"TO STOP OR NOT TO STOP: THAT IS (no longer?) THE QUESTION"

[David Lyga]

Hamlet did not have film to develop, but we do. (Besides he was a Prince, busy contemplating a revenge, of sorts.)

Every once in a while the question comes up as to whether a post-development water bath is sufficient to stop development. Many (including me) have feared that a bit of development would continue in a neutral water bath, unlike in the normal acid stop bath. However, lowering pH does not necessarily remove developer, it just makes it more acidic. In color work, actually removing the developer is necessary, as bleach and developer do not mix well. But this thread is primarily about B&W, thus my testing is along only those lines.

I have performed a test, several times just to be certain, that I hope to be definitive for both film and paper. My choice of film is Kodak ImageLink microfilm. I chose this film because even a slight increase in development time causes density to accumulate faster than with other films. I wanted irrefutable, air-tight data.

For the film test, I gave adequate exposure, then developed for slightly less than required for normal tonal rendition. That way, there was plenty of ‘room’ for more density to form if there was developer present for that density to accrue. After three minutes of development I immediately cut the frame in two and plunged one half into stop bath. The other half I simply placed into clean water and let stay for three full minutes, undisturbed. During that three minute interval I fixed the first half. Then, after the three minutes were up, I placed the second half into stop bath and then fixed normally, all in complete darkness.

I washed the two halves and dried them. Then I compared. There was absolutely no difference in density.

For paper, I did this: I cut off a small rectangular piece of paper and fully exposed it to room light. Then, in darkness, I developed it for about half a minute, enough to cause only medium density to form. Again, still in darkness, I cut the rectangle in half and plunged the first half into stop, then fix. The second half I placed into clean water and let it sit, undisturbed for three minutes, then stopped and fixed. After washing and drying, I compared. Again, there was absolutely no increase in density with the water bath treatment.

In the pictures, ‘WB’ shows which half got the water bath after development.

No increase in development happened once that film or paper hit the water. Not giving either agitation readily allowed any residual developer to act. The film and paper might have sill felt slippery because of the still high pH, but the developer was effectively neutralized once either hit that water. To me, at least, this definitively proves that development continuance is not a justifiable worry with the omission of the stop bath.

However, where problems can manifest are when the same water bath is used in, say, printing, and that water bath accumulates quite a bit of developer. It might, then, become a dilute ‘developer’ in its own right. (I am not setting working standards here, merely being theoretical with my test.)

There is also a question that I have which seems to fit well at this point: Why does the pH in the whole process have to ever be lower than seven? Can alkaline fixers (see here):

http://www.monochromephotography.com/section233148_83765.html

work just as well, even BETTER (see the advantages listed in that link), given the data in the enclosed link? Why does there have to be ANY acid at all? Comments? - David Lyga

 

[Xmas]

Hamlet did not have film to develop, but we do. (Besides he was a Prince, busy contemplating a revenge, of sorts.)

Every once in a while the question comes up as to whether a post-development water bath is sufficient to stop development. Many (including me) have feared that a bit of development would continue in a neutral water bath, unlike in the normal acid stop bath. However, lowering pH does not necessarily remove developer, it just makes it more acidic. In color work, actually removing the developer is necessary, as bleach and developer do not mix well. But this thread is primarily about B&W, thus my testing is along only those lines.

I have performed a test, several times just to be certain, that I hope to be definitive for both film and paper. My choice of film is Kodak ImageLink microfilm. I chose this film because even a slight increase in development time causes density to accumulate faster than with other films. I wanted irrefutable, air-tight data.

For the film test, I gave adequate exposure, then developed for slightly less than required for normal tonal rendition. That way, there was plenty of ‘room’ for more density to form if there was developer present for that density to accrue. After three minutes of development I immediately cut the frame in two and plunged one half into stop bath. The other half I simply placed into clean water and let stay for three full minutes, undisturbed. During that three minute interval I fixed the first half. Then, after the three minutes were up, I placed the second half into stop bath and then fixed normally, all in complete darkness.

