Stop Bath.. How important?

[alanrockwood]

By the way, I am going on a business trip starting Friday morning, so I might be able to engage this conversation only intermittently for the coming week.

 

[Q.G.]

Ian keeps saying water is OK,
but seems IMHO to interpret Kodak etc. as saying they are equivelant
PE on the otherhand clearly feels they are saying they are unequal
but acceptable options.

Is this such a hard concept to reconcile?

Water is OK. It is not IDEAL. It is NOT ideal because there is less of a safety margin....

Stops are preferable. They are not absolutely necessary.
In fact, they are ideal... but usually not absolutely necessary.

Thought about it, and yes: i'm sure it's impossible to reconcile.
It is possible to accept that there is a conflict between both views though. But reconcile, i don't think so.

I mean, you too haven't managed to, but have chosen a side instead.


And that (choose a side) is the only thing we can do, i guess.

 

[M.A.Longmore]

I think the best way to summarize this debate can be found here :
http://www.youtube.com/watch?v=7IU1bzZheWk

Enjoy The Weekend


Ron

From The Long Island Of New York, and the
Long Island @ Large Format Group, right here on APUG
.

 

[Ian Grant]

Ian keeps saying water is OK,
but seems IMHO to interpret Kodak etc. as saying they are equivelant
PE on the otherhand clearly feels they are saying they are unequal
but acceptable options.

Is this such a hard concept to reconcile?

Water is OK. It is not IDEAL. It is NOT ideal because there is less of a safety margin....

Stops are preferable. They are not absolutely necessary.
In fact, they are ideal... but usually not absolutely necessary.

Ray, I've never thought that they are equivalent overall because there are advantages in terms of fixer life, stopping development faster, but it does appear from Mason's comment that a stop bath or rinse is "Superfluous" that we are all giving the stop or rinse far more importance than is required. Fuji don't use either for mechanical processing of B&W films that says rather a lot.

But yes I do think they are close enough equivalents in terms of the overall processing of films and Mason and others are quite clear about that. there's no evidence of any effects on image quality and the long term stability of the films.

I totally agree with your comments, which you've summed up well, I'd add:


Ilford -Stop bath is preferable. They are not absolutely necessary (with films).
Kodak - very clearly say you can use either (with films) - which I find slightly odd as I'd have thought they would have taken the same line as Ilford

I believe that Ian and I both have a lot to contribute to APUG. It is unfortunate that sometimes we misunderstand each other or disagree. I place no significance on these situations and merely try to pass on what I believe to be correct, based on the literature and my long experience.
PE

Just to put the record straight Ron, PE, is disagreeing with what Kodak & Ilford recommend, that you can use water instead of a stop bath with films which is part of the OP's question.

Neither of us disagree with the fact that a stop bath will lengthen the life of a fixer, or stop development faster, I've said that in many posts in the thread. However talk of residual HQ is a smoke screen, particularly as the reference is to a Monobath which has rather different and more complex chemistry. With films a stop bath itself doesn't have time to remove all residual developing agent in the emulsion, so we need to be looking at the fixer and wash to help complete that.

As I've said before it's that simple - YOU CAN USE A WATER RINSE with film, safely. If Ron disagrees he should take that up with Kodak it's been a recommendation since Mees joined the company nearly 100 years ago.

_____________________________________________________________________________________________________________
This is Kodak's recommendations (again).

FINAL STEPS
Rinse at 65 to 75°F (18 to 24°C) with agitation in KODAK
Indicator Stop Bath or running water for 30 seconds.

That's up to date Kodak information in the current Tmax data sheet, and in other film data sheets as well.

So anyone who can't agree and reconcile those plain fact's needs to take up the argument with Kodak, not me. It's a simple yes/no answer whether you can use a water rinse instead of stop bath, and both Ilford & Kodak say yes.

Ian

 

[Steve Smith]

Based on all the information in this thread, I am going to carry on using just plain water. I can see that there may be some advantages to using a stop but I don't think they will be of any benefit to me - perhaps they will be to others.

This is for film only. For prints I will continue to use a stop bath.


Steve.

 

[clayne]

I can think of one small benefit beyond the obvious: you waste less water.

It's actually logistically easier to use stop-bath.

 

[Curt]

Based on all the information in this thread, I am going to carry on using just plain water. I can see that there may be some advantages to using a stop but I don't think they will be of any benefit to me - perhaps they will be to others.

This is for film only. For prints I will continue to use a stop bath.


Steve.

Me too Steve, it's what I do and it works just fine.

