What happens to old thiosulfate fixer?

Snoop · Sep 26, 2023

everywhere I read that plain sodium thiosulfate doesnt keep and will lose its ability to fix just overnight
I find myself using that for fixing, simple pool stuff, but more often than not I end developing one roll and not have time to develop another until the next day or two.
Why the old fixer cant fix anymore (fresh can clear a test clip in 2minutes the day after at 4minutes hasnt fully cleared)? did it become just throwaway or can it be refreshed using a smaller quantity of thiosulfate than if I were to prepare it fresh?
Its not exactly pinching pennies, besides that some pennies add up much faster than others, its mostly the fact that sometimes I run short and it's becoming harder and harder to just walk into a store and buy this or that chemical. (at this rate they will take away sugar from the shelves too)

Edit: forgot to ask about this thread https://www.photrio.com/forum/threads/sodium-thiosulfate-fixer.48212/ where the author mentions a very weak sodium thiosulfate formula for Van Dyke Brown, however his quote from Photo-Imaging: A Complete Visual Guide to Alternative Techniques and Processes also says it would keep for about a year
The fact that VDB fixer would remain useful for one year while the same in a much more concentrated solution would lose its utility in less than a day is the reason I asked what happens to plain simple fixer while its just sitting there.

ags2mikon · Sep 26, 2023

It would help if you told us how you mix it and use it.

Snoop · Sep 26, 2023

ags2mikon said:
It would help if you told us how you mix it and use it.

80g per 320ml water (single reel), 3 times the 2minutes it takes to clear a clip from the leader.
Been reading that should do a couple 35mm rolls, so if I use it for a 12 exposure roll today and cannot use it tomorrow when it could have fixed 2 rolls of 36, I'm wasting much of it.
Last time I rushed to get some none of the stores around me had it so now every time I mix a batch I wonder about it

BTW, I forgot to mention this thread https://www.photrio.com/forum/threads/sodium-thiosulfate-fixer.48212/ so I edited my oroginal post

ags2mikon · Sep 26, 2023

I use the F-5 formula when I want a plain sodium thiosulfate fixer. You can also use Agfa 304 fixer with ammonium chloride.

ags2mikon · Sep 26, 2023

As far as a easy fixer to find locally the Agfa 304 is nice. Sodium thiosulfate is in the pool supply isle and Ammonium chloride is at the livestock store and sodium metabisulfite an the wine making store. Haven't found metol and hydroquinone like that. You can use the metabisulfite as a stop bath too. Dual use.

Rudeofus · Sep 26, 2023

Plain thiosulfate (with no addition of sulfite) will pick up Oxygen and form sulfate, which is a lot more acidic than thiosulfate. Apparently it doesn't take much of this reaction to happen to make pH drop below 4. At this low pH the thiosulfate ion will form sulfite ion plus sulfur, i.e. the fixer is toast.

If you add sulfite to "plain hypo fixer", the fixer will last at least some weeks. If you add sulfite and make sure, that the fixer starts off at pH >= 6.5, then your fixer will last for many months if not years. Sulfite is cheap, there's no reason not to use it, unless you are already sure, that you will exhaust your fixer in a single dark room session.

juan · Sep 26, 2023

Look up TF-2

Snoop · Sep 26, 2023

I'm aware that I can use "proper" fixer from a camera store, my point was: why it happens and how can I make the best use of what I already have at home, while I have it....

ags2mikon said:
As far as a easy fixer to find locally the Agfa 304 is nice. Sodium thiosulfate is in the pool supply isle and Ammonium chloride is at the livestock store and sodium metabisulfite an the wine making store. Haven't found metol and hydroquinone like that. You can use the metabisulfite as a stop bath too. Dual use.

The only livestock/farm supplies store around me is gone, the "wine making store" also a wash for different reasons
Some years ago I had places where I could go with a list of so much of this and so much of that and mix my own stuff, then places like that disappeared and had to adapt to mismatched quantities of just some stuff. Now there are even fewer stores, with less and less stuff available, and getting more expensive. Going that route at this point is less convenient than going into a camera store and getting a kit and in the future I might just pile up my remaining film, get a kit and develop the bunch.

Rudeofus said:
Plain thiosulfate (with no addition of sulfite) will pick up Oxygen and form sulfate, which is a lot more acidic than thiosulfate. Apparently it doesn't take much of this reaction to happen to make pH drop below 4. At this low pH the thiosulfate ion will form sulfite ion plus sulfur, i.e. the fixer is toast.

