Stop Bath.. How important?

[Ian Grant]

Fuji Acros spec sheet:

"For the stop bath a 1.5 % acetic acid solution is recommended. Immerse the film in the bath at 15 to 25°C (59 to 77°F) for 20 to 30 seconds while agitating."

Fuji also use no rinse or stop bath at all between Development & Fixing in machine processing of Acros so I guess they are saying what Mason says a stop or rinse is superfluous

The real purpose of a stop bath with B&W lims is to extend the life of a fixer, it's that simple, yes it also stops development faster than a water rinse which is a bonus.

Ian

 

[Q.G.]

Fuji Acros spec sheet:

"For the stop bath a 1.5 % acetic acid solution is recommended. Immerse the film in the bath at 15 to 25°C (59 to 77°F) for 20 to 30 seconds while agitating."

That's a recommendation telling how the stop bath should be. If you use one.


I think it's a big-endian vs little-endian thing. Much ado about nothing, and all that.

I have never come across any ill-effects of not using stop, rinsing with water instead. But that does not necessarily mean the reasoning behind the stop recommendation is flawed. The fact that something hasn't happened yet doesn't necessarily mean it will never or can't ever.

Yet i do believe too that Ian makes a good point and puts it across equally well. Haven't read anything that would/could prove him wrong.

So the conclusion i draw for myself is that i continue doing what i have (almost) always done.

 

[Thomas Bertilsson]

I just wanted to get at Ian's BS comment. Kodak says, Ilford says, Fuji says... I figure this will never be settled, so I'll just keep doing what I was doing before. Too many chefs to make this soup any good.

 

[Ian Grant]

I just wanted to get at Ian's BS comment. Kodak says, Ilford says, Fuji says... I figure this will never be settled, so I'll just keep doing what I was doing before. Too many chefs to make this soup any good.

Thomas, I'll keep doing what I've always done, which is mostly use a stop bath with films, and when I don't I give a better rinse/soak than both Ilford or Kodak suggest, as I use an older Inversion Jobo 2000 tank that's plenty of water

For me it's settled it's in writing from the film manufacturers and Photochemistry books. It's not my data it's the leading Photochemists.

You need a rather strong set of entirely new research data to even begin contradict Kodak, Ilford & Fuji's recommendations.

Any thing else is Bull shit based on pulling wild assumptions and theories from thin air.

In this entire thread I've only stated what the major ompanies have recommended over rather a long period of time at least 100 years, and even today they HAVE NOT changed those recommendations.

Ian

 

[Photo Engineer]

The only flaw here is that stop bath doesn't remove all the residual developer, it doesn't have time to.

No, but it helps in making Metol and HQ more soluble in the fixer.

Usually the recommend stop bath times are short 10 seconds is one manufacturers suggestion.

So a 1 or 2 minute rinse might actually have a greater effect on removing developer from the emulsion.

The fact that a stop bath is even mentioned by a manufacturer shows that they take notice of them and do suggest their use.

In nearly 140 years of Gelatin film emulsions there's never been a theory or evidence that residual developer has lead to any deterioration of a negative, despite the fact that Ilford, Agfa, Kodak and others didn't recommend a stop bath with many films & plates.

There are a lot of things never mentioned in the literature that were not considered important. Image stability was not mentioned at all until the 80s when Henry Wilhelm brought the subject up and pollutants as contributors to image deterioration is a rather new concept.

In addition they were suggesting a rinse in water after development in highly active developers, with dev times of 2-4 minutes which rather seems to indicate that statements 1 & 3 are rather unlikely scenarios given that most of us develop now in far more dilute modern developers.

Paper developers are used at 1 - 4 minutes IIRC. Don't forget them!

Ron's comment about a problem with a 1970 colour paper clearly indicates that carry over with FB papers is a far greater problem due to the dev that's soaked into the paper itself. RC Colour papers came in slightly later.

Oops, you goofed Ian. Ektacolor 30 and 37 papers were RC based, as was the predecessor, Ektacolor 20 which was out in the early 60s.

Food for thought this is what KODAK currently say with film developing

We can assume Kodak know best, which is what Mason (Ilford) & by default Levenson (Kodak) said as well mid 70's

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 so lets cut the Bull-shit, that's in the current Tmax data sheet, and in other film data sheets as well.

Ian

Yep, Kodak says Stop Bath or Running Water. Note that the Stop is mentioned first.

If you run a good process even with a rinse, you will remove all traces of developing agents from the coating if the film or paper tests ok with the normal hypo and silver test kits. But then, not everyone is so diligent in their processing!

Now, as to BS Ian, Everyone, please read what Mason actually says... He says that "an acid stop bath is desirable". Please do not extract "quotes" from someone to just suit your purpose. Here is the whole passage in question.

