I have to do this for a jeweler that I make belt buckles for. I clean
the silver on the side that goes to the copper using fine steel
wool…usually on a split mandrel on the buffing machine. Use a hard
solder flux (batterns brand is what I use) and coat the side you
cleaned. Now put some nippits of solder on the piece and let it flow.
Pickel the silver & rinse well. Clean it again with steel wool. Clean
the copper where it is to be soldered with the steel wool. Aviod
touching the cleaned areas with your fingers. Use clean steel wool.
Put some flux now on the silver & the copper just where the piece
will be soldered. Put the silver on the copper piece and make sure
the contact between the two is real good. Heat the thickest piece
first… then begin to heat evenly. The solder should flow easily
now. Pickle & clean up!
I would not use the boric acid. I know it takes more clean up without
it but the boric acid can sometimes do strange things. Especially
with the copper. I typically ues boric acid only with Gold. Hope this