?
- stopping the development
- changing/adapting the pH
- washing away the leftover of the developer and/or to prevent a carryover
- creating an environment for better fixing
- regulating/influencing the further processing (for instance: acids are not that easy to wash out of the gelatine)

PS: I am not particularly asking which one is the best...

To serve as a never-ending inspiration for Photrio posts .

 

[alanrockwood]

water is definately less effective in stopping the development action than stop bath. Not sure that this fact explains the density issue at the film edgethough.

My comments below are meant to apply only to film development. I am also not concerned with edge effects in the discussion below.

It is true that an acid stop bath stops development faster than a water stop bath. However, "faster" does not necessarily mean "more effectively" if by that term one means "better" in the sense of better quality in the resulting image. On the other hand, if by "more effectively" one means nothing more than taking less time to stop development, then yes, an acid stop bath is more effective, but as I see it the only thing that matters is if there is a difference in the quality of the image when using one type of stop bath vs. another.

I have yet to see any results from well-controlled experiments showing that the image quality is any better when using an acid stop bath than when using a neutral stop bath. I haven't even seen experimental evidence showing that developer carryover (or alkali from the film developer) into the fixer is noticeably better (by any practical consideration) when using an acid stop bath compared to using a neutral stop bath.

As to the time difference in how long it takes to stop development, if a water stop bath takes longer to stop development than an acid stop bath then all one would need to do is cut the time spent in the developer by a slight amount to compensate for the effect. How much development time would need to be cut? I don't know, but my wild guess would be something in the range of 15 to 30 seconds to achieve the same density, and it probably depends somewhat on the film/developer combination. (I would not even be surprised if the same development time would be good enough, regardless of which stop bath were used.)

The time difference is something that could be easily determined by a few experiments. However, that's not even necessary if one is determining a personal film speed. One would simply go through that whole process of determining a personal film speed (of developing for different times) using water as a stop bath in exactly the same way as one would determine personal film speed using an acid stop bath, and the preferred development time will come out in the end without ever needing to do a comparison between acid stop vs. neutral stop.

 

[chuckroast]

<SNIP>

The time difference is something that could be easily determined by a few experiments. However, that's not even necessary if one is determining a personal film speed. One would simply go through that whole process of determining a personal film speed (of developing for different times) using water as a stop bath in exactly the same way as one would determine personal film speed using an acid stop bath, and the preferred development time will come out in the end without ever needing to do a comparison between acid stop vs. neutral stop.

Indeed, that's exactly what one could do. But my guess is that the difference between stop and running water would so small as to make it practically irrelevant.

When I switched from acid stop for films to just a continuously (vigorously) running water bath I did not change my development times and saw no significant differences before- and after. I realize there are people that want to measure things out to 0.0001 DU and blessings be upon them. I, however, have no such interest. Upon ending life, I am pretty sure God isn't going to say "You didn't shoot enough test negatives" ...

 

[MattKing]

So Alan,
What about optimizing process capacity and helping minimize time and fixer waste.
Are those valid reasons to use stop bath?

 

[Rolleiflexible]

To serve as a never-ending inspiration for Photrio posts .

I still think you and I were twins separated at birth.

 

[MattKing]

I still think you and I were twins separated at birth.

Sadly, Mom is not around any more to ask .

 

[alanrockwood]

So Alan,
What about optimizing process capacity and helping minimize time and fixer waste.
Are those valid reasons to use stop bath?

Those are interesting points and they can valid reasons to (optionally) use acid stop bath in place of water stop bath, IF the effects have been experimentally validated. Are you aware of any experimental work that validates those claims? For example, is it actually faster to process a roll of film if one uses an acid stop bath rather than using a water stop bath? Does using an acid stop bath preserve the fixer lifetime by an amount that makes a practical difference?

I say "optionally" above based on an assumption that the quality of processed film is the same using either stop bath. If this is true other factors may give the nod toward one choice or the other, hence the choice of word "optionally". If the quality of the developed film differs then for some people the quality factor may give the nod toward the choice that gives higher quality, regardless of the other factors.

I suspect that some of the things you mention are probably more important to a large commercial lab that processes a lot of film than they are to a hobbyist who might process a few rolls per month. For example, if using an acid stop bath extends the life of the fixer by, let us say 5% for sake of discussion, compared to using a water stop bath, does that really matter to a hobbyist? It might for some hobbyist, but not others. Similarly, if using a water stop bath adds, let us say 30 seconds for sake of discussion, to the overall time to process a roll of film does it really matter to a hobbyist?

On the quality issue, in one of my earlier posts I linked to a web page where someone did a test of water stop bath vs. acid stop bath. That person saw no difference in the results. If anyone wants the link to that post then just ask and I will try to track it down.

Also, photrio user "chuckroast" posted here a few hours ago that he saw no noticeable difference when switching to a water vs. using an acid stop bath, and that's without even changing the time for the stop bath step to compensate for a possible difference in the amount of time it takes to stop development in one stop bath vs. the other.