Acetic acid as stop bath for film?

[wclark5179]

Agree with Ian.

And may I stick my big nose into the discussion by stating that indicator stop bath is available from many mfgrs. and for the cost per whatever it's pretty dog gone cheap. It has to be if I'm using the stuff!

A bottle of concentrate I've had for years.

Well, I'll quit while I'm ahead and the soap box I'm using is a shoe box and it's starting to cave in!

My recommendation, use the product designed for the job.

 

[hrst]

Surprisingly, I find all these concepts quite simple and clear, even when I haven't done much work around them. I feel that many people are searching for debates and almost religious arguments instead of using their own brain to think a little bit.

For instance; stop bath does not magically remove or clear or delete developing agents. Water does not either. Acid only helps to maintain the pH of fixer. OTOH, two or three rinses, let alone the usually recommended four rinses, dilute the alkali of developer so low that it will not be a problem anymore. We can see that Ilford has a recommendation that 4 wash cycles could be enough even for final wash -- we don't need to believe this completely now, but we can deduce that 4 wash cycles between developer and fixer should really be more than enough - especially because after developer there are no silver-thiosulphate complexes to wash out and the pH is higher, allowing more rapid washing.

Then there's the argument of temperatures. So, you make your stop bath beforehand and let it sit on the shelf, so it's at room temperature. Why in the world can't you do this with water? You need around 1 to 2 liters, not a problem.

Then there's the best argument ever, "false economy", or "don't try to save". This argument is based on a concept that whenever there is any payment involved, the solution must be automatically better. So, stop bath is better than water because you have to pay for it, and you can prove this by saying: "using water is false economy. Stop bath is cheap." A variation of this theme is that stop bath is "designed" for the job. It does not mean that water isn't designed for the job, too. Oh well, water was available before there was film, but so was acid . Anyway, stop bathes are manufactured for two reasons; 1) there are situations where they can be much better than water (but the usual small-tank BW film development with most films and developers is not one of them), 2) there are people out there who want to use it even when it's not necessary.

But, what if using just one stop bath was worse than using 3 or 4 changes of water? I can argue that using just stop bath will result in more than 1000 times higher developer contamination in fixer than 4 changes of water. If I use stop bath, I always use one extra water rinse after it. That means two steps. If I use just water, I use at least three steps. Just one step more. Both need water to be tempered to process temperature. Even just the stop bath does. So is there really something so favorable in stop bath? It does the job, just like water does. Both of them work perfectly!

So, no real difference here. This is a matter of taste. I just really don't find any need for stop bath for film. Your mileage may vary .

 

[Photo Engineer]

Falsehoods?

Consider that Metol is an organic base. It is sold as an acid salt and is difficult to dissolve in high concentrations in alkali.

A stop bath helps by acidifying and making Metol more soluble and removing it from the coating. Extending wash and / or using a neutral or alkaline fix helps remove HQ which is an organic acid and is soluble in base more than acid. The permissible retaine levels of HQ are reported by Haist, but IDK any reports on retained Metol levels. Also, the reaction of Sulfite used in some stops and all fix baths and developers help deactivate HQ.

As for posting information that is incorrect on the internet, with us losing photographic engineers, it behooves one to try to get the correct information out there. I posted the reference to Haist before. If anyone can prove me wrong either by reference or chemical knowledge, please do so!

Since I used a reputable literature reference regarding permissable retained HQ levels, I respectfully request that Ian edit or remove his post.

PE

 

[Ian Grant]

Falsehoods?

Consider that Metol is an organic base. It is sold as an acid salt and is difficult to dissolve in high concentrations in alkali.

A stop bath helps by acidifying and making Metol more soluble and removing it from the coating. Extending wash and / or using a neutral or alkaline fix helps remove HQ which is an organic acid and is soluble in base more than acid. The permissible retaine levels of HQ are reported by Haist, but IDK any reports on retained Metol levels. Also, the reaction of Sulfite used in some stops and all fix baths and developers help deactivate HQ.

As for posting information that is incorrect on the internet, with us losing photographic engineers, it behooves one to try to get the correct information out there. I posted the reference to Haist before. If anyone can prove me wrong either by reference or chemical knowledge, please do so!

Since I used a reputable literature reference regarding permissable retained HQ levels, I respectfully request that Ian edit or remove his post.

PE

I'll leave my post it's time people began to realise the mis-truths.

