A Neutral Quick Fixer Formula

Rudeofus · Jan 24, 2018

Rudeofus submitted a new resource:

A Neutral Quick Fixer Formula - odorless neutral sodium thiosulfate ammonium chloride fixer formula

I present here an odorless quick acting fixer based on Sodium Thiosulfate:

200 g/l Sodium Thiosulfate Pentahydrate (= crystalline)
40-45 g/l Ammonium Chloride
10 g/l Sodium Sulfite
2.2 g/l Sodium Metabisulfite

Resulting pH is about 6.5, which makes it near odorless (neither sulfite nor ammonia odor), quick acting (not as fast as Ammonium Thiosulfate based fixers, but close) and quick to wash out.

Since paper and film properties are all over the place, I can not provide...

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~andi · Feb 21, 2018

Also see here for prior discussion: https://www.photrio.com/forum/threa...stitution-for-potassium-metabisulfite.147271/

I like it. Very few chemicals, easy to get here and to mix ad hoc. In case you have trouble finding "Sodium Metabisulfite" in good 'ole europe, it's called "Sodium disulfite" here over here ("Natriumdisulfit" in german).

In a single bath setup I find I can fix about 15 5x7s Ilford FB in 1L before it reaches 0.5g/l (AgX-Test strips and different subject matter so... accuracy is on a sliding scale).

Pixophrenic · Feb 27, 2018

Rudeofus said:
Rudeofus submitted a new resource:

A Neutral Quick Fixer Formula - odorless neutral sodium thiosulfate ammonium chloride fixer formula

Read more about this resource...

pH of any commercial acid fixer can be adjusted with sodium hydroxide. For example, a simple way to convert Ilford Rapid Fixer into an alkaline fixer (pH ~ 8) is to dissolve 5.4 g of sodium hydroxide (caustic soda) in 800 ml of water, then add 200 ml of the fixer concentrate into it and mix. I made this to go with Pyrocat developer and water wash. The resultant solution has barely noticeable ammonia odor and keeps well with occasional use. If you are in possession of a pH indicator paper, you can add less hydroxide to your desired pH.

relistan · Jan 24, 2021

I mixed up this fixer this weekend and it works great! Ran a couple of rolls through. Original Agfa APX-100 clears in about 30 second and 4 mins of fixing at 65F (what I normally do) worked great. There is no odor at all. You can get a faint whiff of fixer smell if you stick your nose right in it. Would be nice for tray work. Thanks @Rudeofus !

Peter Schrager · Jan 24, 2021

Does anyone have clue as to how many films a liter if this will fix??

Rudeofus · Jan 25, 2021

In terms of capacity this fixer will be similar to plain hypo fixers, only its speed approaches that of rapid fixers. Plain hypo fixers are particularly poor with high iodide emulsions. The exact capacity strongly depends on what you fix. If you don't change materials too often, a few clip tests at the beginning will give you a good estimate.

Pixophrenic · Jan 29, 2021

Rudeofus said:
Rudeofus submitted a new resource:

A Neutral Quick Fixer Formula - odorless neutral sodium thiosulfate ammonium chloride fixer formula

Read more about this resource...

Rudeofus, I am generally not that much into fixers, but since there is a continuing interest about an odorless fixer, I made the small scale experiment as follows. 20 g of hypo and 4 g of ammonium chloride were dissolved in 85 ml of water. This solution had a pH of 6.4 (at 25 degrees Celsius), so it could be used as such for fixing and it does not smell. In older times it was recommended to furnish it with 20-40 g of sodium or potassium metabisulfite, in which case the pH would drop to about 5. Your intention as I understand it was to supply a suitable mixture of sulfite and metabisulfite so as to keep the original pH and also prevent thiosulfate from oxidation to extend the lifetime of it. Now, why stop where you did and not at double or even quadruple the concentration of this additive? As I said elsewhere, it is easy to shift the pH of a commercial fixer, such as Ilford’s by addition of caustic alkali, which partially converts a bisulfite present in it into a sulfite.

