Quote Originally Posted by jnanian View Post
hi mark

can you get baking soda ?
baking soda is washing soda but with more water absorbed
into the powder.
if you put some in a oven at a low temp you can evap the moisture out of it
and convert it to washing soda.
i can't say much about the potassium stuff never used it ..

good luck !
Baking soda (sodium bicarbonate) and washing soda (sodium carbonate) aren't just different because of more/less absorbed water. That's the difference between anhydrous/monohydrate/decahydrate forms of sodium carbonate. They're different compounds.

But jnainan is correct that baking soda will decompose on heating, slowly, starting at 70c, more quickly at 200c, into the anhydrous form of sodium carbonate. Left open after cooling, it will eventually absorb some water and convert to the monohydrate form, the most stable.