|
Hi Bojan,
Caustic soda, or sodium hydroxide, is widely available at hardware stores. Diggers is a common brand name.
However its purity may not be perfect. Do you need a pure grade for photo work? The whiter it is the better.
It doesn't self-oxidise in the chemical sense, but it is hygroscopic (attracts moisture), and then becomes aggressive, so if its surroundings were attacked it will be contaminated.
Cheers
|