So, I proceeded further with my little concoction and gradually added sodium sulfite and measured the pH. The first gram shifted the pH to 7.9, but each subsequent gram shifted it only by 0.1 unit, so at 4 grams (that is 40 g/L) it was 8.3, practically the same as in a typical fine-grain developer. One could stop there, too, because there is only barely detectable smell of ammonia, but I changed the pH back to neutral (6.9) by addition of 6 ml of 15% sodium bisulfate (this is sulfate, not sulfite).

Finally, I adjusted the volume to 100 ml and measured the clearing time of some films, after a pre-soak in distilled water for 3 minutes. Foma 100 cleared in 45 seconds (with agitation), while Ilford Delta 400 and Kodak Tmax 400 both required four full minutes to clear in the fixer as made above. Tmax 400 film still retained a tan-colored tint of the base, which did not completely go away after a several minute wash, while initial purple tint of Delta base was mostly washed away. So, I would hesitate to use this fixer on a Tmax, while with Foma it could actually be used at half-strength until the clearing time becomes too long. In summary, I support your idea, but the sulfite/bisulfite supplement could be made 4X stronger.

Rudeofus · Jan 30, 2021

There were several Sodium Thiosulfate plus Ammonium Chloride based fixer recipes out there, and I did inherit some of their concepts in my concoction. There is Agfa 304, which I initially used to fix my prints. At a later point I ran across OF-1 fixer, which is quite alkaline and therefore IMHO unsuitable for open tray processing. I did get a lot of advice from PE about quick fixers with long shelf life. Here is the rationale behind the fixer recipe as posted here:

We both seem to agree on the 200 g/l number for Sodium Thiosulfate, this is what most formulas seem to use. Sodium Thiosulfate shows absolutely no buffering between 6 and 8. Therefore I knew I have to add some other salt to keep pH between 6.5 and 7.
PE's advice was to pick pH 6.5, so this is what I did.
As oxygen enters the scene, it will at first oxidize sulfite ions, then thiosulfate. The former process decreases pH somewhat, the latter processes quickly drops pH below 4. It is therefore necessary to have some amount of sulfite in thiosulfate based fixers. PE recommended somewhere around 10 g/l. Fortunately sulfite ion provides acceptable buffering at pH 6.5. I started with 10 g/l Sodium Sulfite and added Sodium Metabisulfite until pH dropped down to 6.5.
Fixer speed is improved by the presence of small cations (ammonium < hydrated potassium < hydrated sodium < hydrated lithium), therefore potassium and ammonium ion will speed up Sodium Thiosulfate based fixers. I did experiments with Ammonium Chloride level to optimize fixer speed, this is how I arrived at the 45 g/l level.
Fixer capacity is reduced by certain cations, especially potassium and sodium ion. Several complexes of silver, alkali, halide and thiosulfate can form, some of them insoluble. As silver halide concentration goes up, these insoluble complexes become the dominant form and effectively restrict removal of silver ions. Therefore the presence of ammonium does not improve fixer capacity! These highly insoluble complexes form earlier with bromide and even earlier with iodide.
Therefore any fixer with substantial amount of sodium or potassium will be quite poor for film. This fixer was intended for prints, which are mostly Silver Chloride and some Silver Bromide, but usually low in Silver Iodide. I am not at all surprised, that this fixer does poorly with modern high iodide film.

ruilourosa · Jan 30, 2021

I use something similar: just eliminating the ss and adding about the same of borax, pointing more 7 on pH and becoming odourless to the darkroom and hands...

Pixophrenic · Jan 31, 2021

Rudeofus said:
There were several Sodium Thiosulfate plus Ammonium Chloride based fixer recipes out there, and I did inherit some of their concepts in my concoction. There is Agfa 304, which I initially used to fix my prints. At a later point I ran across OF-1 fixer, which is quite alkaline and therefore IMHO unsuitable for open tray processing. I did get a lot of advice from PE about quick fixers with long shelf life. Here is the rationale behind the fixer recipe as posted here: <snip>

