Quote Originally Posted by Photo Engineer
All food grade salt (Sodium Chloride or NaCl) contains anti-caking agents which affect the imaging propreties with silver emulsions.

I have no idea what they will do for other types of photoprocesses, but I wanted to let you know that there is an extraneous ingredient in food salt, and it does affect emulsion making FYI, FWIW.

Not pickling and canning salt, it is just rock salt. They dont add anything precisely so that there are not any sediments left after the pickling or canning process.