Mark, You can go about this in two ways. The resist can be applied in
the form of asphaltum or a product called PnP Blue. PnP Blue or
"Press n Peel" was used in the printed circuit industry. It is
basically a low tech process which involves nothing more than an
application with heat to transfer your image onto silver. Your iron
set a low temperature works great.
You can use two mordants. One is nitric acid and the other is ferric
nitrate. Both will work with PnP Blue. Ferric nitrate is available
from Bryant Labs in Berkeley. It is a slower etch, meaning several
hours, but it is crisp and precise. Search the Orchid Archives for
my treatise on this.
M E T A L W E R X
10 Walnut St.
Woburn, MA 01801
Accredited Jewelry Instruction