We tried very hard to reproduce the results of that odd casting on
Saturday that came out of the flask pink and cupric oxide-free. We
put varying but still minute amounts of injection wax or tiny scraps
of paper (the only possible contaminants we could think might have
gotten into the first one) into the next few flasks we cast. Nothing
changed, other than we lost more pieces than usual to porosity,
probably from contamination, we are assuming. Discouraged by the
results, on the very last flask we cast, we added nothing. That
flask came out with pink spots on part of the sprue button and areas
on some of the charms (but not the entire casting). So, eight flasks
and about a 1/8 loss of the castings later, we’re no closer to
figuring out what we did than when it first happened.
In answer to various questions about our metal:
No, there’s no way it included any firescale-proof alloys. We have
never owned any of that, and we don’t melt down wire, chain, findings
or anything else that we did not cast originally. I don’t want to
risk melting down someone else’s nasty alloys, toxic metals, plating
or old solder by mistake. I don’t like inhaling toxic substances.
I’m certain that the pennies were solid copper. Zinc was first added
to the metal for American penny coins in 1982, so to be safe, we only
use pennies that were minted in 1980 or earlier. And we use marked
.999 fine silver bullion for the silver in our sterling mix, so we’re
as sure as we can be that the silver isn’t an alloy either. We
pre-melt the pennies and the bullion together, and the hot mixture is
poured into a tall 8" wide piece of heavy PVC pipe full of water to
create the actual bits of sterling casting grain (an exciting
procedure that everyone should try sometime!).
And we pour our castings as soon as the metal is thoroughly melted
in the electromelt. I couldn’t tell you the exact melting temperature
though, because the numbering on the blasted temperature gauge is so
small I can’t read it! I’ll have to check it with my Optivisor the
next time we cast…
So, there you have it. I guess we just had a tiny miracle occur in
that one flask that isn’t, at least so far, readily duplicable. Since
we don’t have a problem with actual “firescale/firestain” (apparently
I was misusing that term when referring to the more easily removed
black surface scale that is really cupric oxide), we’re not going to
worry about it. If it happens again, we’ll ponder it then.
–Kathy Johnson
Feathered Gems Pet Motif Jewelry
http://www.featheredgems.com