Water or Stop Bath

rowland_mowrey · September 22, 2004

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Moderator's notes - This thread has, regrettably, been locked from

further participation for the following reasons:

1. Numerous references to color processes which are irrelevant to this forum

and this thread in particular. Many of us have never and will never

do any color processing. So any such references only serve to muddy

the waters and tax our patience. If you ever find it impossible to

avoid a reference to a color process or material in the b&w forums be

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here. Otherwise I'm likely to delete it immediately. If I'm in

a good mood I'll send to you an e-mail explaining why I deleted your comment,

altho' I'm not obligated to do so - the guidelines for topics appropriate

to these forums is clearly explained before you ever write a comment.

Otherwise I'm likely to begin deleting entire paragraphs which may, unfortunately,

include information that is related to b&w photography in the interest

of keeping the discussion on track.

2. Lobbing of tactless sarcasm and innuendoes is seldom a pleasant spectacle

to watch; less so when most of the shots hit the net or go out of bounds.

Hey, I like hearing a well placed, barbed zinger as much as the next guy

but this thread demonstrates little more than caveman clubbing. It's

almost enough to make me want to watch hockey and believe me, that will never

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And if there's a moral to the demise of this thread it's that a manifesto

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Lex Jenkins

Moderator, photo.net b&w photography forums

The following begins the originating post for this thread, from Rowland

Mowrey:

Throughout this forum I have seen several posts stating that stop

baths after development are not desirable. I see that Anchell and

Troop are also against it.

I would like to address their comments on p103 of "The Film

Developing Cookbook"

1. the pH change from developer to stop can generate molecular heat

and cause grains in the film to clump.

I have never heard of this at all under any circumstances after 32

years at EK. I would like to have a reference cited for this

statement as they seem to have statements for many of their other

assertions.

2. Acid stop baths cause pinholes and reticulation with developers

containing carbonate.

In the time I spent doing process research, I heard exactly one

comment on this. With color paper using a carbonate P122 developer,

or some B&W and color films in DEEP TANK PROCESSES ONLY (note that),

the hydrostatic pressure caused bubbles to form in the emulsion as it

emerged from the deep tank which resulted in pinholes. This problem

ceased after about 1970 since most all manufacturers changed film and

paper hardeners so that they can survive higher temperature

processes. At no time did I ever hear of reticulation caused by stop

baths.

3. Acid stop baths cause excessive swelling which leads to a loss in

image integrity.

Never heard of this one either.

In any case, if this happened, do you think that acid stop baths

would continue to be manufactured? I don't think so! If stop

baths

did cause swelling and reticulation, it would be a snap to design a

hardening stop. In fact, the C-22 and P122 processes had them.

Stop baths promote uniformity by stopping development rapidly and

uniformly. Water stop baths can cause different results based on

water supply (hardness, softness, pH and etc. I know, I've run quite

a few experiments on washes following development).

If you are worried about swell, look more to your water supply for

the source of the problem, not the stop bath. OTOH, you can make up

a hardening stop. Oh, BTW, distilled water can promote swell due to

the absence of salts. As a rule of thumb, salts reduce swell.

As for hardeners, they should not be needed if you use modern films

or papers from EK, Ilford, Fuji, Konica, and Agfa. In any event,

alum hardeners should not be used without a stop, as the alum can

cause scum to form. They are ok fresh, but exhaust rapidly without

a

stop and then begin to verge on precipitation of the alum due to an

increase in alkalinity of the fix.

On page 121 of their book, A&T recommend glutaraldehyde and

succinaldehyde hardeners due to the problems with formaldehyde. The

only problem is that these compounds can also cause fogging of films

or papers unless neutralized before development (remember the E4

neutralizer?). They are aldehydes just like formaldehyde. They

do

harden, but they allow much more swell of the hardened gelatin due to

the longer carbon chain length. This has been studied by EK years

ago during the E4 process years. The gelatin is certainly hard, but

swollen more than with formaldehyde, as the carbon chains linking the

gelatin are 5 and 6 atoms longer respectively with these two

aldehydes.

So, after reading all of those posts, and getting to what appears to

be the source of some of the comments I have read here on the forum,

I thought it might be of interest to post my actual observations from

my years of research in this field.

