Generally, scrap contains so much solder etc. that you don’t get
good results. You get porosity in casting and all that "fraying"
in fabrication. Not to mention the fact that the resulting piece
is of indeterminate karatage. If your business requires you to
use scrap, you might suggest adding refined gold to the mix,
ideally 50-50. It seems to me trying to refine the customers
scrap would be too costly and time consuming and you couldn’t
charge for it. You might give the customer “credit” for their
scrap toward some fresh alloy. Anybody else have any ideas?
Over the years I’ve had plenty of ocaisions to use old gold. It
only scares me when I don’t know what quality metal I am working
with. In particular, I try to keep out white gold dental golds.
Otherwise, if cracking starts, I will bring the metal to a nearly
white heat and cook out most of the zinc. I don’t know what else
might bev burning out, but if I add zinc to the resulting mass
the color and quality seem to improve. If the metal is for
resale, it probably is a real good idea to just refine it when a
few ounces have accumulated and alloy new metal as needed. In my
book, pitting is not a result of poorly alloyed or impure metal
so much as too hot a flask or improper spruing. Furthermore,
virtually all pitting can be removed with a rotary burnisher.
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