Originally Posted by
Prism99
Alum would be in the spice section of the grocery store. My mother used to use it in a few recipes -- baking, I think. It's a white powder. Not sure what quantity would be required for photos, though. Typically you buy alum in one of those undersized spice containers that hold maybe a couple of ounces.
Found out today the alum is used in pickle making to keep them crisp !!!