Use hard silver solder to join the copper domes. To hide the solder
seams, submerge the piece in contaminated pickle to copper plate it.
Steel adds an electrical charge to used pickle and turns it into a
copper plating solution. If the piece is a hollow form with a small
hole, neutralize the piece and use a syringe and thoroughly rinse
inside to remove the baking soda.
Regarding Keum-boo on copper, the oxides that form on the surface of
the copper when it is heated inhibit the diffusion bond, the
permanent bond between the thin layer of gold and the copper below. I
am not an expert on bonding gold to copper. However, in my
experimentation, I have successfully bonded gold to copper, but I
have also had mixed results. I imagine it is possible to develop a
method for more predictable results. The important factor seems to be
getting the piece up to the bonding temperature quickly so the oxides
have less time to form.
Apply the patina after the Keum-boo is complete.
For more on the Keum-boo technique with gold foil on
sterling, check out my upcoming DVD series, Keum-boo Basics, The Art
of Bonding Gold to Silver, vol 1: Dangle Earrings and Keum-boo:
Beyond the Basics, Bonding Gold to a Hollow Form, vol 2: Hollow
Pendant. The series will be released this fall and will be available
through Rio Grande, AllCraft, Revere Academy and from me directly.
Revere Academy of Jewelry Arts
760 Market Street, Suite 900
San Francisco, CA 94102