AGFA 304 Fixer: Substitution for potassium metabisulfite?

Joe Galloy · May 30, 2017

Hello,

I'd like to mix up a batch of Agfa 304 fixer. I regularly use commercial rapid fixer but also have some hypo and other chemicals on hand in case I run out of commercial fixer. This is the formula for Agfa 304:

Water at 52°C – 750ml
Sodium Thiosulfate – 200g
Ammonium Chloride – 50g
Potassium Metabisulfite – 10g
Water to make 1 litre

In the Darkroom Cookbook, it is mentioned that sodium metabisulfite may be substituted for sodium metabisulfite, and elsewhere, that sodium bisulfite may be substituted for sodium metabisulfite. So...I'm wondering if sodium bisulfite can stand in for potassium metabisulfite. I did some googling and other searches for an answer and didn't see this topic come up before.

Thanks in advance for any help!

JG

john_s · May 31, 2017

Sodium metabisulfite will do fine. Theoretically one could adjust for different molecular weights but there's very little in it. Potassium salts and sodium salts are very similar for photographic purposes.

Rudeofus · May 31, 2017

Sodium Bisulfite (NaHSO3) is a rare compound with very specifically controlled amount of water. It's quite likely that the "Sodium Bisulfite" sold to you is actually Sodium Metabisulfite. Both can be used for Agfa 304 instead of Potassium Metabisulfite.

BTW: Unless you really need an acidic fixer, this recipe can be really improved by lowering Ammonium Chloride to 40-45 g/l and by replacing the 10 g/l Metabisulfite with a mix of 10 g Sulfite and 2-3 g Metabisulfite. This way it will fix faster, wash out much faster and better, and the working solution will last much longer.

Joe Galloy · May 31, 2017

Cool, thanks much to both john_s and Rudeofus for the info!

Joe Galloy · May 31, 2017

Rudeofus said:
BTW: Unless you really need an acidic fixer, this recipe can be really improved by lowering Ammonium Chloride to 40-45 g/l and by replacing the 10 g/l Metabisulfite with a mix of 10 g Sulfite and 2-3 g Metabisulfite. This way it will fix faster, wash out much faster and better, and the working solution will last much longer.

Thanks for the suggestion. I don't need an acid fix. Are you saying that this will result in an alkaline fixer? I also found the Ole's Quick Fix which uses an alkaline buffer and omits the bisulfite altogether.

Rudeofus · Jun 1, 2017

There is a fine pH balance with good fixers which contain Ammonium ion: if pH is too low, they won't last very long, and washing is tedious. If they are too alkaline, they have an awful Ammonia smell which makes them unsuitable for tray processing IMHO. Sadly, Thiosulfate provides little to no buffering between pH 6 and 8, therefore you have to create a Sulfite/Bisulfite or a Sulfite/Acetic Acid buffer with target pH between 6 and 7. The 10 g/l Sulfite plus 2-3 g/l Metabisulfite combo does just that: it provides desperately needed Sulfite ions to protect the Thiosulfate from oxidation, it forms a semidecent buffer somewhere between pH 6 and 7, and its amount is low enough such that fixation is not excessively slowed down.

About the Ammonium Chloride: there appear to exist different sources for this compound with slightly different composition. Tests with my batch of Ammonium Chloride showed steady increase in fixing speed up to about 45 g/l, beyond that level fixer speed would go down again. I have seen at least (there was a url link here which no longer exists) where fixing speed was improved with even higher levels of Ammonium Chloride, so you may have to do some clip clearing time tests with different amounts of Ammonium Chloride.

Ian Grant · Jun 1, 2017

Sodium Bisulphite will be fine unless you buy analytical grade which is very expensive. What's sold as Sodium Bisulphite in North America is a mixture of Sodium Bisulphite and Metabisulphite, it's not pure enough to be called Metabisulphite.

Here in Europe both are available and the MSDS sheets indicate the high purity of the Metabisulphite and the lower purity of the Bisulphite. I used to buy about 100 kg of Sodium Metabisulphite a month and for some uses the higher purity is more critical as it releases more SO2.

Agfa 304 lasts well, I've some that's over 5 years old and it's still fine.

Ian

Joe Galloy · Jun 1, 2017

Rudeolfus and Ian:

Thanks again for the info. It's very helpful!

~andi · Jun 1, 2017

Rudeofus said:
BTW: Unless you really need an acidic fixer, this recipe can be really improved by lowering Ammonium Chloride to 40-45 g/l and by replacing the 10 g/l Metabisulfite with a mix of 10 g Sulfite and 2-3 g Metabisulfite. This way it will fix faster, wash out much faster and better, and the working solution will last much longer.

