Ammonium thiosulfate/ Sodium thiosulfate, what's the difference?

[markbau]

I have mixed my own developers for years but for some reason, never mixed my own fixers. David Vestal gives a formula for a "Zone V non-hardening rapid fixer" in the Preston Publications "Advanced B&W Printing" which has "ammonium thiosaulfate 60% solution, 800ml"
Way Beyond Monochrome gives two fixer formulas, both containing ammonium thiosulfate.
The problem is I cannot find a supplier for ammonium thiosulfate, the two places in Australia that sell photo chemicals, VanBar and Gold Street studios don't list it, Photographers Formulary do list it but it comes as a liquid, not a powder, I'm confused. Is Ammonium thiosulfate just sodium thiosulfate in liquid form?

 

[Ian Grant]

Ammonia is a silver solvent, so Ammonium Thiosulphate based fixers act more rapidly, hence Rapid fixers. Sodium Thiosulphate based fixers act much slower, around 5x approx.

Adding Ammonium Chloride alongside Sodium Thiosuphate creates Ammonium Thiosphate so again a rapid fixer.

Ian

 

[koraks]

for some reason, never mixed my own fixers.

The reasons might be: convenience and marginal cost advantage of DIY mixing.

Photographers Formulary do list it but it comes as a liquid, not a powder

Good. You don't want a powder anyway, since it's quite hygroscopic and when it gets wet (which it will, it's hygroscopic), it breaks down into a.o. elemental sulfur. If you then use this material for making your own fixer, it'll have an undissolvable sulfur sludge in it which can create a little fog by forming silver sulfide with unfixed silver halide, although you may not even notice this. To get a clean fixer, you'll have to filter the solution.

An ammonium thiosulfate solution (typically ~60%) is stable and clean.

Ammonium thiosulfate (solution) is sometimes sold as a liquid fertilizer; it's probably the cheapest way to get it, but you may have to deal with fairly large quantities of at least a few gallons. It may also be hard to obtain for a non-commercial purchaser.

@Ian Grant 's suggestion of using easily available sodium thiosulfate in combination with ammonium chloride can work, too, but personally, I don't bother and just buy my fixer as-is.

 

[pentaxuser]

.
The problem is I cannot find a supplier for ammonium thiosulfate, the two places in Australia that sell photo chemicals, VanBar and Gold Street studios don't list it, Photographers Formulary do list it but it comes as a liquid, not a powder,

Maybe reach out to other members from Oz in case they mix their own and know of a stockist? Best of luck

pentaxuser

 

[cmacd123]

ammonium thiosulfate is apparently very hard to disolve, so it is Generally only sold as a liquid solution. for the same reason, "Rapid Fixer" is also supplied in Liquid form. I do remember my Jaw dropping the first time I got some Rapid Fixer back in the 1960s (Proably "May and Baker" brand) and establisheing a fixing time at Under 2 minutes. for years the brand I could get was "Edwal Quick Fix" and these days it is Ilford Rapid Fixer.

 

[john_s]

I used to mix fixer using sodium thiosulphate and ammonium chloride and it was quite good. These days I mix my own developers for very good reasons, but there are fewer reasons to mix fixer. I too have looked for ammonium thiosulphate and there's plenty of it mixed with other fertilizer components, but I gave up.

 

[koraks]

ammonium thiosulfate is apparently very hard to disolve

It's in fact very easy to dissolve. Easier than sodium thiosulfate. See my earlier post above why it's generally sold as a liquid.

 

[tokam]

John Finch, (Youtube Pictorial Planet), shows how to make AGFA 304 Rapid fix from:
Sodium Thiousulphate
Ammonium Chloride
Potassium Metabisulphite

I priced the chemicals from Vanbar to make 5 litres of rapid fix and it does come out slightly cheaper than buying Ilford Rapid fix which around Sydney is around $30 - $34 for one litre of concentrate.. Sourcing Ilford Rapid Fix in Sydney is problematic at the retail level. Stores that list it on their websites are frequently out of stock. Freight from Vanbar in Melbourne is not cheap for liquid chems.

The main reason that would push me to make my own 304 Rapid fix is that I rarely use a full bottle of Ilford Rapid Fix before the concentrate has expired and started to get lots of particles in suspension. I usually have to throw out the last fifth of the bottle or more. ( I use it 1 + 4 for film use only). Making my own 304 fix from dry chems should mean less wastage. The most expensive component from Vanbar is the Sodium Thiosulphate at about $22.00 per Kg. Sure that I can find much better prices buying in bulk from pool supply stores etc.

 

[Ian Grant]

ammonium thiosulfate is apparently very hard to disolve, so it is Generally only sold as a liquid solution. for the same reason, "Rapid Fixer" is also supplied in Liquid form. I do remember my Jaw dropping the first time I got some Rapid Fixer back in the 1960s (Proably "May and Baker" brand) and establisheing a fixing time at Under 2 minutes. for years the brand I could get was "Edwal Quick Fix" and these days it is Ilford Rapid Fixer.

