Does anyone know what has caused this strange phenomenon?
I put a piece of work composed of sterling, fine and a small amount
of properly fired PMC+ in the pickle and left it (cold) overnight.
The following morning the pendant was covered in a thick, matted,
greasy yellow coating.
A lot of wire brushing, several heatings and plungings into hot
pickle got rid of it - eventually.
What happened? I keep my pickle and workbenches in very clean order
and can’t think of any contaminant that might have gotten in except
maybe a little domestic washing up liquid (Dawn.)