 

[alexmacphee]

My observations are only anecdotal in nature, rather than scientific observations, but I processed my first films in the mid sixties. A few had stop baths in the processing, but being a penurious schoolboy, the stop bath often had to give way to plain water. I've noticed nothing to indicate any difference in stability as the result of not using a stop bath ; I had far more problems with insufficient final washing than anything else. I worry far more about temperature control than the post-dev rinse, which is plain water and has been for decades for me. It's been an interesting thread, though it's not persuaded me to change my processing routine.

 

[Thomas Bertilsson]

Kind of like American politics...

But then again, I think if Republicans and Democrats actually agreed on something - it's time to worry.

Thought about it, and yes: i'm sure it's impossible to reconcile.
It is possible to accept that there is a conflict between both views though. But reconcile, i don't think so.

I mean, you too haven't managed to, but have chosen a side instead.


And that (choose a side) is the only thing we can do, i guess.

 

[Photo Engineer]

Was that a typo?
(post #126)

Anyway guys,
this topic has been beaten to a pulp!

Nothing much to learn here
(other than the unpublished Kodak science from PE' s noggin).

Ian keeps saying water is OK,
but seems IMHO to interpret Kodak etc. as saying they are equivelant
PE on the otherhand clearly feels they are saying they are unequal
but acceptable options.

Is this such a hard concept to reconcile?

Water is OK. It is not IDEAL. It is NOT ideal because there is less of a safety margin....

Stops are preferable. They are not absolutely necessary.
In fact, they are ideal... but usually not absolutely necessary.

Ray;

Thanks for the catch. That is a typo in my post #126.

Thanks also for an excellent summary of these posts.

PE

 

[Photo Engineer]

All I can say on my own behalf is that, I do not disagree with what Kodak or any other mfgr says. They say either can be used for film, but there may be consequences thereby making them unequal. They say that a stop should be used for paper.

PE

 

[Photo Engineer]

I think the best approach now for our sub-discussion is to take it in a series of small steps to best avoid misunderstandings or confusion.

Let us set up a coordinate system to help clarify the discussion. Let the solution be on the left and the emulsion on the right.

One implication of the model you have posed, together with the coordinate system defined above is the following. There is a net displacement of charge to the right. In other words, the emulsion is a slab of material that acquires a net positive charge because positively charged hydrogen ions have been transported into the emulsion. This leaves a net negative charge in the solution, most of which will be in a relatively thin layer near the solution-emulsion interface.

A related effect occurs with the hydroxide ion, though to a lesser degree. They diffuse from the emulsion toward the solution. This is because the the concentration of hydroxide ions is higher in the emulsion than in the solution. This process adds to the net positive charge in the emulsion, i.e. removing negative ions (hydroxide ions) from the emulsion increases the net positive charge in the emulsion.

We will consider the other ions to be relatively fixed in space because they diffuse much slower than hydrogen ions (and hydroxide ions.) This is of course an approximation.

With respect to the reaction between hydrogen ions and hydroxide ions, this has no effect on the local net charge balance. This is the result of charge conservation. For example, let us consider a single hydrogen ion (do you mind if I just call them protons?) in close proximity to a single hydroxide ion. Considering only these two ions and not any other ions that may be in the vicinity, the net charge of the proton-hydroxide pair is zero. If these two ions then react to form a water molecule there is no change in the net local charge. Therefore, with respect to the location of the charge distributions there is no need to consider the acid-base neutralization reaction. (There could be an indirect effect because the neutralization reaction may change the concentration gradients, which in turn can affect the diffusion rates, but this is a fine point that need not concern us at this point.)

Let us see if we can agree that this description is a consequence of the model you have proposed.

I can agree to a point.

There are other ions present such as Sodium, Bromide, Carbonate and Acetate to name a few, and listed in rough ascending order of size and therefore diffusion rate.

In any acid base neutralization of one proton and one hydroxide, there is an instantaneous charge imbalance at that site as a neutral water molecule is formed. This, in our example, would leave a negatively charged acetate ion somewhere on the left and a positively charged Sodium ion on the right, and they have to move somehow together. So, if it occurs on a grander scale over several square inches, but on a time scale of microseconds, then there is not much difference. I viewed it, when I first learned of these tests, as if I were seeing a high speed collapse of a row of dominoes.

Now, after looking up the data, I find that my 15" was conservative by a long shot. According to Henn and Crabtree, depending on pH and acid concentration, the reaction can be over in about 1 second throughout the entire emulsion. But, at the other end of the scale, 15" is not a bad guess when using dilute acid or when at a higher pH.