I hope that my observations and experience help those of you that

have posted these questions time and again. I'm sorry if these

observations differ from those of A&T, but as I said, I have run the

experiments myself more than once.

With apologies to A&T.

Ron Mowrey

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al_divenuti · September 22, 2004

1)Well - I hadn't heard of this either but it stands to reason. Many acid-base reactions are exothermic and produce heat. If the chemical kinetics of grain clumping are a function of temperature (and probably other things) then an increase in grain clumping seems to follow. It may be (probably is) an imperfect analogy but sudden application of extreme thermal gradients causes grains to coalesce in many alloy systems.

2) I've heard numerous references to the reaction to carbonate alkali and acid stop baths inducing pin holes. In fact, I can say that this is the *only* one of the three concerns I had heard of before buying the Film Developing Cookbook. The colloquial term "pin hole" seems a poor (pore?) description, so perhaps this prompts the confusion.

3) Well, I'm not sure how the gelatin swelling impairs image quality per se, but as per #1 I would expect an exothermic acid-base reaction to cause the gelatin to swell simply from thermal expansion.

al_divenuti · September 22, 2004

Perhaps the image quality concern in #3 applies to reticulation...

rowland_mowrey · September 22, 2004

Al;

Actually, development itself generates heat in the emulsions of film and paper both, and the pH drops considerably during the development process. In some developers, the pH in high silver areas is quite low, in fact, acidic in some cases.

I have heard of development taking place at temperatures up to over 120 deg C without severe reticulation or clumping in a dry process, and up to 120 deg F in wet processes without clumping. I've done it in fact.

Pinholes from stop baths were never a problem except in the rare cases that I cited above. B&W papers never suffered from the problem even in the severest cases. Pinholes were either as cited above in very rare cases, or due to airbells (bubbles) during development itself.

Ron Mowrey

frank.schifano · September 22, 2004

Rowland:

You put it better than I can, but your observations mirror mine. I am only a hobbyist in this craft, but I have never had a problem using an acid stop bath. The only time I don't use it is if there is a specific recommendation not to, I use Diafine, since the manufacturer recommends against it. I ran a few trials for a while without stop bath and found that my fixer did not last nearly as long but encountered no other significant problems. The way I figure, stop bath is cheap and pays for itself in increased fixer life. I see no reason not to use it unless there is a specific recommendation not to.

bobmichaels · September 22, 2004

I've never used a stop bath for film. My reasons were totally unscientific as it was just something else to buy and deal with.

Since my negs are fine, I'm staying in the "If it ain't broke, don't fix it" school of thought. Of course, the same logic applies if you are using a stop bath.

Question: if you currently have good negs, is there any reason to use a stop bath, other than increased fixer life?

neal_wydra1 · September 22, 2004

Dear Rowland,

Thank you for your post. I like controlling when the development is complete. To date, I have never had any problems due to stop bath (or fixer for that matter), always due to human error.

Neal Wydra

titrisol · September 22, 2004

Your observations are excellent Rowland, and it's refreshing to see someone disspelling the myths most of us grow to believe and keep teaching the next generations.

I have for years used only 3 or 4 changes of water as stop bath, with no ill results in image or fixer life. I have, however, used acid stop ocasionally for film and almosy always for paper.

I guess the only reason I'd advise acid stop is if you are using alkaline fixer.

rowland_mowrey · September 22, 2004

Bob;

OTOMY, the only reasons to use a stop bath are:

1. Uniformity due to the variations in water quality around the world, agitation, and the variations in development rate with different developers.

2. Preservation of fix whatever the type.

3. Prevention of scum if you use an acid hardening fix.

I may think of more. I'll let you know if I think of them.

Ron Mowrey

jay_de_fehr · September 22, 2004

Reasons not to use a stop with film:

more chemical to buy, store, mix, dispose of

no observable difference in film processed without it

water smells better than stop bath

jtdnyc · September 22, 2004

Ron:

You mentioned in passing that distilled water can cause swell due to the absence of salts.

After my own seven-year absence from the darkroom, I'm planning to resume developing film this week and had planned to use distilled water. Way back when, I used to use tap water. My negs were okay but, I suppose, not perfect; however, I never determined whether my water supply was the culprit.

