Time to dissolve selenium

Xícara · Dec 13, 2023

Hello,

I'd like to make the direct selenium toner "Dassonville T-55" (Formula #162) detailed in the Darkroom Cookbook (3rd ed.). The first step involves mixing the sodium sulfite in 100ml of warm water. The directions then say to add the selenium and "slowly heat" until dissolved. I was uncertain about much heat would be needed but saw in another thread on this forum that the solution needs to be boiled and that the boiling can take "a couple of hours". Is that really the case? If I were to start with just 100ml of water, I imagine that it could easily boil dry in that time, so I suppose I'd need to keep topping it up with more water.

The thread I saw was this one: https://www.photrio.com/forum/threa...dak-selenium-toner-formula.96284/post-1278543

I'd rather buy selenium toner off the shelf but here in Brazil it's quite expensive (almost R$800). I can make a lifetime supply if I wish for a fraction of the cost.

Thanks. All the best,

Saganich · Dec 13, 2023

I can believe it. How about Sodium Selenite powder? Dissolvable in water. No boiling required. Anyway if your going to boil selenium power for an hour it's best done in a fume hood.

Xícara · Dec 13, 2023

Saganich said:
I can believe it. How about Sodium Selenite powder? Dissolvable in water. No boiling required. Anyway if your going to boil selenium power for an hour it's best done in a fume hood.

That would be excellent. So the sodium selenite substitutes the selenium? Would it be a gram for gram substitution?

Anon Ymous · Dec 13, 2023

Xícara said:
That would be excellent. So the sodium selenite substitutes the selenium? Would it be a gram for gram substitution?

Lookup the Kodak Rapid Selenium Toner MSDS. Perhaps you could try concocting something, assuming that you can source sodium selenite (and sodium sulfite, ammonium thiosulfate). I personally wouldn't try boiling selenium powder, it's just too risky IMHO without proper lab gear.

Xícara · Dec 13, 2023

Anon Ymous said:
Lookup the Kodak Rapid Selenium Toner MSDS. Perhaps you could try concocting something, assuming that you can source sodium selenite (and sodium sulfite, ammonium thiosulfate). I personally wouldn't try boiling selenium powder, it's just too risky IMHO without proper lab gear.

Thanks and yes, all these compounds are available. The Kodak Rapid Selenium Toner MSDS gives the composition as:

Weight percent	Components - (CAS-No.)
25 - 30 10 - 15 1 - 5	Ammonium thiosulphate (7783-18-8) Sodium sulphite (7757-83-7) Selenious acid, disodium salt (10102-18-8)

Another post ( https://www.photrio.com/forum/threa...dak-selenium-toner-formula.96284/post-1278557 ) gives the following formula derived from the "Kodak MSDS":

- - - - - - - - - - - - -

Water, dist. 560 ml
Ammoniumthiosulfate, sicc. 270 g
Sodiumsulfite, sicc. 150 g
Sodiumselenite 20 g

In contrast to common photographic formula it is not filled up with water to 1000 ml.

- - - - - - - - - - - - -

Does this last formula look correct?

I don't know what "sicc" stands for. I assume that the sodium sulfite does not need to be anhydrous.

Would it be correct to create this mixture in water at around 55°C?

EDIT: All the sodium selenite available is anhydrous. Is that fine?

EDIT 2:

Judging from other formulas, how does this approach sound? :

1. Heat distilled water to 55°C
2. Dissolve the sodium sulfite
3. Dissolve the sodium selenite
4. Let cool to room temperature
5. Dissolve the ammonium thiosulfate

Anon Ymous · Dec 13, 2023

Xícara said:
Thanks and yes, all these compounds are available. The Kodak Rapid Selenium Toner MSDS gives the composition as:

Weight percent Components - (CAS-No.)

25 - 30 10 - 15 1 - 5 Ammonium thiosulphate (7783-18-8) Sodium sulphite (7757-83-7) Selenious acid, disodium salt (10102-18-8)

Another post ( https://www.photrio.com/forum/threa...dak-selenium-toner-formula.96284/post-1278557 ) gives the following formula derived from the "Kodak MSDS":

- - - - - - - - - - - - -

Water, dist. 560 ml
Ammoniumthiosulfate, sicc. 270 g
Sodiumsulfite, sicc. 150 g
Sodiumselenite 20 g

In contrast to common photographic formula it is not filled up with water to 1000 ml.

- - - - - - - - - - - - -

Does this last formula look correct?

I don't know what "sicc" stands for. I assume that the sodium sulfite does not need to be anhydrous.

Would it be correct to create this mixture in water at around 55°C?

EDIT: All the sodium selenite available is anhydrous. Is that fine?

EDIT 2:

Judging from other formulas, how does this approach sound? :

1. Heat distilled water to 55°C
2. Dissolve the sodium sulfite
3. Dissolve the sodium selenite
4. Let cool to room temperature
5. Dissolve the ammonium thiosulfate

Sicc means anhydrous. A common source for ammonium thiosulfate is the 60% w/w solution. Thus, you would need 450g of this solution, which has a density of about 1,33g/ml. This means about 340ml. You are now at 900ml. Add the rest of the ingredients and you'll get closer to 1l anyway. I wouldn't start at 55°C, more likely near room temperature, or a bit warmer. If necessary, I'd heat until everything dissolves (I have some borosilicate glass beakers, so it's pretty easy for me). But truth be told, I have no idea what a "proper" addition order is for this formula, nor if there is one.

Whatever you do, be very careful with the selenite.

Xícara · Dec 13, 2023

Anon Ymous said:
Sicc means anhydrous. A common source for ammonium thiosulfate is the 60% w/w solution. Thus, you would need 450g of this solution, which has a density of about 1,33g/ml. This means about 340ml. You are now at 900ml. Add the rest of the ingredients and you'll get closer to 1l anyway. I wouldn't start at 55°C, more likely near room temperature, or a bit warmer. If necessary, I'd heat until everything dissolves (I have some borosilicate glass beakers, so it's pretty easy for me). But truth be told, I have no idea what a "proper" addition order is for this formula, nor if there is one.

Whatever you do, be very careful with the selenite.

Thanks again.This is very helpful. I was mistaken that I'd found ammonium thiosulfate. I believe I've found some fertilizers that have it in solution (80%) but need to check that these products don't contain other things and where to buy. Some other selenium toner formulas use ammonium chloride. This I can find, but of course, I don't know if it's suitable for this Kodak formula. I will keep looking into ammonium thiosulfate.

edit: ammonium sulfate is easy to find

Anon Ymous · Dec 13, 2023

Xícara said:
I believe I've found some fertilizers that have it in solution (80%) but need to check that these products don't contain other things and where to buy.

They typically contain some ammonium sulfite and perhaps some ammonium sulfate. I doubt they can cause any problems. Sodium sulfite will oxidise to sulfate sooner or later anyway, so some sulfate will inevitably form.

And if you dind this solution, you also have the basic ingredient for your rapid fixer.

Time to dissolve selenium

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