I’ve been depletion gilding 14KY gold for years and never had a
problem before, but I’ve got one now. A friend offered to do some
casting for me of a piece I’d created; this was a first for me since
I usually fabricate everything. I supplied the gold which was clean
scrap – 14KY with perhaps a little 18KY thrown in, but definitely no
other or lower karat metal.
The resulting five replicas were quite pale; they looked almost like
14KW. I decided to depletion gild them so they would look more
yellow. Five cycles of heating/quenching later and they all still
looked like a very pale 14KY; there was no appreciable change.
I asked my friend if anything could have contaminated the melt,
especially considering that he had done the casting in a class where
other people use the equipment. He said the crucible was designated
for gold use only though it wasn’t impossible someone had used it to
cast silver; but he said that it certainly looked clean when he put
the gold in it.
Did something go wrong during the casting process? Could a
clean-appearing crucible hold enough of a residue to explain such a
result? Or is it just not possible to depletion gild cast gold and,
if so, why would that be?