who can shed some light on the following question. Sparex I understand
to be sodium bisulphite.
I suspect it’s bisulphate, not bisulphite. I’ve not used it but I
could imagine that sodium bisulphate (which is very acidic) would be
a useful replacement pickle for sulphuric acid. Bisulphite, on the
other hand, is a weak reducing agent - not acidic at all.
Recently I ran out, and since the nearest supplier is a few hours
drive away, and not wanting to raid the battery acid as I’ve also done
on occasion, I asked around and found I could get sodium
metabisulphite at the local wine and beer-making supply store. They
sell it as a disinfectant. The salesclerk told me that an
industrial-scale gold jewelery manufacturer in this area buys it there
My question is, is there a substantive chemical difference between
sodium bisulphite and sodium metabisulphite,or is it merely a matter
of terminology, one term being perhaps more chemically correct than
the other? If in fact there is such a difference, how might this
affect the pickling process?
Er, no, they’re different. Very different. I suspect you wouldn’t
get a pickling action but the reducing properties might do something.