Okay, how does alkaline stop bath actually work?

Raghu Kuvempunagar · Sep 21, 2022

Interestingly, Agfa-Gavert B&W reversal process doesn't use an acid stop bath and instead uses a wash. The first developer is surely highly energetic and alkaline and the wash step is like a two bath development. I wonder why uneven development wasn't a concern in this process.

Ian Grant · Sep 21, 2022

miha said:
Another testament to the above:

View attachment 316888

Source: https://www.photomemorabilia.co.uk/Ilford/Chronology - Intro.html

Although not illustrated it does say the negatives are rinsed after development.

It's also worth noting that pre-WWII fixers were much simpler and sold as raw chemicals, so the 1940 Kodak Ltd Professional Catalogue lists Hyypo (Sodium Thiosulphate) and Potassium Metabisulphite.

The history of Stop Baths and Fixers appears to be over-looked

Ian

miha · Sep 21, 2022

Ian Grant said:
Although not illustrated it does say the negatives are rinsed after development.

It's also worth noting that pre-WWII fixers were much simpler and sold as raw chemicals, so the 1940 Kodak Ltd Professional Catalogue lists Hyypo (Sodium Thiosulphate) and Potassium Metabisulphite.

The history of Stop Baths and Fixers appears to be over-looked

Ian

It's a fascinating topic; before the photo forums, I was only aware of the liquid fixers (FF-2 from Fotokemika), now I'm all too confused with two bath/double strength/sodium/1-minute/alkaline and what not fixing technique, and now alkaline stop baths...

MattKing · Sep 21, 2022

I'm thinking that that Ilford chart doesn't show an acid stop because all the vinegar in England was needed for the chips.

Ian Grant · Sep 21, 2022

MattKing said:
I'm thinking that that Ilford chart doesn't show an acid stop because all the vinegar in England was needed for the chips.

And the pickled eggs sold in all our Pubs Chicken Tikka Masala from Indian takeaways is now more popular than fish and chips.

miha said:
It's a fascinating topic; before the photo forums, I was only aware of the liquid fixers (FF-2 from Fotokemika), now I'm all too confused with two bath/double strength/sodium/1-minute/alkaline and what not fixing technique, and now alkaline stop baths...

There's a history of stop baths, which includes the use of very dilute Hydrochoric or even Sulphuric acids, Potassium Metabisulphite solution, for tropical worked acidified Potassium Alum tanning solutions, Chrome Alum Stop Hardener which was the best hardening stop bath - I used it with EFKE Kb14 in the early 1970s until finding adding a few drops of Formaldehyde to the developer was a better option.

Ian

reddesert · Sep 21, 2022

I think maybe one of Haist's concerns about uneven continuation of development with a water bath instead of stop is unevenness in the time it would take the water to mix into the emulsion to dilute the developer, not just the pour-in time, but this is a total guess. (For dilution you need some large number, say 10-20 units of water to contact each unit of developer, but for altering the pH you only need of order 1 unit of stop to reach each unit of developer.)

My Kodak (USA) Reference Handbook from 1946 discusses acid stop baths with the conventional reasons for use, and also gives formulae for SB-1 through SB-5 - includes acetic acid, chrome alum, and hardening stop baths. It has formulae for developers and fixers, but also an extensive list of which chemicals are sold in premade packets or containers, so that was already common practice in the US in 1946.

I learned to use acid stop bath when learning in the 1980s from Kodak manuals, books, and older relatives. I don't think I ever heard that there were pitched battles over stop bath until the internet.

pentaxuser · Sep 21, 2022

reddesert said:
I don't think I ever heard that there were pitched battles over stop bath until the internet.

That may be because in truth the pitched battles may be caused by the entrenched position taken on the subject by a few rather than a true "fight to the death" for the real and only truth

pentaxuser

albada · Sep 21, 2022

pentaxuser said:
That may be because in truth the pitched battles may be caused by the entrenched position taken on the subject by a few rather than a true "fight to the death" for the real and only truth

pentaxuser

One can fight for the truth or his belief; the two are often not the same.
But this thread in Photrio shows another reason to fight -- for the fun of it.

tomatojoe · Sep 21, 2022

Fun thread! I thought Stop Bath only worked because it was an ACID and developers were BASIC. I guess I was basically wrong!

Ian Grant · Sep 22, 2022

reddesert said:
I think maybe one of Haist's concerns about uneven continuation of development with a water bath instead of stop is unevenness in the time it would take the water to mix into the emulsion to dilute the developer, not just the pour-in time, but this is a total guess. (For dilution you need some large number, say 10-20 units of water to contact each unit of developer, but for altering the pH you only need of order 1 unit of stop to reach each unit of developer.)

