Try Bryant Labs in Berkeley, CA 800-367-3141
This is where I get all my patination and etching chemicals. I
order Ferric Nitrate in 5lb jars. Make sure you keep the lid closed
very tight, as it will suck up water like a sponge. I throw one of
those packets of silica dessicants that I find in packages of candy.
Use one cup of ferric nitrate to three cups of water. You want the
solution to look like strong tea. Etch the same as ferric chloride.
When you are through with the solution, pour it into some kitty
litter and bag it up. Easier to recycle that way.
One tip, use DISTILLED water. Also, make sure that your silver is
VERY clean. Try to touch it only by the edges after cleaning.
M E T A L W E R X
50 Guinan St.
Waltham, MA 02451