Quite the opposite Ammonium Thioulphate is hydroscopic, it absorbs water which makes storage in crystal form problematic, so it's sold as a liquid concentrate.

Ian

 

[pentaxuser]

tokam's post made me want to look at the John Finch video again. It is an easy fixer to make but John recommends it is used as stock for films and mentions 10-20 max films. When the clearing time doubles that his sign to dump it

John say it will do about 30 8x10 sheets of paper. It doesn't seem to last as long as say Ilford Rapid Fixer which has the added advantage of using 1+4 for film and 1+9 or paper

So it would seem to be a matter of weighing up the cost of this fixer versus Ilford 1L on the basis of equal throughput of film or paper plus the added advantage of not being dependent on the supply of Ilford

pentaxuser

 

[cmacd123]

Quite the opposite Ammonium Thioulphate is hydroscopic, it absorbs water which makes storage in crystal form problematic, so it's sold as a liquid concentrate.

Ian

so it is hard to disolve "accurately" I will go with that..

 

[koraks]

so it is hard to disolve "accurately"

Not really. I think I've outlined the reasons pretty clearly in #3, based on hands-on experience.

 

[Ian Grant]

so it is hard to disolve "accurately" I will go with that..

Yes, if you don't know how hydrated the crystalline AmmoniumThiosuplate is you can't make up an accurate solution.

Ian

 

[john_s]

Yes, if you don't know how hydrated the crystalline AmmoniumThiosuplate is you can't make up an accurate solution.

Ian

I have some stock chemicals which have hydrated themselves to various degrees (and with luck haven't changed their composition by absorbing atmospheric CO2, maybe O2). I dissolve an accurately weighed amount in a small amount of water and measure its density. Using the density graphs at engineering toolbox website I can get close to the true concentration, then do some arithmetic.

 

[pentaxuser]

I have some stock chemicals which have hydrated themselves to various degrees (and with luck haven't changed their composition by absorbing atmospheric CO2, maybe O2). I dissolve an accurately weighed amount in a small amount of water and measure its density. Using the density graphs at engineering toolbox website I can get close to the true concentration, then do some arithmetic.

I presume the easiest way to avoid having to do this is to prevent the crystals hydrating in the first place. So assuming weight of the crystals are correct on opening for the first time. how do you go about maintaining a constant level of hydration. Would placing dessicant bags in with the remaining crystal work sufficiently well and if not, what else is available?


pentaxuser

 

[john_s]

I presume the easiest way to avoid having to do this is to prevent the crystals hydrating in the first place. So assuming weight of the crystals are correct on opening for the first time. how do you go about maintaining a constant level of hydration. Would placing dessicant bags in with the remaining crystal work sufficiently well and if not, what else is available?


pentaxuser

Of course.

But retailers of loose photo chemicals have opened and closed containers sometimes for quite a while. Some chemicals absorb atmospheric moisture very readily.

And after I store the chemicals in glass, I still open them from time to time. I assumed that it wouldn't make much difference, and it doesn't much of the time, but it can.

 

[koraks]

But retailers of loose photo chemicals

Now I see an old pharmacy in my mind's eye, with glass stoppered jars in a cabinet behind a man in a lab coat..."g'day sir, I should very much like to purchase from you two dozen grains of hydroquinone for the development of my glass plates, please".

I reckon the remaining handful of retailers of "loose" chemistry work in similar ways - i.e. they receive a jar/bag/tub of whathaveyou, repackage it into the two or three sizes they list on their website and that's it. Maybe they'll split out a couple of the bigger sizes into smaller ones, or vice versa, depending on how demand develops. I don't think they'll sit around waiting for your order to take that big glass jar off the shelf, and...etc. Not unless they're an amateur photographer with a little ebay chemistry trade on the side, and even they will generally work in batches. It's a lot more efficient that way.

 

[pentaxuser]

Of course.

But retailers of loose photo chemicals have opened and closed containers sometimes for quite a while. Some chemicals absorb atmospheric moisture very readily.

And after I store the chemicals in glass, I still open them from time to time. I assumed that it wouldn't make much difference, and it doesn't much of the time, but it can.

Does this mean that keeping moisture out in the case hydroscopic chemicals isn't important and that dessicant packets are of no use or simply are unnecessary?

pentaxuser

 

[john_s]

Now I see an old pharmacy in my mind's eye, with glass stoppered jars in a cabinet behind a man in a lab coat..."g'day sir, I should very much like to purchase from you two dozen grains of hydroquinone for the development of my glass plates, please".

I reckon the remaining handful of retailers of "loose" chemistry work in similar ways - i.e. they receive a jar/bag/tub of whathaveyou, repackage it into the two or three sizes they list on their website and that's it. Maybe they'll split out a couple of the bigger sizes into smaller ones, or vice versa, depending on how demand develops. I don't think they'll sit around waiting for your order to take that big glass jar off the shelf, and...etc. Not unless they're an amateur photographer with a little ebay chemistry trade on the side, and even they will generally work in batches. It's a lot more efficient that way.

Well, Vanbar in Melbourne (a very major supplier to the photographic industry) to some extent still pack up chemicals to order.