The original tests were done by imbibing the indicator dye and then adding the acid and measuring the change in the dye. Later we coated the dye and mordanted it in place.

PE

 

[Ian Grant]

Thank you Ron, and to clarify those consequences are to the potential life & throughput of the Fixer used. There's no possible potential later consequences for the film.


Kodak have no wash or stop-bath stage in their Versamat/Duraflo film processing, matching Fuji's equivalent, which ties in with Mason saying the stage is "superfluous". However Ilford do recommend a stop bath with their RT system if the processor has the facilities to use one, (I think their own machines used one), for the same reasons Mason cites, that a stop bath improves the potential stability & throughput of the Fixer.

Ian

 

[Photo Engineer]

Ian;

Please note that there are established limits for retained developing agents in film and paper. I posted the reference to work done with Monobaths above, but it has been done in a similar fashion for all types of processes. Since HQ and Metol are opposites in terms of one being a weak organic acid and the other a weak organic base, they do differ in their reactions to different pH values and have different wash rates.

I'm sorry that I still have not found any published works on this particular subject, but I assure you that it is part and parcel of the "later consequences" for film and paper both. In fact, Haist refers to a minimum acceptable level of HQ for image stability.

One of the reasons a final wash is so long is to remove the HQ from a coating. It is reportedly removed at a slower rate (in general) than Silver Hypo complexes. Of course, this single article is difficult to extrapolate into all real world conditions, but nevertheless, knowing it happens should alert us.

PE

 

[Ian Grant]

We don't disagree about that, the issue was what part a stop bath played in it, and it seems both Kodak & Fuji think none at all as they leave the entire stage out.

My feeling is that potential HQ Metol retention issues are far greater when films and papers are processed mechanically where every stage is kept close to the minimum time limits. Kodak didn't use a stop bath with their RT processing machines either. You pointed out the effects on colour papers in the 70's and this may be another potential issue particularly with wash-less colour film & paper processors.

However as we are talking home processing, or decent monochrome labs then I'd be fairly certain that our stop bath or alternative rinse, longer fixing & washing times will takes us way lower than the Kodak, Fuji RT systems, which they seem to think are good enough.

Ian

 

[Photo Engineer]

The problem is, Ian, all R&D at EK stopped with regard to B&W processes in about 1985 or thereabouts. As the effect of having developing agent retention and thus worse image stability was known but not worked out for home use or even well understood except in color, not much was said about it or done about it. I do know that HQ and Metol are hard to remove and I do know that Metol is rendered more soluble by acid. So, it is harder to remove if you omit a stop and use an alkaline fix. If you use a stop, much of the Metol can be removed in the stop.

As for HQ, it is more easily removed in alkaline solution or if it is Sulfonated, so a Sulfite containing stop can assist in removal of HQ. Thus, I made the statements I did about the utility of stops in general. They can help in this regard.

The current wisdom at Kodak was to keep the current recommendations for use of a stop and if the wash was good enough and had a safety margin, then the film and paper were ok. The problem is that AFAIK Kodak only ran release tests for B&W products in an acid fixer with and without hardener. IDK what Ilford used!

Nowdays, neutral and alkaline fixers are becoming more prevalent. This changes the playing field and I have said that I have no method to test for retained developing agent.

Therefore, I take the route of caution and made the statements I did regarding B&W products because I knew the chemistry involved and the internal test results. Regarding color, neither Metol or HQ is used is used in color and the bleaches are acidic enough. However, in color paper a stop should be used.

PE

 

[Ian Grant]

Research might have stopped Ron but the materials have been around rather a long tome now, silver gelatin negatives nearly 140 years. FP4 is is 55 years old, Tri-X over 70 so if we were going to see problems they'd have occurred by now. That's why I think you're alarmist, fixers contain Sulphite and/or Metabisulphite which aids fixing and removal of silver thiosulphate complexes so HQ & Metol as well.

You make a point about acidity and metol and sulphite all conditions met in Ilford & Kodak's rapid fixers.

So a greater issue arises when someone uses an Alkaline fixer because those criteria aren't being met. I know you advise an acid stop bath but many don't use one so could have major problems particularly with FB prints if what you theorise occurs.

Only yesterday on another forum someone said an acid stop bath was a no no with alkaline fixers. I did say you advised differently.

Then we need to look at just how much developer is adsorbed & used there are figures for how much is taken from solution, and how much is actually used to develop a given area of film. So after a stop bath or rinse we are looking at very low levels left in the film anyway. I have some data on that relating to when Ilford were testing their PQ version of ID-11/D76 (which became Autophen) to determine replenishment rates.