I agree with you for the most part, and apparently you repeated the experiments of Mees, which are described in detail in the Jacobsons book "Developing" (18th edition page 265), hence I agree with the ratio of hypo to ammonium chloride, it is optimal. Nevertheless, my purpose was to demonstrate that such a formulation for certain films is not adequate and also to add some quantitative dimension to just how different films are with regard to your formula. It is not that films and paper are all over the place, but specific films namely containing high iodide, should be fixed in a substantially different formulation. I recall late PE mentioned this a number of times, but probably with regard to color negative films. Also your phrase that "Therefore any fixer with substantial amount of sodium or potassium will be quite poor for film." is not precise. Define "substantial amount". I would say amounts of sulfite in BW fixers were all over the place (5-25 g/L), and they could also contain sodium or potassium metabisulfite (up to 30 g/L), which, as I applied to your case of a higher working pH, could be adjusted with hydroxide, making effective sulfite concentration to 40 g/L. So quadrupling your initial concentration of sulfite will not make the fixer to perform poorly on a "classic" emulsion, as I demonstrated on Foma film. I do not see where do you see the problem in that if your sodium ion is still largely supplied by hypo.

On a related note, historically introduction of hypo as a replacement for cyanide met with serious skepticism, and surprisingly so was the introduction of ammonium thiosulfate, which was associated with a rumor that it produced less stable images (not true). Ammonium thiosulfate makes for a considerably faster fixer, so that for current 100 ASA films it can even be used at only 60 g/L to achieve initial clearing time of 2 minutes. This fact also allows you not to abuse your fixer to the max and forget most complications associated with gradual carryover from developer and stop bath. You just need to watch the clearing time. Then again, for those high iodide films even 150 g/L of this salt may not be enough, one needs additional accelerators (remember PE's Superfix?).

BTW, as an illustrarion, a Fuji color reversal chemistry (posted somewhere on this forum) contains a fixer which is ~78 g/L ammonium thiosulfate and 5 g/l of each of sodium sulfite and sodium bisulfite, pH 6.6.

bedrof · Jun 1, 2021

@Rudeofus thanks for the recipe!
When mixing it should I follow the order in the listing? I mean first dissolve hypo, then add Ammonium Chloride and so on

Rudeofus · Jun 1, 2021

bedrof said:
@Rudeofus thanks for the recipe!
When mixing it should I follow the order in the listing? I mean first dissolve hypo, then add Ammonium Chloride and so on

In order to get the ingredients dissolved with the least amount of time, I recommend the following procedure:

Fill a container with about 60% of intended fixer volume with hot tap water (50-60°C/120-140°F).
Add the calculated amount of Sodium Thiosulfate
Stir vigorously. The Sodium Thiosulfate will cool down the water substantially while it dissolves. If you do not start with very hot water, the solution will get close to freezing point and dissolution will be extremely slow.
After the Sodium Thiosulfate has been dissolved, add the Ammonium Chloride. This will cool down the solution yet more. If the volume is still below the intended final volume, add hot water to reach it. Chances are, that the solution will reach roughly room temperature.
Add the Sodium Sulfite and the Sodium Metabisulfate at once and dissolve it. You should now have an ever so slightly milky solution, which should be mostly odorless.

bedrof · Jun 4, 2021

Rudeofus said:
In order to get the ingredients dissolved with the least amount of time, I recommend the following procedure:

Fill a container with about 60% of intended fixer volume with hot tap water (50-60°C/120-140°F).

Add the calculated amount of Sodium Thiosulfate

Stir vigorously. The Sodium Thiosulfate will cool down the water substantially while it dissolves. If you do not start with very hot water, the solution will get close to freezing point and dissolution will be extremely slow.

After the Sodium Thiosulfate has been dissolved, add the Ammonium Chloride. This will cool down the solution yet more. If the volume is still below the intended final volume, add hot water to reach it. Chances are, that the solution will reach roughly room temperature.

Add the Sodium Sulfite and the Sodium Metabisulfate at once and dissolve it. You should now have an ever so slightly milky solution, which should be mostly odorless.