Rudeofus, could you clarify which Suflite you mean, please? 10g of Potassium Sulfite?

What pH will those modification result in? Will the gelatine be prone to swelling more? And if so, would this modification work with hardener?

Edit: I should have read your post more carefully. I guess the it doesn't matter if its potassium or sodium suflite/metabisulfite.

Andi

Rudeofus · Jun 1, 2017

Ian Grant said:
Agfa 304 lasts well, I've some that's over 5 years old and it's still fine.

That's quite unusual and does not match my experience with acidic fixers, and neither does it match published stability data for acidic thiosulfate based fixers. Did you have it in some special container?

~andi said:
What pH will those modification result in? Will the gelatine be prone to swelling more? And if so, would this modification work with hardener?

The result will have pH somewhere between 6 and 7. If you have too much Sulfite and/or too little Metabisulfite, then pH will be a tad high, which leads to bad Ammonia odors. If you have too much Metabisulfite, your pH will be lower which means slower and more tedious washing and poor working solution shelf life. If you want to find your own mix, I'd start with 10 g/l Sodium Sulfite, then add Metabisulfite in 0.5 g increments until there is no longer any objectionable Ammonia odor.

IIRC, my personal paper fixer recipe right now is 200 g/l Sodium Thiosulfate, 45 g/l Ammonium Chloride, 10 g/l Sodium Sulfite and 2.2 g/l Sodium Metabisulfite. This formula clears Tri-X in about 40 seconds at room temperature, which is pretty close to commercial rapid fixer at 1+4 dilution. Since this formula is substantially lower in pH than most common developers, and since it contains no fixing agent which would promote excessive swelling (I'm looking at you, Thiocyanate! ), I would not expect excessive swelling even in old, unhardened film.

Obviously at pH close to neutral it will not work with typical hardeners, that's where you need acidic fixers like Kodak F-5, F-6 or Agfa 304.

Allow me to share a silly episode here: Since the working solution lasts for many months (assuming usage is low) without any signs of deterioration, I once decided to mix 2 liters in advance before I went on holidays. Bad idea! Since it was never used before storage, there was no silver in this fixer, and it grew mold within few weeks. Had to toss it out and thoroughly clean the canister I kept it in

~andi · Jun 1, 2017

Thank you very much Rudeofus. Very helpful information. I'll proceed as you suggested. And good tip with the not keeping the solution unused for too long.

The swelling problem I have with Fomabrom only. I found the neutral fixer i've been using (Rollei RXN) makes the emulsion come off the paper during longer wet times (3hrs+). I probably need a hardener/acid fix for long sessions with this paper. But that's another topic...

Ian Grant · Jun 2, 2017

Rudeofus said:
That's quite unusual and does not match my experience with acidic fixers, and neither does it match published stability data for acidic thiosulfate based fixers. Did you have it in some special container?

Agfa 304 is quite a simple fixer, I've only made it up a few times and store it in and old May & Baker (now Champion) HD plastic developer bottle, it's barely acidic.

My experience is that some fixers last far better than others, also that diluted last better than highly concentrated where there's a greater risk of sulphurisation over time. Agfa 304 isn't concentrated so this maybe why it keeps well.

Ian

daiamarius · Jun 3, 2017

Hello, here is formula for AGFA 304 rapid fixer

Water at 52°C‡ – 750ml
Sodium Thiosulfate – 200g
Ammonium Chloride – 50g
Potassium Metabisulfite – 20g
Water to make 1 litre

and here is formula ORWO 304 rapid fixer

Water at 52°C‡ – 750ml
Sodium Thiosulfate – 200g
Ammonium Chloride – 50g
Sodium Metabisulfite – 17g
Water to make 1 litre

daiamarius · Jun 3, 2017

I can tell you that I used formula AGFA 304 with Potassium metabisulphite ... 20.0 grams and
ORWO 304 with sodium metabisulfite ...17 grams, and seems to be okay. Normal fixing time for paper is 3 to 5 minutes at 20C

Ian Grant · Jun 3, 2017

Welcome to APUG Daiamarius.

I was just returning to post that the level of Metabisulphite was wrong, and that I made mine up with Sodium Metabisulpite which is far better anyway See a separate thread on Substitute Rodinal and Potassium levels).

