Kathy,
You might try Sculpt Nouveau. It is owned by Ron Young, a long time
bronze caster and teacher whose specialty is restoring patinas on old
bronzes. He’s developed a line of bottled patinas that save the
artist the trouble and expense of storing a lot of chemicals in the
studio. Ron and his wife Debby are fountains of knowledge which they
readily share.
But understand that few copper patinas are “tried and true”. They all
require experimentation and huge amounts of patience. Copper patinas
can be fickle. The results will often vary with heat, humidity, time,
and method of application. So be willing to use any ready made patina
with this in mind, and expect some variation from the colors in the
catalogue.
Good luck!
Rene Roberts