Thank you, much appreciated!

bernard_L · Jun 4, 2021

@Rudeofus: Thank you. I have since decades some 500g of Ammonium Chloride, bought to prepare T55 Selenium toner. Of course, I used only a small part; Now I can put it to good use.
It seems that Ammonium Thiosulfate is used as a fertilizer around here (EU). But it is sold by truckloads, or at least by the ton. I keep telling myself I should call nearby agricultural co-ops and ask if they would sell me 10 litres. Then I would have the ammonium, the thiosulfate, without the sodium.

Anon Ymous · Jun 4, 2021

bernard_L said:
@Rudeofus: Thank you. I have since decades some 500g of Ammonium Chloride, bought to prepare T55 Selenium toner. Of course, I used only a small part; Now I can put it to good use.
It seems that Ammonium Thiosulfate is used as a fertilizer around here (EU). But it is sold by truckloads, or at least by the ton. I keep telling myself I should call nearby agricultural co-ops and ask if they would sell me 10 litres. Then I would have the ammonium, the thiosulfate, without the sodium.

Or you could try your local agricultural supplies shop, as I did. I found 15, 5 and 1l bottles and got a 5l one for 15€.

Alan Johnson · Jun 4, 2021

Rapid fixer without Ammonium thiosulfate | Photrio.com Photography Forums
What do you think of the fixer investigated by Relayer, post 9, solution 2?
Sodium Thiosulfate.......................200g
Ammonium Chloride......................86g
Water to..........................................1L
Suppose it was kept in a sealed container to avoid oxidation and pH drop and used only for film?

Rudeofus · Jun 5, 2021

Alan Johnson said:
Rapid fixer without Ammonium thiosulfate | Photrio.com Photography Forums
What do you think of the fixer investigated by Relayer, post 9, solution 2?
Sodium Thiosulfate.......................200g
Ammonium Chloride......................86g
Water to..........................................1L
Suppose it was kept in a sealed container to avoid oxidation and pH drop and used only for film?

I have made many experiments with Sodium Thiosulfate and Ammonium Chloride, and with my stash of Ammonium Chloride an amount of 40-50 g/l was the optimum value. Above 50 g/l fixing speed would actually go down again. I did see Relayer's postings back then and did notice the much higher level of Ammonium Chloride in his formula. TBH I have no explanation for this discrepancy, except for maybe significant impurities in my stash of Ammonium Chloride, which may not be present in Relayer's stash. My Ammonium Choride was technical purity at best, delivered in a crude paper bag holding 20kg. People with more refined products may be able to replicate Relayer's formula with better success, however, the beauty of my formula lies in the insanely cheap ingredients. By the time you have to use analytical grade components, you might as well use Ammonium Thiosulfate.

Ansel Adams already tinkered with a sulfite free thiosulfate fixer, and this fixer is said to last a few hours in open trays. Also note, that the sulfite/metabisulfite in my fixer formula not only keeps the thiosulfate intact for many months, it also provides a decent amount of buffering. Regardless of whether you use a stop bath or go directly from developer to fixer, you will quickly see the pH change with a thiosulfate only fixer. The Ammonium Chloride will only make matters worse, because now a high pH will make this fixer reek to high heaven.

Pixophrenic · Jan 13, 2022

Pixophrenic said:
<snip>
So, I proceeded further with my little concoction and gradually added sodium sulfite and measured the pH. The first gram shifted the pH to 7.9, but each subsequent gram shifted it only by 0.1 unit, so at 4 grams (that is 40 g/L) it was 8.3, practically the same as in a typical fine-grain developer. One could stop there, too, because there is only barely detectable smell of ammonia, but I changed the pH back to neutral (6.9) by addition of 6 ml of 15% sodium bisulfate (this is sulfate, not sulfite).<snip>

As a matter of storage update, this solution was retested for clearing time after a year of storage unused. It shows basically the same clearing time depending on film (no Foma 100 on hand, RPX100 65 seconds, Foma 200 1 min 30 sec, Delta 400 and Tmax 400 4 minutes).

bernard_L · Apr 26, 2025

@Rudeofus and all,
I have renewed interest in the formula that you published A Neutral Quick Fixer Formula
I have a couple questions, but first context. I currently use Foma rapid fixer @1+5 (as per the tech datasheet) for both film and paper. Problem is smell when fixing paper in tray. I got sick a couple times after printing sessions, and while I can't prove it, I suspect it is from fixer fumes. Either acetic acid (part of Foma's formula) or SO2 released in the acidic fixer. I see two possible remedies:

Neutralize the Foma fixer with ammonia (pH paper or pH meter).
Question: is that expected to significantly decrease the odor? Would you generally recommend this approach? Pro: no need to procure/store thiosulfate, ammonium chloride, bisulfite, and mix them.
Use your formulation. Pro: properly tested as such versus tinkering with a commercial product. Then there are the following issues questions:

Capacity. Clip tests with film (traditional grains) for both the paper and the film fixer; I already do them regularly; discard when clearing time is 2x initial value. Agree?
Fixing duration for paper. For film, I always check the clearing time and fix for 2x that. For paper, so far, I go by the manufacturer's recommendations; blind faith. Can I assume that the proper/safe fixing time for paper is in proportion to the clearing time, i.e. if the clip test clearing time for your fixer is 1.5x (say) that of commercial fixer "X", then the same extension factor can be applied to the times listed for paper fixation?

koraks · Apr 26, 2025

bernard_L said:
Question: is that expected to significantly decrease the odor?

Yes, this should help alright. The acetate that forms is virtually odorless. However, handling the ammonia can be obnoxious to the mucous membranes, so maybe you're better off giving it a try with something else, like sodium hydroxide (=odorless).

bernard_L said:
Can I assume that the proper/safe fixing time for paper is in proportion to the clearing time, i.e. if the clip test clearing time for your fixer is 1.5x (say) that of commercial fixer "X", then the same extension factor can be applied to the times listed for paper fixation?

I expect this to be a safe approximation, yes.

Rudeofus · Apr 26, 2025

bernard_L said:
@Rudeofus and all,
I see two possible remedies:

Neutralize the Foma fixer with ammonia (pH paper or pH meter).
Question: is that expected to significantly decrease the odor? Would you generally recommend this approach? Pro: no need to procure/store thiosulfate, ammonium chloride, bisulfite, and mix them.

Use your formulation. Pro: properly tested as such versus tinkering with a commercial product. Then there are the following issues questions:

Capacity. Clip tests with film (traditional grains) for both the paper and the film fixer; I already do them regularly; discard when clearing time is 2x initial value. Agree?

Yes, the 2x clearing time rule is well established and also found its way into scientific literature.

Regarding capacity: any fixer with lots of sodium or potassium in the mix will have much reduced capacity compared to a rapid fixer. If you have access to an affordable rapid fixer: use it, and forget these "quick fixers" and "plain hypo fixers". There are situations, where pH needs to be high, or where a large sack of Sodium Thiosulfate happens to land in your darkroom, or where liquid stuff can't be shipped, that's where this "neutral quick fixer" is probably one of the best options out there.

If you want the overall best, cheapest and completely odorless fixer, get fixer concentrate from color processing. You get these in 10 or 20 liter canisters, and both concentrate and working solution will last forever. Five years ago I bought three canisters of C-41 fixer concentrate, and that stuff still works like new. Some minilab fixers will be somewhat on the alkaline side and have a slight but recognizable Ammonia odor, but that's trivially solved with a few dashes of acetic acid.

If this fails, you can try to add Sodium Metaborate to your rapid fixer to get pH to 6.5. Try to maintain pH between 6 and 7, below 6 you will have Sodium Dioxide smell, above that you will have Ammonia smell. The good thing about the metaborate over Sodium Hydroxide is 1. that it sounds less scary and 2. that it provides additional buffering, which helps if you go directly from stop bath to fixer. You may also get away with Borax if metaborate is hard to find.

Sadly I am still not aware about a working clip test for paper, the only way to verify complete fixation is one of these "retained silver tests". Droplets of selenium toner or sulfur toner should be all it takes. I'll try pyrosulfite next time I get around to it. For the extra frugal I wonder, whether a printout test in direct summer sun light would also qualify.

