Caustic Soda / Lye / Sodium Hyrdroxide
I need some Caustic Soda for my next Instructable, and I've found a drain-cleaning product with Sodium Hydroxide listed as the main ingredient. (Potassium Nitrate as the second, yay!) Is there any way to measure the purity of any of the ingredients?
Does anybody know of a better source of lye? (As it's kind of a pain to sift out the pellets of saltpeter from the mix.)