selenium toner: the fool's gold toner

[IanG]

{QUOTE=Andrew O'Neill;1324294]I wonder if one could use KRST instead of selenium powder....[/QUOTE]

No.

You should use a fum cupboard when dissolving Selenium powder in a Sodium Sulphite solution, it also needs heating. It's quite an old Selenium Toner formula there's a few variations but they work well.

Ian

[Andrew O'Neill]

Thanks, Ian. I'll pass. I'm avoiding tricky stuff like that in my darkroom.

[olive92]

Hi,

OK the formula is finally confirmed by this link:

http://www.bostick-sullivan.com/blog/?cat=38

I've prepared 100 mL of it with:

0.6 g selenium powder
7.5g sodium sulfite
100 ml of water

The selenium takes about 45 minutes to solve in the sodium sulfite solution at boiling temperature.

I have use a hood to avoid to breathe toxic emissions.

Bye

Olivier

[koraks]

I'm looking forward to the results!

[Duolab123]

Be careful, I used to handle Sodium Selenite at a plant. We were very careful. I actually think (but don't know) that Selenium metal powder is less toxic than the water soluble salts. Remember when dealing with very finely divided powdered metals, these things in the presence of an oxidizer can react violently. 0.6 grams sounds pretty safe to me.

[koraks]

I think it's good practice to work with small volumes. I'll probably be ordering some selenium powder in the short term for toning purposes.
Something I'm wondering about though: does it disperse easily in water? I mean, I assume it's not actually water soluble, so I'm kind of surprised that this formula apparently uses metal selenium instead of a salt - although that's true for all selenium toner recipes I've seen.

[Duolab123]

I finally found a text on Selenium. The element is not a metal. It exists in 3 allotropes, the most common is the little black beads, (this is how I've seen it in a lab). Elemental Selenium is very Insoluble in water. It could be that the sodium sulfide reacts to dissolve the Se? I'm not sure.
The salts are similar in toxicity to certain arsenic compounds. I've used the prepared Kodak product for decades I tone everything.
Best Regards Mike

[Duolab123]

Sodium sulfite , not sulfide

[BarryS]

I ordered the Fool's Gold toner from B&S when it was available and never liked it much. There were issues with bleaching and uneven toning. Your results may differ, but there's probably a good reason they no longer offer it.

[olive92]

Hi,

yes duolab123 the selenium is not soluble in water but it dissolves in the sodium sulfite solution to form a sodium selenosulfate (as the reaction of sulfur with sodium sulfite produces sodium thiosulfate).
I think it's the selenosulfate which permits the toning process.

I don't know why B&S stops to offer it. Perhaps because of the toxicity of selenium...

The toxicity is one of the reasons why i only make 100 mL of stock solution because with the original formula is made for 1 liter.

Bye

Olivier