Now, I'm willing to use whatever is really best -- tap, distilled, even so-called Smart Water (distilled water with some salts added back in).

Any words of guidance?

Jonathan

kelly_flanigan1 · September 22, 2004

When employees here dont use acid stop bath; they get fired. The graphics art developer we still use is very alkaline; the acid stop makes the rapid fixer last way longer. When the acid stop is replaced with water; the fixer poops out early; and we get staining; customer returns. Having to redo customers work is bad. Having cocky employees who skip steps; and then dont check the fixer; and turn out crap work is bad too. One should understand when one can get away with just water as a stop; and know when ones fixer is till good. Blindly replacing a step can be dangerous. In pictoral and smaller negatives; we sometimes use a weaker stop; top reduce pinholing.

patrick_gainer · September 23, 2004

I have done some strange things, as everyone here knows. One would almost believe I deliberately tried to get pinholes and reticulation. I have had reticulation, but it was a long time ago, and I attributed it to drying film too slowly. When you use moderate heat in drying, the film does not heat until the water is gone due to the cooling effect of evaporation. I think a longer wet time is worse than a little moving, warm, air.

I use an alkaline fixer without either acid stop or plain water. It stops development right away, at least as quickly as a water bath. The developer carried over seems not to have any appreciable effect on life of an alkaline fixer such as TF4. Often, I pour fixer concentrate into the developer at the end of development in the amount of 1/16 to 1/8 of the developer, pouring out a little developer if there is not room in the tank. I have had no problems with uneven development, pinholes or reticulation with modern films. It is possible that the transition directly from alkaline developer to alkaline fixer is a lesser strain on the emulsion, but I have not seen any effects of such strains in acid fixers either, nor have I seen increased grain in one case or the other.

I am not recommending this process for precision work such as lithography, or that any long standing and effective process be changed. I am simply pointing out that, as Ron has said, many theories about what happens to film are based on ancient history, or superstition.

Surely I am sloppy sometimes, but often it is a matter of finding out for myself if a certain theory is fact. I was born in West Virginia, where montani semper liberi, and raised in Missouri, where one is supposed to say "Show me."

chris_waller · September 23, 2004

Ron, glad you raised this issue, it's caused me a few sleepless nights. I have always used an acid stop bath (Kodak Indicating) and have never had a problem with pinholing even with developers using carbonate as the alkali. Having said that when using Jacobson Pyrocatechin I did use a water stop bath as advised. The argument re: the generation of heat, while theoretically correct, I doubt that the heat generated by such small amounts at such high diltuions could generate sufficient heat to cause the effects claimed. As for the effects of pH, gelatin contracts to a minimum volume at pHs in the range 4.5-5.0. Acid stop bath may, when fresh, have a lower pH than this and thus cause swelling, but that can be remedied by buffering with sodium acetate. On the alkaline side gelatin swells moderately at pHs between 5.0-8.0 then more markedly at higher pHs. Thus I would expect highly alkaline developers to pose more problems with swelling that acid stop.

All that said I use Rodinal which contains the highly alkaline potassium hydroxide and yet use an acid stop but have never experienced reticulation.

chris_waller · September 23, 2004

As a P.S. perhaps I could direct readers to 'www.screensound.gov.au', and the section headed 'Gelatin'. It makes interesting reading.

rick_jones5 · September 23, 2004

Ron-great post. I was always a little skeptical about the A&T comments on acid stop baths but, afterall, they are the experts. From now on, to me, you are to be known as Rowland "R. Henry" Mowrey, and that is a huge compliment as far as I'm concerned. Would you expand a little on your subsequent comment "actually, development itself generates heat in the emulsions of film and paper both --". For quite some time I have played a little game trying to get the film developer temperature to start and end the same. No matter what I do it's always higher at the end of development. Even with a carefully controlled water bath, a temperature stabilizing presoak and very little direct hand contact with my 32oz stainless tank the temperature will rise .2 to .5 degrees. I could never figure out why this was happening. Could the heat generation you referred to be enough to account for the temperature shifts I'm seeing or is something else causing this? Incidently, I realize controlling developer temp within 1 degree is probably all the control anyone needs but, as I said, it has just been a game I play.

oskar_ojala · September 23, 2004

Very interesting. I have not read the book in question myself, but I haven't had problems with using an acid stop (I've had prints from 35 mm mistaken to be from medium format by other photographers, so I guess image quality has not been compromised...)

garrylewis747 · September 23, 2004

Wallace Hanson wrote ("The Great Stopbath Squabble";Pop Photo;1975)an article in which he detailed experiments, by himself, trying to explore/create these very touted effects. He was unable to produce any of the defects often cited by the anti-acid proponets.