If you add sulfite to "plain hypo fixer", the fixer will last at least some weeks. If you add sulfite and make sure, that the fixer starts off at pH >= 6.5, then your fixer will last for many months if not years. Sulfite is cheap, there's no reason not to use it, unless you are already sure, that you will exhaust your fixer in a single dark room session.

thanks for the explanation
can older plain thiosulfate be used as source of sulfate or sulfite then?
(dont they make thiosulphate from solutions of sulfite and sulphur?)

Rudeofus · Sep 26, 2023

Snoop said:
can older plain thiosulfate be used as source of sulfate or sulfite then?
(dont they make thiosulphate from solutions of sulfite and sulphur?)

It's the Sulfur, which you don't want in your film, since it will react with image silver over time and turn black Silver into brown Silver Sulfide. It will not do this uniformly, and it is irreversible once it happens. Yes, there are methods to break up Silver Sulfide, but they will also break up the gelatin.

At the same time I am quite sure, that there has to be a source of Sodium Sulfite somewhere within driving distance. You may not like that wine making store, but holding your nose tight while you purchase 1 kg Sodium Sulfite from them will solve the fixer durability issue for many years to come. Since Sodium Sulfite is alkaline anyway, you may even reach stage 2 (thiosulfate plus sulfite and alkaline): that fixer may last for months if you don't overuse it.

Snoop · Sep 27, 2023

Rudeofus said:
IAt the same time I am quite sure, that there has to be a source of Sodium Sulfite somewhere within driving distance. You may not like that wine making store, but holding your nose tight while you purchase 1 kg Sodium Sulfite from them will solve the fixer durability issue for many years to come. Since Sodium Sulfite is alkaline anyway, you may even reach stage 2 (thiosulfate plus sulfite and alkaline): that fixer may last for months if you don't overuse it.

Oh its not a matter of not liking the stores.
Where Im living right now, the "winemaking" stores closeby turned to sell just the kits, one hour drive can give me the 1kg (not 100gr) of sulfite for 20$+ gas and time, but: all that to maintain my remaining 300gr of thiosulfate (after which Im out since they seem not to sell it anymore here) and all when a camera store has full dev kits for 50$ and fixer for 16-20$... ?
As is Im basically trying to use what I have in the best way, which at this point I would say is just to develop several rolls the same day and exhaust the solution.
Sadly the rest is left to just plain curiosity (or to know for when I will be moving somewhere else).

Thanks for the explanation.

koraks · Sep 27, 2023

Snoop said:
to maintain my remaining 300gr of thiosulfate

If you have 300g of dry thiosulfate sitting there, it'll keep well pretty much indefinitely. Dry sodium thiosulfate is pretty stable. Dry ammonium thiosulfate tends to pick up water from the air, resulting in clumping, and then decomposes. I assume we're talking about sodium thiosulfate.

Using your dry sodium thiosulfate is easy; just mix up what you need for a particular job (fixing film, VdB's etc.), use, and discard. That way you don't have to worry about preservatives etc. Just plain thiosulfate will fix just fine, but for (modern) film, it's a bit of a slow fixer and some films are difficult to fix entirely with it (e.g. TMAX). for prints like VdB and salt prints, be sure to fix sufficiently long; 10 minutes or so, at least. Due to the absorbent nature of the papers we generally print on with these processes, they fix out really, really slowly. Incompletely fixed prints will look fine at first, but will start to show yellowing after a few months or years. It sucks if you have that one print that came out really nice framed on your bedroom wall and you start noticing this yellow stain all over it...

Snoop said:
they seem not to sell it anymore here

Sodium thiosulfate is widely used for swimming pool maintenance. It's often sold in hardware stores for this purpose.
I'd recommend just purchasing photographic rapid fixer, though.

Rudeofus · Sep 27, 2023

koraks said:
I'd recommend just purchasing photographic rapid fixer, though.

I agree with this. If @Snoop buys neutral rapid fixer concentrate, it will live forever and be less hassle. And he'd keep the remaining 300g Sodium Thiosulfate for those rare cases, when he runs out of regular fixer concentrate.

lamerko · Sep 27, 2023

For quite some time I have worked with A300 - the ORWO/Calbe sour formula:

Sodium thiosulfate - 200 g.
Potassium metabisulfite - 20 g.

Lasts very long. Even right now I have a forgotten solution of more than a year - it has already started to decompose, but I guess it is still active.
Sodium thiosulfate is cheap and can be stored in crystalline form for tens of years. But it is slow acting (without super additives) and there are doubts that it can clean modern color film.

Snoop · Sep 27, 2023

koraks said:
If you have 300g of dry thiosulfate sitting there, it'll keep well pretty much indefinitely. Dry sodium thiosulfate is pretty stable. Dry ammonium thiosulfate tends to pick up water from the air, resulting in clumping, and then decomposes. I assume we're talking about sodium thiosulfate.

