Anyone have any experience in cleaning zinc coins?
I have searched the
forum but have't found any old messages.
I am looking at ways to clean 17th-18th century
Vietnamese zinc cash. These are coins were made of almost pure zinc, not a Zn-Cu
alloy.
They often have a thick beige/tan coating on
part or all of their surface that looks just like hardened clay but is much harder. I believe that it must be some sort of mineralized adhesion.
Given that zinc is very soft it makes mechanical cleaning perilous - the adhesions are harder than the base metal.
SC
PS I have found lots of advice for cleaning "modern" zinc coins which have small deposits of small bits of powdery white "zinc-disease" on them. What I am looking for is different - cleaning tough thick crusts of zinc.
