Any alloy, or technique suggestions would be greatly appreciated.
Considering the fuss and bother and aggrevation you go through when
a casting turns out crappy, why not just send the scrap to any decent
refiner, asking to get the appropriate new casting grain in return.
Find one of the refiners that does not charge a set lot refining fee,
such as David Fell. They pay in the mid 90 percentages for the gold
content, then of course charge you a bit over the spot price for the
new alloy. But I think you’ll find that the added cost of not using
all scrap will be quickly paid back in the better castings. Remember
that you usually can use a mix of old CLEAN scrap and new metal with
equally good results. Just be sure the old metal is metal without
inclusions, solder, etc, which itself produced decent castings the
last time it was cast. That way, you buy new metal as needed, mixing
the new with the old buttons and sprues, and don’t end up with only
old messed up metal.
You’re right about white golds being fussier. In my experience,
attempts to revive significantly junked up white gold scrap end up in
failure more often than not. Once it’s casting into porous or overly
hard, cracky, brittle or otherwise unacceptable castings, it’s better
to scrap it out and save yourself the trouble of trying to rescue it,
since those efforts generally don’t work so well. The percentage paid
by refiners for the gold content when what you’re sending is clean
scrap for which you only wish to be paid for gold content, rather
than mixed precious metals, is high enough that simply scrapping the
unacceptable metal is much more cost effective.