Using your dry sodium thiosulfate is easy; just mix up what you need for a particular job (fixing film, VdB's etc.), use, and discard. That way you don't have to worry about preservatives etc. Just plain thiosulfate will fix just fine, but for (modern) film, it's a bit of a slow fixer and some films are difficult to fix entirely with it (e.g. TMAX). for prints like VdB and salt prints, be sure to fix sufficiently long; 10 minutes or so, at least. Due to the absorbent nature of the papers we generally print on with these processes, they fix out really, really slowly. Incompletely fixed prints will look fine at first, but will start to show yellowing after a few months or years. It sucks if you have that one print that came out really nice framed on your bedroom wall and you start noticing this yellow stain all over it...

I know that dry keeps for years, what Im talking about is mixing a batch to cover one single reel and that batch has the ability to be reused for 2 rolls of film in total but the waste is in using it for just one 12 exposure roll because I cant get to the second roll until the day after.
Its like always pouring a glass of beer, drinking less than half and the morning after its garbage (for fixer is about concentration not quantity of solution)... we would all agree that's wasting beer....
And my understanding is that I cant do half dilution and make it go for 10+ minutes with fixer (there was a thread I saw where someone asked what's the weakest they could go to limit the waste and they didn't really get an answer)

Snoop · Sep 27, 2023

koraks said:
Sodium thiosulfate is widely used for swimming pool maintenance. It's often sold in hardware stores for this purpose.

Around here WAS sold in hardware stores, now they are changing the chlorine reducers with something else, I find things with labels listing sodium bisulfate others list copper sulfate, but for the majority of products ingredients on labels are gone and even MSDS have been pulled
What I was buying for 3$ just pre-pandemic now is 11$ and listed out of stock (and according to the guy at one of the stores with a note "not to be restocked" in their inventory system)
Bromides/bromines also got banned recently

koraks said:
I'd recommend just purchasing photographic rapid fixer, though.

Rudeofus said:
I agree with this. If @Snoop buys neutral rapid fixer concentrate, it will live forever and be less hassle. And he'd keep the remaining 300g Sodium Thiosulfate for those rare cases, when he runs out of regular fixer concentrate.

Yes of course. yesterday still used to be that getting the stuff from the normal hardware stores and mixing what was needed was cheaper than paying the "photo dev chemicals" premium. Today not only prices of the generic stuff is gone way up but the hassle to find it have changed the "proper stuff" into the more convenient option.
Its a drastic change in just a few years, stores were low on certain things during the pandemic and after that some stuff is simply not allowed anymore...
Rudeofus: I guess that would be the sensible thing to do

My gf, which had no problems abandoning film long time ago, lately looked at me and asked me if I was still having fun using film...
I have to say its getting less and less

Snoop · Sep 27, 2023

lamerko said:
For quite some time I have worked with A300 - the ORWO/Calbe sour formula:

Sodium thiosulfate - 200 g.
Potassium metabisulfite - 20 g.

Lasts very long. Even right now I have a forgotten solution of more than a year - it has already started to decompose, but I guess it is still active.
Sodium thiosulfate is cheap and can be stored in crystalline form for tens of years. But it is slow acting (without super additives) and there are doubts that it can clean modern color film.

What stores here carry is Ilford, Kodak, and the Tetenal in tablets.
They dont cost a lot so thats gonna be the best choice from now on
For color a C41 kit is gonna take care of the 15 or so color rolls I still have in the freezer

lamerko · Sep 27, 2023

In the EU, Foma sells a dry fix based on sodium thiosulfate. Sodium thiosulfate is also readily available at specialty chemical stores - about $6/kg. Unfortunately, ammonium thiosulfate is harder to find. The problem is that it is available as a 60% solution and many companies refuse to sell it. The agricultural pharmacy requires a minimum order quantity of 1000 liters. Photographic stores sell concentrates, but they usually have a vague and acidic formula, which is not good for color materials. It's good that Fototechnik Suvatlar has it - I bought a 5 liter tube of 60% from them

Snoop · Sep 27, 2023

lamerko said:
In the EU, Foma sells a dry fix based on sodium thiosulfate. Sodium thiosulfate is also readily available at specialty chemical stores - about $6/kg. Unfortunately, ammonium thiosulfate is harder to find. The problem is that it is available as a 60% solution and many companies refuse to sell it. The agricultural pharmacy requires a minimum order quantity of 1000 liters. Photographic stores sell concentrates, but they usually have a vague and acidic formula, which is not good for color materials. It's good that Fototechnik Suvatlar has it - I bought a 5 liter tube of 60% from them

in the area of Canada where Im now agri stores refuse to sell you trivial kaolin, go figure the rest

What happens to old thiosulfate fixer?

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