Sorry I let Paul’s post slip by. Mitch Adams has my formula
absolutely right. Oven at 400 F. The polished copper will first turn
orange, then a sort of magenta red. The orange is not very durable,
but the darker magenta holds fairly well. Depending on what you use
to clean your work, you may have some residues that will prevent this
from happening cleanly. My ultrasonic solution seems to be a problem,
so I have to wipe with alcohol after cleaning. Straight out of the
tumbler with RIO’s 910 burnishing compound works just perfect. If you
over heat, or heat too long it starts to turn brown and icky. If that
happens, pickel and try again.
A light coat of wax (I use car wax) will keep the finish longer, but
it does take the intensity off the color slightly. Since that very
vibrant color does not last and will mellow into a more natural,
browner patina with handling, I feel it is better as far as keeping
the customers expectations realistic. It can last for years or turn
brown in a few days, depending on perspiration, light, care and
personal chemistry. My care card describes how the patina will mellow
with time and makes care suggestions along the lines of benign
neglect, since this sort of material looks better if it is not
polished too often. All you have to know is that “tarnish” is a dirty
word, but “patina” is an art word!
Steve Walker