have found an otc source for sodium dithionite (aka sodium hydrosulfite) as a fabric dye remover. wee problem though. In its current formulation it is blended with a small amount of Sodium Carbonate.

its possible that the Sodium Carbonate might not affect the redxn, as this formulation is for reducing dyes, but don't know for sure. wouldn't it be nice though if there were some way of isoating the sodium dithionite. I f i had more acess to solubility data on the salts maybe there is a solvent  extraction or something. I am entirely opn to suggestions. Ideas bees?

Sodium carbonate decahydrate is soluable in 2 parts cold water.(1 gram per 2 grams water)  Sodium dithionate dihyrdrate's solubility is 6.05% w/w in water at 0C.(1 gram per 16.5 grams of water)

Do you have any idea of the proportion of each?
One problem is the pH of sodium carbonate solution is 11.6 so who knows how that affects the dithionate solubility.  My guess is that dissolved sodium carbonate will lower the solubility of dithionate.

I'd try washing with ice cold water.

In its current formulation it is blended with a small amount of Sodium Carbonate.

If thats the case washing should work.

"Exposure to small amounts of water causes spontaneous ignition, and the resulting decomposition causes sulphur dioxide to be released They are easy to dissolve in water."

Bee careful mixing with water.

http://www.basf.de/en/produkte/chemikalien/anorganika/schwefel/blankit_marken.htm?id=V00-%2AP2VZXf%2A%2Absf700

http://www.basf.de/en/produkte/chemikalien/anorganika/schwefel/hydrosulfit_p_fluessig.htm?id=V00-%2AP2VZ_c%2A%2Absf100

Post 429965

(lugh: "Inorganic Syntheses", Chemistry Discourse)