PE

 

[JBrunner]

Keep in mind that those who recommend stop also sell it. As I said before, I cannot personally recommend one over the other, except as a personal preference, and that I have had no ill effects with water. I do, however, run a pretty tight process. I would say that someone who is sloppy might be better off using an acid stop.

 

[Thomas Bertilsson]

Are you saying my process is sloppy, Jason?

Keep in mind that those who recommend stop also sell it. As I said before, I cannot personally recommend one over the other, except as a personal preference, and that I have had no ill effects with water. I do, however, run a pretty tight process. I would say that someone who is sloppy might be better off using an acid stop.

 

[JBrunner]

Are you saying my process is sloppy, Jason?

Yes, it's evident in that wonderful print I have of yours that I see every-time I leave or enter the house.

 

[Photo Engineer]

Developing Printing and Enlarging

This is a scan of a page from one of the early photo books from Kodak. It describes developing Film, making contact prints and making enlargements.

In it, they describe the best methods to process and wash films and papers.

Take a look at the middle tray and consider the implications in the face of the supposed BS. This shows that Kodak was teaching the use of a stop bath as far back as the 40s. The book is not clearly dated but implies a print date in 1947. I certainly had this book in 1950.

PE

 

[Photo Engineer]

Yes, Kodak and others sell stop baths, but you can use white vinegar!

PE

 

[Ian Grant]

Note Mason's words in the third paragraph;

THIS STOP BATH IS SUPERFLUOUS when talkingg about fixers like Hypam & Ilford & Kodak Rapid Fixer. Most people use this type of fixer, only a very small percentage use Neutral or Alkaline fixers. none of the reputable large manufacturers make them for B&W film/paper use.

None of it gets away from the fact that the film manufacturers say water is OK instead of Stop bath which is the whole point of this thread, and we can't contradict what the manufacturers say

Ian

 

[Photo Engineer]

Ian;

Read the whole paragraph. There is a "BUT" in that sentence and he goes on to say something else by the end of the paragraph! And, look at the photo in my last post.

PE

 

[Ian Grant]

In many posts in this thread I've addressed that but, the extended fixer life so that's a another crass comment.

Ian;

Read the whole paragraph. There is a "BUT" in that sentence and he goes on to say something else by the end of the paragraph! And, look at the photo in my last post.

PE

This is what I mean you deliberately post paper processing images when we are talking about film.

It's completely irrelevant.

No-one is saying that for optimum fixer life a stop bath doesn't need to be used. Rather that water can also be used if you want.

So you read the Kodak data, YOU CAN'T DISAGREE, you accepted it in the other post and you still argue with the facts.

Ian

This is a scan of a page from one of the early photo books from Kodak. It describes developing Film, making contact prints and making enlargements.

In it, they describe the best methods to process and wash films and papers.

Take a look at the middle tray and consider the implications in the face of the supposed BS. This shows that Kodak was teaching the use of a stop bath as far back as the 40s. The book is not clearly dated but implies a print date in 1947. I certainly had this book in 1950.

PE

 

[Photo Engineer]

Pages from 2 more Kodak publications on processing. And, in these they specifically mention film and also bring up calcium sludge which is a problem with some hard water supplies.

PE

 

[Ian Grant]

It now makes ZERO difference what else you post Ron about this in this thread, Kodak themselves say right now that you can use a water rinse for films, instead of stop bath, so cut the one-upmanship you're not arguing with me rather the data a company you once worked for until you retired has published.

Kodak publish the data, If you don't or can't agree with it take it up with them directly, it's not relevant to APUG.

Ian

 

[Photo Engineer]

And here is Haist on Stop Baths. He mentions both film and paper. And consequences of not properly stopping development. Please note what he says of a water rinse!

In actual fact, manufacturers recommendations have not changed. They have recommended a stop as did Mason and Haist if you read my posts carefully. They say it is mandatory for paper and recommended for film but you can use a water rinse for film if you must. Then all 3 sources, EK, Haist and Mason list some of the consequences of not using a stop bath.

From your post #108:

"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."

Fuji and Ilford state much the same.

So they all published similar data and Mason and Haist along with Kodak data books agree. A stop is strongly recommended but a rinse can be used with film. A stop is not recommended with paper!

PE

 

[Ian Grant]

I TOLD you whatever else you add or say is totally irrelevant and yet again it is, yes they have recommended a stop bath, and then ALSO said you can use a water rinse instead (talking about films).

You KEEP contradicting Kodak's own current data. I guess you just can't be bothered to read what Kodak actually say in the Tmax Data-sheet and accept they may know a bit more than you.

Take that up with them not me. It's KODAK'S suggestions & methodology not mine, I just use it sometimes and it works.

Ian

And here is Haist on Stop Baths. He mentions both film and paper. And consequences of not properly stopping development. Please note what he says of a water rinse!

