Alkali-stop. Is it myth?

[Usagi]

There are lot of rumours and internet discussions about alkaline stop baths. But still I am not sure is alkaline stop bath really true and reliable choice to use instead of water stop when using tanning developers (such as Pyrocat-HD and DiXactol).

There is one alkaline stop available (or it's only that I know), http://www.monochromephotography.com/stopbath.htm

I have tested this, but does it really do something that pure water does not? I really don't know.
I must admit, that I am bit sceptic about whole thing.

 

[PhotoJim]

I guess you can say I'm in the category of those not seeing the point. Actually stopping development precisely is not that significant, unless your development time is very, very short.

I've used a running water stop for years and it works fine for me. I suppose there is a tiny bit of development happening until the film is fully fixed, but who cares? The effect is so slight that I don't care, and I'm choosing my development time based on the final results of past rolls anyway.

 

[Photo Engineer]

An alkaline stop bath is very very difficult to design. It can be done, but to what purpose?

I've made neutral and slightly acidic stop baths as well. The problem is that they often interfere with fixing. This is the real problem.

PE

 

[Michel Hardy-Vallée]

I've emailed the fella at Monchromephotography to have some insight on his product, but he would not produce an MSDS, because they are apprently not mandatory in his legislation.

Maybe he succeeded in doing what no other photochemist could do: sell tap water to unsuspecting clients...

 

[David A. Goldfarb]

I don't develop by inspection, but if I did, that's one reason to use a stop, since you might be processing several sheets of film in a batch, and you may want to hold sheets in the stop for several minutes before transferring all the sheets to the fixer at once.

 

[Ian Grant]

I've emailed the fella at Monchromephotography to have some insight on his product, but he would not produce an MSDS, because they are apprently not mandatory in his legislation.

Maybe he succeeded in doing what no other photochemist could do: sell tap water to unsuspecting clients...

Most likely if he told you what's in it you'd make your own up for a very small fraction of the cost

There may be unexpected benefits from using a Citric acid/Sodium Citrate buffered stop bath, Japanese photo-chemists (at Fuji) discovered that Citric acid and Tartaric acid and their salts improve fixing times while acetic acid doesn't. Traditional fixers needed to be acidic because the Potassium Alum hardener doesn't work properly in neutral or alkaline conditions, and in the past films weren't pre-hardened like the vast majority of modern films.

An alkaline stop bath may in fact be very close to a neutral pH, certainly one Kodak Patent (USP 3284199) cites a pH of 7.2

Ian

 

[Dave Miller]

There are lot of rumours and internet discussions about alkaline stop baths. But still I am not sure is alkaline stop bath really true and reliable choice to use instead of water stop when using tanning developers (such as Pyrocat-HD and DiXactol).

There is one alkaline stop available (or it's only that I know), http://www.monochromephotography.com/stopbath.htm

I have tested this, but does it really do something that pure water does not? I really don't know.
I must admit, that I am bit sceptic about whole thing.

No, it doesn't do anything that water (pure or otherwise) will do as far as I know. If you read the manufacturers developer or fixer instructions they state that the same effect is obtainable by several rinses in water. So, the choice is yours; as ever. I use it when developing film, but not prints, when I use several water rinses.

 

[Photo Engineer]

I don't develop by inspection, but if I did, that's one reason to use a stop, since you might be processing several sheets of film in a batch, and you may want to hold sheets in the stop for several minutes before transferring all the sheets to the fixer at once.

David;

The problem with an alkaline stop is usually that when it does its stopping action, you most likely cannot get development started again, or if you do, the development is skewed in tone, curve or some other factor.

This is the real problem. Once you stop, it wants to stay stopped, and if you carry stop back into the developer, then the developer becomes a stop as well. Carryback with an alkaline stop is quite detrimental in most cases.

PE

 

[David A. Goldfarb]

I wasn't implying that you would want to start development again, but say you had 8 sheets and decided by inspection that four were done at 8 minutes, and two more were done at 10 minutes, and one more at 15 minutes and one at 20 minutes, you wouldn't want the completed sheets to be sitting in a water bath developing slowly while waiting for the last ones to finish, and you wouldn't want to get your hands in the fixer while you were still shuffling sheets in the developer tray, so that would be a case where it would be more beneficial to use a stop (either acid or alkaline) rather than a water bath.

 

[Photo Engineer]

In that case, I can give you a simple formula, but carryback is going to be as much a problem here as if you went right into the fix after a wash. Remember, touching this solution is not good either. It is like getting your hands into the fixer in its own way.

PE

 

[Michel Hardy-Vallée]

Most likely if he told you what's in it you'd make your own up for a very small fraction of the cost

Yeah, I tried. :rolleyes:

 

[Snapshot]

The Film Developing Cookbook (by Anchell and Troop) propose a couple of experimental base formulas for alkaline stop baths.