I washed the two halves and dried them. Then I compared. There was absolutely no difference in density.

For paper, I did this: I cut off a small rectangular piece of paper and fully exposed it to room light. Then, in darkness, I developed it for about half a minute, enough to cause only medium density to form. Again, still in darkness, I cut the rectangle in half and plunged the first half into stop, then fix. The second half I placed into clean water and let it sit, undisturbed for three minutes, then stopped and fixed. After washing and drying, I compared. Again, there was absolutely no increase in density with the water bath treatment.

In the pictures, ‘WB’ shows which half got the water bath after development.

No increase in development happened once that film or paper hit the water. Not giving either agitation readily allowed any residual developer to act. The film and paper might have sill felt slippery because of the still high pH, but the developer was effectively neutralized once either hit that water. To me, at least, this definitively proves that development continuance is not a justifiable worry with the omission of the stop bath.

However, where problems can manifest are when the same water bath is used in, say, printing, and that water bath accumulates quite a bit of developer. It might, then, become a dilute ‘developer’ in its own right. (I am not setting working standards here, merely being theoretical with my test.)

There is also a question that I have which seems to fit well at this point: Why does the pH in the whole process have to ever be lower than seven? Can alkaline fixers (see here):

http://www.monochromephotography.com/section233148_83765.html

work just as well, even BETTER (see the advantages listed in that link), given the data in the enclosed link? Why does there have to be ANY acid at all? Comments? - David Lyga

HiDavid

Three points

Stop (acidic) may be necessary if a print is going to be stained without... even if the risk is low.

If you agitate and/or use a double bath the amount of residual developer is going to be low.

Some emulsions are going to be or may be damaged by a too acid stop when they are

non prehardened film or
previously in carbonate alkali developer

especially if you don't temper

You might want to be aware rather than finding out the hard way.

Noel

 

[David Lyga]

XMAS (Happy Easter, or such):

I do not understand how stain could result if the water effectively eliminates the developer. (You seem to have made a case both supporting me and refuting me. Confused.) - David Lyga

 

[David Lyga]

Thanks Michael, you lend legitimacy to this but also posit proper caveats. Theory is different from practice in some, and this, instances. - David Lyga

 

[David Brown]

To me, at least, this definitively proves that development continuance is not a justifiable worry with the omission of the stop bath.

And yet, water-bath development is a long documented technique for controlling contrast in both film and paper, where development does continue in the water. I don't use it, but I've seen water bath with paper demonstrated by Les McLean.

Ansel Adams discusses this in both The Negative and The Print, Steve Anshell in the Darkroom Cookbook, and McLean in his book. I am almost certain there are other sources as well.

 

[MattKing]

An acidic stop bath helps extend the life of acidic fixers.

 

[pentaxuser]

For the film test, I gave adequate exposure, then developed for slightly less than required for normal tonal rendition. That way, there was plenty of ‘room’ for more density to form if there was developer present for that density to accrue. After three minutes of development I immediately cut the frame in two and plunged one half into stop bath. The other half I simply placed into clean water and let stay for three full minutes, undisturbed. During that three minute interval I fixed the first half. Then, after the three minutes were up, I placed the second half into stop bath and then fixed normally, all in complete darkness.

I washed the two halves and dried them. Then I compared. There was absolutely no difference in density.

David Lyga

Interesting experiment. My conservative( with a small "c") frame of mind suggested that one diffusion over 3 mins might have produced a slight difference but what this seems to reinforce is the point made by Ralph Lambrecht and maybe others which is that it is diffusion over time that seems to have the stop effect rather than simply quantity of water and number of changes of water

My three fills and dumps with maybe 10 inversion agitations in each cycle might be slightly quicker but uses more water and is no more effective or so it would appear.

pentaxuser

 

[Xmas]

XMAS (Happy Easter, or such):

I do not understand how stain could result if the water effectively eliminates the developer. (You seem to have made a case both supporting me and refuting me. Confused.) - David Lyga

HiDavid

I was repeating received advice for your information not trying to compromise or sway your experiments.