My Kodak (USA) Reference Handbook from 1946 discusses acid stop baths with the conventional reasons for use, and also gives formulae for SB-1 through SB-5 - includes acetic acid, chrome alum, and hardening stop baths. It has formulae for developers and fixers, but also an extensive list of which chemicals are sold in premade packets or containers, so that was already common practice in the US in 1946.

I learned to use acid stop bath when learning in the 1980s from Kodak manuals, books, and older relatives. I don't think I ever heard that there were pitched battles over stop bath until the internet.

The wartime Kodak Research Laboratories Formulary W.1 1944 seems to be the first publication of Kodak Formulae, of course individaul formulae had been published from Eastman Kodak's early days. It does include stop baths and calls them Acid Rinse, under the heading Rinse and Hardening Baths. Army and particulary RAF units were mixing some of their chemistry from raw chemicals, the BJP Almanacs of the time show formulae devised in the field by RAF officers.

Hans Windisch's book on modern ways of working "Die Neu Foto Schule" German, The New Photo School" English published in 1938 makes no mention of stop baths. It seems that stopbaths come into more common use during WWII, this is also a point where there were significant improvements in emulsions, Ilord FP3 and HP3 were introduced around 1941.

I have a set of those Eastman Kodak Reference Handbooks, in their original boxes, there were 4. Kodak Professional Handbook, Kodak Reference Handbook 1, Kodak Reference Handbook 2, Kodak Color Handbook. Seems that there were also UK versions as I have a Kodak Ltd, Harrow, Kodak Chemicals and Formulae section in a searate Kodak Refernce Handbook 2.

Ian

Ian Grant · Sep 22, 2022

Oddly the "Kodak Reference Handbook 1", 1946, states for most films "rinse thoroughly in water", then fix, others it adds "or Kodak Stop Bath SB-3 (during hot weather), SB-3 is a Potassiun Chrome alum hardener. Kodak are recommending a stop bath with papers at this point but not for films, except the strong hardening bath in hot weather.

Part of the reason for the use of a stop bath with paper is the far greater carry over of developer alkali into the fixer if a water rinse is used, because at that time all papers were fibre based, a water rinse is sufficient with film.

Ian

BobUK · Mar 27, 2023

Just reviving the topic of alkaline stop bath promoted by John Finch.

Is it meant to improve the archival properties of the film ?

Improve the amount of stain left on the negative thereby improving the contrast in the final prints ?

Is it better than acid fixers for the environment ?

It would be nice to see final test results of both negatives and prints comparing acid and alkaline stop baths.
I do not recall seeing proof of the pudding anywhere.

MattKing · Mar 27, 2023

BobUK said:
Is it better than acid fixers for the environment ?

It washes out of film and papers more easily, so usage can decrease water usage.

pentaxuser · Mar 27, 2023

MattKing said:
It washes out of film and papers more easily, so usage can decrease water usage.

True but usage of water decrease also follows from using RC paper

pentaxuser

relistan · Mar 28, 2023

BobUK said:
Just reviving the topic of alkaline stop bath promoted by John Finch.

Is it meant to improve the archival properties of the film ?

Improve the amount of stain left on the negative thereby improving the contrast in the final prints ?

Is it better than acid fixers for the environment ?

It would be nice to see final test results of both negatives and prints comparing acid and alkaline stop baths.
I do not recall seeing proof of the pudding anywhere.

I have not seen his video but if you are using a staining developer where you think you are getting some advantage from avoiding acids in your process, and using an alkaline fixer, and water stop is not enough for you, then this is a solution.

It ought to be very, very reusable. @Rudeofus mentioned a formula for one recently that he said you could reuse basically forever (he was not promoting it, just giving a formula). But not sure I’d bother to use it personally.

pentaxuser · Mar 28, 2023

BobUK said:
Just reviving the topic of alkaline stop bath promoted by John Finch.

It would be nice to see final test results of both negatives and prints comparing acid and alkaline stop baths.
I do not recall seeing proof of the pudding anywhere.

Yes, Bob, I await that proof with bated breath

pentaxuser

koraks · Apr 1, 2023

relistan said:
you think you are getting some advantage from

That's very carefully and correctly formulated IMO. Emphasis on "think"!

Okay, how does alkaline stop bath actually work?

Raghu Kuvempunagar

Ian Grant

miha

MattKing

Moderator

Ian Grant

reddesert

pentaxuser

albada

tomatojoe

Ian Grant

Ian Grant

BobUK

MattKing

Moderator

pentaxuser

relistan

pentaxuser

koraks

Moderator

Okay, how does alkaline stop bath actually work?

Moderator

Moderator

Moderator

Privacy & Transparency

Privacy & Transparency