 

[Snapshot]

A slight correction to my previous post regarding the formulas. They don't have specific formulas per se but Anchell and Troop propose the following start points:

A solution of 5% to 10% potassium bromide combined with a solution of 2% to 5% sodium sulfite. In addition, they advise the use of a buffering system to keep the pH between 8.5 and 10. They recommend a combination of sodium metaborate and sodium bisulfite for this. You can substitute the potassium bromide for 0.5% to 1% benzotriazole or 0.05% to 0.1% of 1-phenyl-5-mercaptotetrazole.

So, I suppose you could start with...

Water........................750ml
Potassium Bromide........100g
Sodium Sulfite..............50g
Sodium Metaborate.......15g
Sodium Bisulfite............10g
Water to make.............1000ml

Obviously, you can play around with this to get the desired pH. I, however, have not tried to use a alkaline stop bath and cannot confirm if it would work reliably.

 

[sanking]

The interest in alkaline stop baths appears to stem from some research, and more speculation, that indicates certain advantages to taking film through an all-alkaline environment in processing, from the developer through fixing. Thus the recommendations for water stop baths and alkaline fixers.

This seems like more theory than fact to me. And if it is true, how could you ever prove it?

My only concession to this type of thinking is that after development I usually transfer the film to a water bath for a couple of minutes -- the thinking being that exhaustion of the developer may favor the creation of more adjacency effects. But if you asked me to prove this I never could. After the short stop bath in water I run the film through a regulr acid stop bath on its way to the fixer.

Sandy King

 

[Ian Grant]

Sandy, does that mean after Pyrocat you use an acid stop-bath then an alkaline fixer.

The pH of Ilford Hypam or Rapid fixer is around 5 to 5.5 which is far less acidic than an acetic or citric acid stopbath. Ilford's Ilfostop or Ilfostop Pro have a pH of 1. Can we assume that using a Fixer like Hypam will have little or no detrimental effects on the Pyrocat stain ? . . and that an alkaline fixer is unnecessary ?

The only fixer I currently use is Hypam (or Ilford Rapid fix) and I've been getting good staining with Pyrocat, but I'm assuming that old fashioned acid fixers are/were far more acidic

Ian

 

[sanking]

Sandy, does that mean after Pyrocat you use an acid stop-bath then an alkaline fixer.

Ian

Ian,

I use an alkaline fixer after the acid stop bath. However, I also think it is pefectly fine to use a mildy acidic fixer of pH around 5.5 rather than an alkaline one with Pyrocat-HD or -MC. I did some comparison tests of this a couple of years ago and the intensity of the proportional stain was almost exactly the same with the alkaline and acidic fix.

Sandy King

 

[dancqu]

Developer - Water Stop - Acid Stop - Acid Fixer

An Eddie Ephraums suggestion.
He may have had ph shock and
reticulation in mind. Dan

 

[Usagi]

Thanks for everyone. This thread has given very much information to me.
I will use water stop bath from now, it seems to be safe choice.

That is very interesting that acidic fix does not have much effect on proportional stain. It makes me wonder where all recommendations for alkaline fixers came from?

 

[PhotoJim]

Alkaline fixers was out of film and paper faster than acid fixers do. There is also a difference in the amount of stain, although many workers feel that the difference is not significant.

 

[Dave Miller]

That's correct Jim, it's the shorter washing times that attracted me to the use of an alkaline fixer. Simply because I am on a metered water supply and have to pay for it's delivery and disposal.

 

[Philippe-Georges]

This is what AGFA told me years ago :

 

[Photo Engineer]

Sulfites work as stop baths in color processes because they interact instantly with oxidized color developing agents and stop further development. This is not the case in B&W processing. The main reason why sulfite would work in B&W is due to the acidity.

PE

 

[pentaxuser]

That's correct Jim, it's the shorter washing times that attracted me to the use of an alkaline fixer. Simply because I am on a metered water supply and have to pay for it's delivery and disposal.

Dave very shortly all of us in the U.K. and most of us now are/will be on metered water. Certainly I have been for a number of years. Presumably the real benefit comes with FB paper where water usage can be significant. As I recall things, the water wash with RC is very short and I assume that with RC the wash time is at or near an irreducible minimum such that a switch to alkali fixer for RC prints would make little or no difference to water consumption. Am I right?

As a matter of interest have you worked out, even roughly, the water saving with alkali fixer for printing? For instance to give a "handle" on the change in consumption let's assume the Ilford routine of 5 mins wash, 10 mins Washaid and 5 mins wash. What is likely to be the saving in washing time here? Maybe better still, what were the changes to your routine since converting to alkali fixer. Thanks

pentaxuser

 

[Photo Engineer]

Just FYI, I am in the final stages of development of a new fix which should further reduce fix time and wash time for film and paper. I understand this problem.

PE

 

[Philippe-Georges]

Just FYI, I am in the final stages of development of a new fix which should further reduce fix time and wash time for film and paper. I understand this problem.

PE

Dear PE,
This is wonderful!!