Oxali Acid is "wood bleach." We use it all of the time in our shop, but can be purchased cheaply at any store that sell products for cleaning wood; decks,etc. You have to be carefull when purchasing it as a "deck brightener," as it may not be pure. We buy it in 5# canisters, but I just saw it at a local hardware store packed in a 1# tub by "DAP<" it is labeled simple "Wood Bleach." Hope this helps...BTW< made my own evaporator, and will try it tonight...JK :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::