Your argument is with Kodak not me they STILL recommend a water rinse as an alternative to a stop bath with film as they have done for over 100 years, as do Ilford. If you don't agree with Kodak tell them get them to clarify here on APUG.

If people want to read the reams of previous mis-information just search Photonet.

Meanwhile please stop posting your speculations that are contrary to all published data and working methods as well as best practice of all the major companies including Kodak. They will only be valid if an unbiased third party and then others can verify them.

Ian

 

[hrst]

So, acid stop bath is better for removing metol, and water bath could be better to remove HQ? And then, we have a lot of other dev. agents, everyone being different beast.

My point is; if we go deep into details, this is getting more and more complicated. But, as everyone knows, both acid stop bath and water works great for normal BW film and both must be used correctly.

I think that as a subject of discussion stop bath is not the most interesting one .

 

[alanrockwood]

I can't find the solubility of 4-aminophenol at neutral pH. However, the solubility of two related compounds are as follows: analine (3.6 g/100 mL at 20°C) and phenol (8.3 g/100 ml (20 °C)). Each of the two related compounds have one polar group, which aids in solubility. 4-aminophenol has two polar group, one being a phenol, and the second being an amine. One should therefore expect it to be at least as soluble as the related compounds that only contain one polar group. Therefore, unless there is some very strange chemistry going on (highly unlikely) 4-aminophenol should have a solubility in the range of several grams per 100mL, if not higher. This means that solubility is not likely a limiting factor in film removing metol from film.

There are some additional subtleties one might consider, such as partition coefficients of metol between gelatin and water, but I won't attempt to get into that topic at the moment.

 

[Photo Engineer]

Ian, Alan;

In the Kodak darkroom dataguide for prints and film, on P54, dated 2002, they do not even mention rinses for papers, only stops! On page 16, for film, they again do not mention rinses. On page 30, they repeat the data from the page 16 table in words not mentioning a rinse. I agree that in some data sheets they say that a running water rinse can be used instead of a stop. But, their usage is clear. They prefer a stop. Here: http://www.ilfordphoto.com/Webfiles/20062101959492766.pdf Ilford says stop! This is one of the examples where both are mentioned, but note the header on that paragraph. It does not say "rinse".

I have posted the Kodak paper data sheet here in an earlier post for your information. I will be happy to post the Kodak film data sheet as well. But, what is there about posting actual data sheets that strikes you as being an untruth or a half truth.

As for HQ being retained, Haist on P204 VII, discusses and shows the retention of HQ in film as being about the same as Hypo in an all alkaline environment (Monobath) and warns about HQ retention as being a problem, especially with short wash times with alkaline fixes and monobaths. Washing is so fast under these circumstances that you can test correctly for retained fixer and silver but still have retained HQ. See A. Green and M. G. Rumens, J. Phot. Sci. 19:149-150 (1971). I believe that there are now ANSI standards for retained HQ, Metol, Hypo and Silver in processed materials.

Wash times differ from solubility data due to diffusion and the action of gelatin notwithstanding "proofs" from handbook data.

PE

 

[alanrockwood]

PE, actually, the Ilford document you linked recommends either water or acid stop. Here are the exact words in their entirety.

"After development, rinse the film in water or an acid stop bath (Ilford IN-1). IN-1 stop bath stops development immediately and helps maintain the correct pH of the fixing bath."

Strictly speaking it does not even recommend one over the other.

It does say that an acid stop bath stops development immediately, which is true, but this does not necessarily mean that stopping the development process immediately produces a superior result. In fact, as you well know, a slight shortening of the development step when using a water stop bath would compensate for that small difference.

It also says that an acid stop bath would help maintain the pH of the fixer. This may prolong the lifetime of the fixer, which may imply a (small) cost savings because the fixer would last a little longer, but this implies nothing about the quality of the processing itself. Actually, this is likely to be a very small effect anyway. A water rinse will remove the vast majority of the alkalinity (likely of the order of 99% or more), and the water itself would have no effect on the fixer other than dilution, and even this dilution would likely be a small effect unless there were substantial carryover of water.

By the way, I am confining my comments to the scope of the original question, i.e. film.

 

[Photo Engineer]

I acknowledged the two recommendations in the Ilford document in my post above. The priority was given to the words "Stop". In addition, you may wish to look here: http://www.ilfordphoto.com/Webfiles/200621111052496.pdf This document, which discusses paper processing, states that use of a stop will reduce the risk of staining. The Kodak references I gave and posted all refer only to use of a Stop even though there are references to both in some Kodak publications as well.