Ian

 

[Sirius Glass]

It is really pretty simple.

Stop bath is cheap and reusable.

If water is used instead of stop bath, the life of hypo is shortened and fogging may occur.

I have used stop bath on film for decades with not problems.

Stop bath should not be used with some developers. Pyro needs an alkaline archival fixer such as TF4 or TF5. Example, Rollo Pyro developer should not have stop bath used because it needs a fixer like TF-4 or TF-5 after a water wash.

Can you use water instead of stop bath for non-pyro developers? Sure, but then again your photographs are probably not worth protecting anyway.

Steve

 

[Ian Grant]

It is really pretty simple.

Stop bath is cheap and reusable.

If water is used instead of stop bath, the life of hypo is shortened and fogging may occur.

No-one has said that except you

Stop bath should not be used with some developers. Pyro needs an alkaline archival fixer such as TF4 or TF5. Example, Rollo Pyro developer should not have stop bath used because it needs a fixer like TF-4 or TF-5 after a water wash.
Steve

You can use a weaker stop bath with Pyro developers and also fixers like Hypam and Ilford & Kodak Rapid fixers. That's what many do including Sandy King

Can you use water instead of stop bath for non-pyro developers? Sure, but then again your photographs are probably not worth protecting anyway.

Steve

You shouldn't talk about your negatives like that Steve

More seriously the use of stop bath with films only began more widely in the 1930's with the big take up of 35mm in Europe.

There's many great negative that never saw a stop bath, it's pure speculative conjecture based on no evidence at all that there could be a difference.

Ian

 

[Sirius Glass]

It is really pretty simple.

Stop bath is cheap and reusable.

If water is used instead of stop bath, the life of hypo is shortened and fogging may occur.

No-one has said that except you

Stop bath is cheap and reusable.

Yes it was earlier in the thread.
See post #11.Stop bath is easy to make. It may be perhaps the easiest photo processing chemical to make with home-found ingredients. Next to water of course. Kitchen or table vinegar (plain, none of the types with herbs or spices added) added 1 part to 4 parts water will make an excellent, reuseable stop bath.
That is why stop bath has indicator in it.

If water is used instead of stop bath, the life of hypo is shortened ...

Yes it was earlier in the thread.
See post #4. "And in spite of opinions it is a chemical reaction."
See post #5. "A stop bath stops development immediately, reduces the risk of staining and will extend the life of the fixer bath. The use of a stop bath is strongly recommended."
See post #7.The main purpose is as stated above that you remove developer before using the ordinary fixer."
see post #11. "I second Fotch in using stopbath. Quickly and positively arresting development (by neutralisation) is better than just slowing it down or weakening it by just rinsing the developer-laden film with water. No worries of getting more development after the film has left the developer. And the fixer lives longer too."
See post #21. "One point that's come up a few times here but deserves clarification is the claim that stop bath can extend the life of fixer. This is true of acid fixers, but not all fixers are acid." And I discussed alkaline fixers.
See post #28. "I also value stop bath's ability to extend the useful life of my fixer."

If water is used instead of stop bath, ... and fogging may occur.

Yes it was earlier in the thread.
See post #32. "Stop bath is the most precise way to immediately arrest development."
See post #81. "You run a much higher risk of dichroic fog staining the emulsion Steve. If the fixers being used one-shot it's also likely to be made up at a lower concentration raising the risk further." Opps that is YOU!*

Steve

* Damn! That has just got to be embarrassing!

 

[Thomas Bertilsson]

 

[Q.G.]

Wait!
Shouldn't you flog (not beat) a dead horse?

 

[Ian Grant]

Should have clarified the fogging bit for you Steve and highlighted the last part of the 3rd sentence, - fogging: that's been pure conjecture, all the companies used water for years with NO issues, and still say you can.

You'll find I've consistently said a stop bath or water rinse will prolong the life of a fixer (stop more so), and that a stop bath arrest development faster

There's been to many unfounded claims based on no facts at all that a water rinse doesn't work properly as a replacement for stop bath, when processing a film.

So no mistakes on my part. I commented on what you wrote, not earlier posts.

Steve Smith was talking using no rinse or stop bath, adding the fix immediately so that comment of mine is out of context when talking about using either water or a stop bath.

One could question your motives for deliberately restirring flames. Ron & I agree that water can be used instead of stop bath.

Ian

 

[Sirius Glass]

So no no mistakes on my part. I commented on what you wrote, not earler posts.

Ian

I do not see your point of your comment. Would you like to explain it in a PM?

Steve

 

[Ian Grant]

I agree Thomas

Ian