I have used alum for years. It works well. It is called aluminum alum. It is a powder you can buy at your local drug store. <<etc>>
Well, this brings up a question. All references here toalum
over the past weeks seemingly referred to “aluminum alum”. All
I can find in local pharmacies, grocery stores, and cooking
specialty stores is “ammonium alum”. The ammonium alum does
indeed pickle silver and copper-based materials, but does it do
as well? One dictionary referred to alum as “a double sulphate
of aluminum and potassium” or “a class of double sulphates
analagous to the potassium alum”. Good ol’ Sparex pickling
compound is “sodium bisulfate” – note the different spellings
Does this imply that all these are related? Are they similar in
the way they behave in solution, particularly with a piece of
metal thrown in?
Can someone with a background in chemistry explain all this so
that I, who last graced a chemestry lab nearly forty years ago,
can possibly grasp the meaning?
While you are explaining, please explain where the sulfuric acid
comes from with sodium bisulfate, and is there sulfuric acid
produced in an “alum” solution???