FotoD · Apr 26, 2025

bernard_L said:
Neutralize the Foma fixer with ammonia (pH paper or pH meter).
Question: is that expected to significantly decrease the odor? Would you generally recommend this approach? Pro: no need to procure/store thiosulfate, ammonium chloride, bisulfite, and mix them.

6ml 25% NH3 per 100ml Fomafix stock sol. gives a working sol with pH 7 - 7.5.

The ammonia smells quite a bit. Just add less, and you should get a fixer with less smell.

bernard_L · Apr 26, 2025

@koraks, @Rudeofus, @FotoD,
Thank you for your responses. To the point and informative Not always a given
Short term: will add some Ammonia... outdoors. And resume printing.
Medium term: will put to good use some available but unused sodium hyposulfite and ammonium chloride.
Longer term: will kindly ask the one remaining photolab here in Grenoble to re-sell me 5 litres of C-41 fixer.

bernard_L · Apr 28, 2025

Questions to the knowledgeable ones, after doing a little homework.

pH. Fixers for C-41 are specified having a pH 7.5...7.8, while rapid fixers for B&W are specified pH 5.0...5.5. What are the trade-offs? Acid fixer, that I used so far, allows me (after a brief dip in acid stop) to turn the lights on as soon as the test strip is in the fixer. Neutral fixer will require a longer (30s??) stay in the stop bath. OTOH, neutral fixer is expected to be odorless. Any other trade-offs that i should know of?
Durability. C-41 fixer is generally sold in a pack of 5L concentrate. I'm a relatively low volume user. How long will the stock fixer keep before it sulfurs out?
Choice of C-41 fix. I found the best price is Champion Mydoneg; a distributor sell it for 30€ plus hipping for 5L concentrate. Is Champion still a reputable brand?

CHAMPION - Fixateur C41-RA Mydoneg Universal pour faire 2x5L à 2x15L - CHIMIE Couleur/Développeuse C41 - PH Distrib.com

CHAMPION - Fixateur C41-RA Mydoneg Universal pour faire 2x5L à 2x15L de Champion est vendu sur la boutique PH Distrib.com dans la catégorie Développeuse C41

www.phdistrib.com

Thank you for reading.

koraks · Apr 28, 2025

bernard_L said:
Fixers for C-41 are specified having a pH 7.5...7.8

A little lower AFAIK; 7-7.5 But that's not a very meaningful difference.

bernard_L said:
What are the trade-offs?

AFAIK the main reason for B&W fixers to be acidic is to prevent dichroic fog under conditions of developer carryover due to failure to use a stop bath or thorough rinse. Since in C41 processing, there's the (acidic) bleach between the dev and fixer, the fixer doesn't need to be acidic. There's to the best of my knowledge no disadvantage to having a pH neutral fixer; if anything, the opposite, as it should prolong the lifetime of the fixer concentrate. An acidic fixer is more prone to sulfuring out.
In terms of fixing speed/rate, you would have to look up what PE has said on the topic; if memory serves, pH neutral and alkaline fixers should be a little faster.

bernard_L said:
How long will the stock fixer keep before it sulfurs out?

I buy FujiFilm N3R fixer replenisher, which I haven't seen go bad, ever, even in a partially full container. I couldn't say how long it takes to sulfur out, but I'd say much longer than a year in an opened container, and at least several years in a factory-sealed container.

bernard_L said:
Is Champion still a reputable brand?

I couldn't say, but a C41 fixer is pretty much just ammonium thiosulfate and a little ammonium bisulfite. It's so simple that I don't see how a manufacturer could ever manage to f* this up.

A Neutral Quick Fixer Formula

Rudeofus

~andi

Pixophrenic

relistan

Peter Schrager

Rudeofus

Pixophrenic

Rudeofus

ruilourosa

Pixophrenic

bedrof

Rudeofus

bedrof

bernard_L

Anon Ymous

Alan Johnson

Rudeofus

Pixophrenic

bernard_L

koraks

Moderator

Rudeofus

FotoD

bernard_L

bernard_L

CHAMPION - Fixateur C41-RA Mydoneg Universal pour faire 2x5L à 2x15L - CHIMIE Couleur/Développeuse C41 - PH Distrib.com

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A Neutral Quick Fixer Formula

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