I've cited this article over the years, but the stopbath myths, like the energizer bunny,just keep on going.

As to extra cost, smell. and time- can't argue against that.

patrick_gainer · September 23, 2004

In order to avoid any temperature rise during development, it seems to me that one would have to avoid agitation. The mechanial energy of agitation is converted into heat. That would be a minimum requirement, and it does not take into account heat due to chemical reactions.

If a rise in temperature is a consequence of successful development, why worry about it? If you are going to worry about it anyway, then reduce the temperature of the water bath to take away the heat of mechanical motion and chemical reaction, but IMHO it will be a waste of resources. Sometimes it's better not to know too much.

Ascorbate developers reduce the pH locally by generation of acidic bromide and dehydroascorbic acid. That is the source of the edge sharpness and of part of the difference between ascorbic acid and hydroquinone. I have seen no sign of increase in grain or reticulation or any other cause for worry when using ascorbic or erythorbic acid developers.

john_finch · September 23, 2004

Hi Rowland, Fascinating, thankyou for taking the time out to dispell some of the myths with hard evidence. However, with fear of opening up this thread to a different (but closely related topic)I thought we were all over acid rapid fixers now that we have such good alkaline fixers like TF-4? I believe alkaline fixers wash out of the emulsion more easily and, therefore, improve archival permanence of our negatives? The price of alkaline fixers is pretty much the same as acid ones and surely their improved washing characteristics mean they are to be promoted? We do not use acid stop baths with alkaline fixers (which can be used with any developer - not just staining/tanning soups).Water stops film developing at no cost and no effect on the final product (as long as you are consistent and have factored it into your developing time - the change is miniscule) and alkaline fix is the way forward I would have thought?

Your comments on these beliefs/opinions would be welcome sir.

peter_svensson · September 23, 2004

Patrick, have you tried skipping the stop bath when printing as well? Wouldn't mind getting rid of one of the trays....

kirk_keyes · September 23, 2004

Partick wrote, "Ascorbate developers reduce the pH locally by generation of acidic bromide and dehydroascorbic acid."

Patrick - perhaps you made a typo in that sentence, but I think you'll find that bromide itself is not acidic. It is in fact a weak base, which when combined with a hydrogen ion which is considered a strong acid, makes a compound, HBr, which is a very strong acid. But bromide ions themselves are not acidic in aqueous solutions.

Measure the pH of a sodium bromide solution (weak acid combined with weak base = neutral aqueous solution) to demonstrate this.

Perhaps you meant that the release of bromide by the action of the ascorbic acid on silver bromide causes an acidic condition?

kirk_keyes · September 23, 2004

Chris - excellent link - Thanks!

conrad_hoffman · September 23, 2004

Ron, expanding on John's comments, A&T also claim that non-sodium thiosulfate fixers must be used to correctly fix modern films. Though I now use TF-4 for film, I've never had a bit of trouble using plain 'ol Kodak powdered fixer, and I still use that for RC prints, in spite of the lack of recommendations for it. I claim that there is absolutely no problem using standard acid hardening fixer (fresh, 2-bath preferred for fiber papers) if correct wash procedures are followed. I've never had any problem with selenium toning after washing either- I'd never go directly from the fixer to the toner, as it exhausts the toner faster. Comments?

lowell_huff1 · September 23, 2004

I agree with Mr. Mowrey. Water is not a STOP BATH! The purpose of stop bath is to change the pH which halts development in the emulsion; also when using HYPO or an alkaline fixer, the stop helps to buffer them against alkaline "build-up". Acid fixers don't need a stop because they are "stop-fixes" by definition. Many people prefer to use them anyway.

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