Oh, BTW, Ilford suggests running water for washing paper! See page 2 of my reference in this post for all of the

Remember the old saying about mixing a developer? Add a pinch of Sulfite, then the Metol (which is a Sulfate salt of an organic base) and then add the rest of the ingredients. The Metol is difficult to dissolve in alkali and easier to dissolve in acid or neutral solutions. This same reasoning applies to the use of a stop when you use a Metol containing developer.

In addition, the use of an all alkaline process makes the wash cycle so brief that HQ diffusion outward becomes the rate determining step in achieving an archival process. A stop does not influence the removal of HQ except to slow it down if anything. Therefore it is more probable that any loss in archival properties of anything processed in an all alkaline process will occur due to retained HQ rather than retained Silver or Hypo.

PE

 

[Photo Engineer]

For those interested

Yesterday, I posted Kodak instructions for paper processing.

Due to some claims, I have decided to post the Kodak film processing instructions taken also from the 2002 B&W manual published by Kodak.

These recommendations clarify that Kodak suggests a Stop Bath for film and paper at the present time. They also include two options for wash as I noted before.

Please not that there is no hand waving or accusations here. I have merely posted published documentation by Kodak.

PE

 

[Q.G.]

And to get the complete picture, out of how many Kodak documents, how many did you find that only mention a stop bath?
(And remember, we're talking about film here.)

And how many say, or even imply, that you must use a stop bath, and cannot use a water wash?

 

[Photo Engineer]

Searching Kodak documents regarding film, I found 5 that mention both a water rinse with Stop Bath being listed first. I found 3 with only Stop Bath listed and no other options, and one with only water listed. Regarding paper, I found 2 that mentioned only Stop Bath with no other options. I have 2 text books that list both methods.

For Ilford, all film publications list both for film but only a Stop Bath is recommended for paper.

The comments, but not the exact numbers were posted by me in all cases above. I acknowledge that both have been suggested for films and I have stated that in the above posts where I referred to Ilford and Kodak web sites. However, the preponderant evidence seems to be that the manufacturers support the use of a Stop for both film and paper, and allow that running water can be used if one wishes for film. I have yet to find a reference to using only a rinse with paper. I have tried it and have had problems.

I would like to add that in all cases, the literature says that staining can result if a Stop Bath is not used. I have offered reasons for one possible mechanism for this based on Haist. I have not listed derivative texts or references to the above as they refer, in most cases, to the above.

PE

 

[Q.G.]

Seems to me then that manufacturers have no trouble with either method.

Personally, i believe rightly so: for all i know, both methods work absolutely fine (i did use stop bath for film when i first started processing my own, but have been using water for longer than i can remember.) And i wouldn't know how or why to advise against any one of the two.

I believe (there is so much discussion about this, that i begin to lose track ) i have read your explanation about the potential for staining. And i wouldn't know anything that would not be correct about that explanation.
Yet i have never seen any of it (staining, that is). Maybe i haven't given it long enough.

 

[Photo Engineer]

Well, since that last post of mine, I have found 3 more text books that follow that line of thought as well as one Journal. They all say one or the other or either. Interestingly enough, one of them suggests using a water rinse and then a Stop Bath. So, these authors suggest both. The references I found were Eaton, Jacobsen and the jointly published Jacobson and Jacobson.

If I rank order them for date, the oldest Kodak references recommend water, and the most modern recommend Stop Baths or a running water rinse for film, but again, they all agree on Stop Baths for paper.

I have some RC and FB paper wash series here, but I hesitate to post them due to the fact that I used an experimental fix (SF VIII) for the tests, but basically I do see profound yellowing at short wash times and decreasing yellowing as wash times increase. The yellowing has taken up to 5 years to appear depending on wash times.

One thing that is present in most texts is the warning of stain without a stop.

PE

 

[Q.G.]

Let's not vere off the "film" track every so often, but stick with the thread title and forget about paper?

 

[Photo Engineer]

I agree and it is another reason not to post my samples. With film though, the stain is difficult to see. I have never tried scanning the film though and I have disposed of them by now.

PE

 

[Ian Grant]

Let's not forget the stain reported by some users if you use an Alkaline fixer with films, it's called Dichroic fog, and it DOES sometimes occur.

It's interesting that NO film manufacturer recommends an Alkaline fixer with B&W films, dichoic fog is unimportant with colour, C41 or E6, as the silver image is dissolved away anyway.