It's over 3 years now since I last made up R 304 but I'd guess I'd have substituted the equivalent weight of Sodium Metabisulphite for the Potassium Metabisulphite as I have the conversion ratio in a Spread sheet dates back to at least 2009 and that 17g to 20g is correct - my conversion os based on Molecular weights rounded to 2 figures

I have a couple of East German Agfa Rezepte books 1952 & 1960 so took the formula from one of them. I have a later Orwo Rezeptes book but hadn't spotted the change but then I'm more interested in Developers

Ian

Joe Galloy · Jan 23, 2018

Rudeofus said:
Sodium Bisulfite (NaHSO3) is a rare compound with very specifically controlled amount of water. It's quite likely that the "Sodium Bisulfite" sold to you is actually Sodium Metabisulfite. Both can be used for Agfa 304 instead of Potassium Metabisulfite.

BTW: Unless you really need an acidic fixer, this recipe can be really improved by lowering Ammonium Chloride to 40-45 g/l and by replacing the 10 g/l Metabisulfite with a mix of 10 g Sulfite and 2-3 g Metabisulfite. This way it will fix faster, wash out much faster and better, and the working solution will last much longer.

Rudeofus, I wanted to thank you for this excellent formula. I finally gave it a try and found it to work rapidly (clears HP5+ in 65 seconds), faster than Agfa 304 (80 seconds). The thing I like most about it is its almost complete lack of odor, compared with either commercial rapid fix or Agfa 304. Did you develop this formula yourself, or did you find it somewhere else?

Rudeofus · Jan 24, 2018

Joe Galloy said:
Rudeofus, I wanted to thank you for this excellent formula. I finally gave it a try and found it to work rapidly (clears HP5+ in 65 seconds), faster than Agfa 304 (80 seconds). The thing I like most about it is its almost complete lack of odor, compared with either commercial rapid fix or Agfa 304. Did you develop this formula yourself, or did you find it somewhere else?

I claim authorship of this particular formula, but it did not come out of thin air: I learned a lot from looking at Agfa 304, Ole's Quick fix, Ryuji Suzuki's Neutral Rapid Fixer, and of course Rowland Mowrey's Superfix I.

Doremus Scudder · Jan 24, 2018

Rudi,

My book of formulas lists 20g/l of potassium metabisulfite for Agfa 304. You mention 10g/l... or did you mean that the 20g/l of p. metabisulfite should be replaced with 10g/l sodium sulfite and 2-3g/l metabisulfite? I guess the question is: what is the correct original formula for 304, 20g/l metabisulfite or 10g/l? (It seems that the 20g/l figure is likely the original.) And is then 10g/l sulfite plus the 2-3g/l metabisulfite the substitute for the original 20g/l?

TIA

Doremus

Rudeofus · Jan 24, 2018

My formula is not Agfa 304. With the high mol weight of Sulfite ion, there is little difference in sulfite ion content of equal amounts of sulfite and metabisulfite. Ron's and Ryuji's formulas work @ph 6.5 and are apparently happy and stable with 10-15 g/l Sodium Sulfite/Metabisulfite, so that's what I used in my fixer. Using much more makes the fixer slower. Agfa 304 had to use 20 g/l, because it's so acidic that its shelf life is already miserable compared to my soup.

miha · Jan 24, 2018

Rudeofus, can you please share your complete formula in a single post, that would be most helpful. In addition, can you state the fixing time for paper? Thanks.

faberryman · Jan 24, 2018

No need to substitute. Artcraft Chemicals, my go-to source for photographic chemicals, carries potassium metabisulfite at $11.95/pound.

http://www.artcraftchemicals.com/pr...mistry/n-z/potassium-metabisulfite-part-1305/

Rudeofus · Jan 24, 2018

miha said:
Rudeofus, can you please share your complete formula in a single post, that would be most helpful. In addition, can you state the fixing time for paper? Thanks.

Just did it. I'm glad you tried it and found it useful!

miha · Jan 24, 2018

Rudeofus said:
Just did it. I'm glad you tried it and found it useful!

Thank you. I haven't tried it yet but I plan to do so in the future.

Joe Galloy · Jan 28, 2018

Rudeofus said:
I claim authorship of this particular formula, but it did not come out of thin air: I learned a lot from looking at Agfa 304, Ole's Quick fix, Ryuji Suzuki's Neutral Rapid Fixer, and of course Rowland Mowrey's Superfix I.

All interesting reading. Thanks again!

Olympus17 · Aug 2, 2020

Selam. Bu sabitleyici filmler için uygun mu?

AGFA 304 Fixer: Substitution for potassium metabisulfite?

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