In actual fact, manufacturers recommendations have not changed. They have recommended a stop as did Mason and Haist if you read my posts carefully. They say it is mandatory for paper and recommended for film but you can use a water rinse for film if you must. Then all 3 sources, EK, Haist and Mason list some of the consequences of not using a stop bath.

From your post #108:

"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."

Fuji and Ilford state much the same.

So they all published similar data and Mason and Haist along with Kodak data books agree. A stop is strongly recommended but a rinse can be used with film. A stop is not recommended with paper!

PE

 

[Photo Engineer]

Ian;

I'm sorry that you keep misreading those posts of mine and others who posted instructions from Fuji for example. I did not misquote them. I even posted some of them.

They all say Stop or Rinse for film and Stop for paper. The texts go on to state that a Rinse with film may cause problems and they enumerate those problems. What more can I say?

In the case of HQ and Metol washing out of films and papers, Haist has a small bit on this in the Monobath chapter referring to work on the removal of Hypo vs HQ from film during washing. He shows in the data he used, that HQ washes out more slowly than Hypo and the Silver complexes. It also uses 12 deg C wash water, which is cold.

BTW, the level for archival quality of HQ vs Hypo is also shown. Reference: A. Green and M. G. Rumens, J. Phot. Sci., 19:149 - 150 (1971). And this work was on Monobaths, but, as I mentioned above, I have seen similar work on normal B&W and color processes.

There are other studies, but I cannot locate any publications, just this reference which is related to Monobaths. But it does clearly show limits to HQ for archival keeping and this is well known for all developing agents.

PE

 

[lensmagic]

PE, I again commend your patience and diplomacy. Does this forum have a moderator? Is he sound asleep? pk

 

[Photo Engineer]

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

 

[alanrockwood]

Alan;

Again, you misunderstand. In the diffusion of ions through gelatin, Hydrogen is the fastest and Hydroxide is second in rate, therefore you have an inrush of Hydrogen meeting Hydroxide and a wavefront of neutral water forming as the Hydrogen diffuses downward and Hydroxide moves upwards. When the wavefront reaches the bottom of the coating (or in our tests the undercoat with indicator dye), you stop the reaction. This is virtually instantaneous.

There is a tiny gradient in charge which appears to be taken up by a shift in the equilibrium of the overall medium. Diffusion of Sodium and Acetate for example take place at only a slightly lower rate due to size and this is partly overcome by both shifts in equlibria and in the slight charge imbalance (if any) which takes place. Overall, in the average coating, all diffusion is done in about 15" or less, but the neutralization appears to take place in less than 5".

The two major researchers at Kodak on this were Liang and Tong. They developed a diffusion model for water, hydroxide, acid, dyes and other chemicals through emulsions.

One experiment had the acid anion and proton anchored in place through polymerization of the anionic portion of the acid molecule. They then showed the rapid diffusion of hydroxide into the acid layer to neutralize the alkali. Or, conversely, the proton (hydrogen ion) diffused upwards into the alkaline medium. This led to the development of proper barrier layers in instant products BTW and showed how diffusion and neutralization took place in coatings when acid and base were both present. This "timing layer" was crucial due to the rapid diffusion of either Hydrogen ion or Hydroxide ion. They had to be held back from each other while the development took place and the dyes diffused.

PE

OK. Let me be sure I understand what it is that you are suggesting. Once that is crystal clear then we can discuss the implications.

What I thought I understood you to say is that hydrogen ions move from the solution into the emulsion in a fast inrush by process of diffusion. While this very fast process is occurring the other ions don't move much because their diffusion coefficients are much less than the diffusion coefficient of hydrogen ions. Then the other ions diffuse more slowly until everything is equilibrated. It is as if the hydrogen ions are running, and the other ions are walking, so the hydrogen ions leave the others far behind.

In this scheme hydroxide ions are a partial exception to this description. They also undergo a fast diffusion, but not as fast as hydrogen ions, and these two types of ions diffuse in opposite directions.

Along the way, as the inrushing hydrogen ions meet the outrushing hydroxide ions these two species combine to form water molecules.

Is this a fair description of what you are saying?

 

[Photo Engineer]

Yes, it is so, but an approximation. It takes place over less than 15" at 68 deg F.

PE.

 

[Ray Rogers]

A stop is not recommended with paper!
PE

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.

 

[clayne]

Sometimes Ian just goes on the warpath and won't listen to anything but what he wants to hear. It can be maddening at times.

Anyways I use stop-bath with films. I even reuse it. Never had any issues. No pinholes, none of that paranoid nonsense.

 

[alanrockwood]

Yes, it is so, but an approximation. It takes place over less than 15" at 68 deg F.

PE.

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.