Ron, you know full well that Kodak are still recommending a Stop bath OR a water rinse in later & current datasheets since 2002 so PLEASE stop the bull-shit once and for all, all it does is increase our doubts in your statements. I've posted the Kodak links many times now AND you've acknowledged them, and accepted them in a previous thread.

I can post where you've said you accept that Kodak say's a water rinse is fine, if you can't remember.

This posturing like a Kodak Cockrel is getting rather tedious now, and needs to stop. I no longer trust anything you say or post.

Ian

 

[Photo Engineer]

Ian;

I have posted data sheets from Kodak Dataguides here for both film and paper that prove what I said and which is summarized in the post above. I have posted references to Kodak and Ilford PDF files that are also summarized above. I like and use Ilford B&W products so your statements are kind of off the mark for me.

I do accept that Kodak says that a running water rinse is fine for film, but we cannot ignore that in the same paragraph they recommend a Stop Bath too. And, I cannot dismiss their Dataguides. I also cannot dismiss the same comments from Ilford!

I have never seen any dichroic fog from any process of mine (an effect which is more normally associated with silver halide solvents in developers as you well know), nor has anyone else I know gotten any dichroic fog, and you yourself have said that modern films are quite resistant to this problem. So, I really don't know what your problem is other than accepting the documents and that there is a plurality of methods given by both major companies with some inconsistencies and some preferred methods expressed for given products.

I would have posted data from Fuji as well, but I cannot seem to find relevant data on their web site.

PE

 

[hrst]

You are arguing about quite small nuances... . It seems that everyone accepts that for film, BOTH are accepted methods. In some instructions, only one of them is mentioned, in some instructions they are in different order than in others.

 

[Photo Engineer]

Maybe so and maybe not. It is for the user to determine based on results. It also is something that has evolved over time as the nature of films has changed somewhat leading to mixes of old and new concepts.

50 years ago or more, soft films were the norm and some were afraid of Carbon Dioxide bubbles forming in film. Harder films solved this. But, I remember using an old Pako dip and dunk machine in the '50s that used a Stop Bath and an acid Hardening Fixer. I've just been re-reading portions of Mason on Stops and Fixes and he is also ambivalent suggesting a prewet, a rinse after development and then goes on to give reasons why a Stop should be used.

After the last of the analog system engineers are gone, you guys are on your own. Figure it out yourselves. But, this back and forth is why I stated earlier that it I am becoming less and less inclined to participate in threads like this. I have been encouraged by others to continue. Maybe they like to see this type of back and forth. IDK. I'm still debating. I have not posted on the other Stop thread.

PE

 

[hrst]

PE,

I really don't want to sound arrogant, but I think that you could use your time better in discussing emulsion work! Or to rephrase, I think your skills are much more than just stop baths! (I'll post soon about my development with the emulsion making pump system. It has seen much progress over last few weeks.)

All the best.

 

[Sean]

I think when it comes to traditional photography there is usually more than one way to skin a cat. I like to see debate and different views, but I don't like when things take that turn into a "pissing contest" and endless battle. I'm not directly accusing anyone here but really, we are all in this together and all lose out when these battles sour the tone around here.

 

[Photo Engineer]

You are hardly being arrogant.

And, I just cannot do one thing all the time. Variety is the spice of life. Process chemistry was a core portion of my work for nearly 10 years and so I am really in to it!

Besides, as you may be aware, I get criticized for my statements on emulsion work as well. So, it really does not matter where or what I post. It does strike me though that my strongest critics have never posted a single original emulsion formula, an original coating result or an original process formula such as a fixer or a developer!

Thanks for your comments though. I am looking forward to your latest work.

PE

 

[lajolla]

Sean, I am not a big fan of your 'skin the cat' analogy. Poor choice of words, and also in the case of this meticulously drawn-out thread, not really helpful. I have just finished reading the entire thread, and I am astonished at the unconcealed ill-will displayed toward Photo Engineer by some of the participants. PE has been providing incredibly accurate info on this forum for a longtime. If someone doesn't happen to agree with PE, of course that is life in the big city, but one should never, ever, question his expertise.

 

[Ray Rogers]

The debate in the latrine over "Holy Water"

I too, wish the phrase would go away.

It describes a CATastrophe!

(Perhaps more for tiger than for tabby)
---
I cannot believe this "debate" continues!
---
One should not feel compelled to
correct every instance of photographic heresy...
believe everything anyone says...
nor
refer to sincere, on topic posts as fecal matter....
---


On the brite side,
better bullshit than steer or oxen poop!