Normally all the commercial films are prehardened, but some strange ones might not be

poly pan maybe not
some if the ortho I use maybe not
Adox CHS 100 (type I ) was caveated - to not use a strong (>1.5% from memory) acid stop on the box and to handle with care when wet, think the typeII is.

So your experiments are ok but any general recommendations you might make may need care.

eg not everyone reads writing on boxes my chum opened a box of ilfords bulk in daylight ignoring the only open in dark room in eight languages on the label, think he only knew two of them...

The acid stop for paper may be for risk with tongs donno I'll try and find documentation next.

 

[NedL]

Hi David,

Interesting that you happened to post this today. This morning I developed two rolls of tri-x, the first with acid stop bath as I usually do, and the second with water stop. The second roll was developed with diafine and the instructions provided specify to use a water stop bath for 30 seconds. I guess this might be because part B of diafine is very alkaline and an abrupt dunking in acid perhaps could cause some kind of trouble, but I don't really know.

I mostly think of it like Matt said, that the acidic stop will help my acidic ( ilford rapid ) fixer last longer... with that in mind, I filled the tank with a second rinse of water for a total of 1 minute of water before fixing.

The place I've read the strongest message about development continuing after going into a water bath is with toning... I've looked for it with my selenium toning but have never been able to see it, but then I use a pretty dilute selenium toner and go for a long time.

 

[Bill Burk]

Hey David Lyga,

Nice experiment. I do occasionally worry about what can happen if there is an abrupt drop in pH going straight from developer to acid fix, so I like a nice mild acid stop bath in-between. I "believe" it stops me from having black spots on my prints from bubbles forming in the emulsion when an intense acid reacts with an intense alkali. But I don't know. Water is probably just as effective.

And when it comes to water bath development. You will NOT expect highlight density to increase, since the highlight's developer supply is quickly consumed... but the shadow density may increase during those three minutes. I don't see that as a bad thing in any case.

 

[RalphLambrecht]

my compliments on spending the time to test and sharing your resultsI want to positively stop development after a given time for consistency and hence my preference for a stop bathbut I have a small concern withcarbonate containing developers to generate carbon dioxide bubbles in the emulsion,which could create pinholes in the negative.Therefore,I've settled fora more diluted acid stop bath()1%). that seems to give me the best of both worlds(stopping development without the danger of pinholes

 

[fotch]

I just follow the instructions from the manufacture, ie Kodak, Ilford, Agfa, Adox, etc. Never have had problems.

 

[David Lyga]

OK, great feedback. And, to counter my 'wisdom': I will CONTINUE to use stop bath, albeit a VERY dilute one (even, gasp!, 0.25%), and only one-shot, to stop all development without worry or fear.

OK, again, my experiments 'proved' what I said, BUT...I do use VERY dilute developers (even my print developer is the equivalent of Dektol 1 + 5) so this can partly explain why my development stopped immediately: there was little developer to counteract.

If I had used Dektol 1 + 1, or the recommended 1 + 2, perhaps there would have been a slight carryover of increased density. It is a caution that is well worth mentioning. In standard use, that 'extra' development for paper would probably be negligible, as paper is largely a 'to finality' process, but with some film there could be a slight difference with overall density, and this increase would favor the shadows, for which developer would be more available than for the highlights.

But, that said, my experiment did include a film that is VERY prone to acquiring density (and quickly). And my delay of three full minutes had to coax every drop of energy that remained on the film. I do think that I made a point here: there is no great worry about using water as an effective stop bath (unless you use the same water repeatedly in a printing situation where it can accumulate developer), but mere fear will cause most of us to choose to be safer with the (hopefully, dilute) acidic alternative. - David Lyga

 

[David Lyga]

"but with some film there could be a slight difference with overall density, and this increase would favor the shadows"

I meant on the negative, as you can see, Michael, but thanks, I should have further explained. - David Lyga

 

[yulia_s_rey]

An acidic stop bath helps extend the life of acidic fixers.

there was a time I skipped the stop altogether until I realized it was the underlying reason as to why my fixer wouldn't last as long as it should have.

