Thank you for your advice. I never used copper salt and adhesive
when fusing. I would be interested in learning more about this
method. When I was studying we were taught to make the area to be
fused flush and clean and enriched. How would I use the adhesive
and copper salt?
This is the classical technique for fusing high-karat gold. The
technicalities of the process were rediscovered by Patricia Davidson
and published in the catalog of an important exhibition of ancient
jewelry presented in Boston, New York and Richmond in 1965-66.
In brief, a preparation of a copper salt and an organic adhesive
dissolved in water is used to adhere the pieces together before
placing in the fire. As the pieces heat the adhesive burns, releasing
it’s carbon and creating a reducing atmosphere. The freed carbon
reacts with the copper salt combining with the non-copper ions,
essentially smelting the salt. The freed copper now combines in a
molecule thin layer with the gold creating a surface of slightly
lower carat and thus one that melts at a lower temperature. Now the
pieces will melt at the surface and fuse well before the body of the
pieces reach their liquidus.
This technique is used today for the production of granulated
jewelry, but in the ancient world, before the invention of soldering,
it was how all gold jewelry was made.
The catalog of the exhibition is out of print, but is often
available used from Amazon or even your local used bookseller.
Greek Gold: Jewelry from the Age of Alexander; Herbert Hoffman and
Patricia F. Davidson; von Zabern, 1965