 

[ic-racer]

An acidic stop bath helps extend the life of acidic fixers.

This ^

If you had a running bath water stop and a running bath of fresh fixer then no issue. However, the usual darkroom worker uses three static trays where exhaustion of any of the 3 baths is a constant threat. If you are going to eliminate safety steps, proceed at you own risk

 

[RalphLambrecht]

a stop bath does indeed protect the first fix,which the water bath cannot do very well.

 

[hacked - sepiareverb]

...I've settled fora more diluted acid stop bath()1%)...

This is my usual method as well.

I often used a water bath for printing on grade papers, with visible results.

 

[Doremus Scudder]

Just some observations:

Stop bath serves to lower pH quickly, therefore arresting development quickly. A water bath does the same thing, albeit more slowly. As far as controlling development goes, either method will work as long as it is done consistently.

The dangers of using a water bath are: 1. developer builds up in a tray of water used for a stop bath, raising pH and effectively turning it into a weak developer solution over time. Unless you change water all the time, the results will not be consistent. An acid stop is easier. Running water would work, but is wasteful.

An acid stop will preserve acid or neutral fixing baths. For alkaline fixers it shouldn't make much difference. That said, most alkaline fixers (for sure TF-4 and TF-5) are designed to work well with a conventional acid stop bath, so there is no reason one should not use one.

No stop bath will not remove developer from the emulsion. That takes extended washing. Washing times are not only predicated on removing fixer, but also removing residual developer. When using staining developers, my first fixer is obviously discolored by carried-over developer long before reaching capacity; so is the water in the holding tray before I transfer the negatives to the washer.

When using an alkaline fix, care must be taken to ensure that the film has cleared completely before exposing the film to light. Otherwise, carried over developer can be re-activated, causing fog and streaks/mottling. Don't ask me how I know this I now use an acid fix for film developing just to avoid any issues with carried-over developer.

There are 43 pages of worthwhile reading in the sticky thread on this very topic here: (there was a url link here which no longer exists)

I'm convinced that using an acid stop is not only more convenient, but an integral part of a "best practice" processing regime.

Best,

Doremus

 

[Xmas]

Well an acid stop is desirable with paper just in case it stains.

But a risk with non prehardened film, which lots of you may never use.

Or if you use a carbonate developer, which lots of you may never use.

The problems are a physical one of gelatine swelling dependent on pH and a carbon dioxide bubble, tempering the stop is a good idea to reduce swelling risk as well.

An acid stop does not really provide any function with film even if you use a plain hypo fixer.

Lots of people use a post borax bath after film
development to increase shadow density preferentially, a fast stop to development is clearly a bad idea for them.

Some films have caveats on acid stops in their data sheet. The most rescent was Adox 100 CHS type I it recommended water and caveated less than 1.5% acetic acid... it was non prehardened on a PET base. Really nice film but replaced by typeII.

Your concept of good practice is procustean unless you also provide the caveats.

And we have had people who damaged non prehardened film this year... the advice was don't prebath, temper and don't use an acid stop, they were doing all three exposed for significant emulsion damage.

I save the vinegar for French fries, do two tempered water stops and two plain hypo baths, Id claim that is best practice, for minium emulsion stress and archival permanence cause I do use non prehardened film and occasionally carbonate developers.

 

[RalphLambrecht]

please remember that sodium carbonate and borax are pretty common development acceleratorsand can be found in sstandard developers such as D76 and ||||Dektol. as Isaid. If you are orried about the acidicy of a standard stop bath,cut the acid level to 1%and enjoy tthe benefitsof more controlled developmentwithout false hope of uncontrollable afterdevelopment.It's good practice to control shadow density with exposure not development.