Last night hubby and I cast eight flasks of sterling charms. We use
an Electromelt and vacuum casting equipment, and the metal was a
50/50 mixture of home-made casting grain and re-used sprue bases from
previous castings. All of the sprue bases were pickled until clean
and stored in a sealed container.
On the 4th flask, when he peeked into the electromelt to see if the
silver was liquified, he reported seeing small tendrils of black
smoke coming from the metal. From my position a few feet away I
couldn’t see the smoke. When we poured the metal and it cooled, the
visible button was a light yellow color, not the usual black of
firescale. When we quenched the flask and got the contents out, the
sprued charms were light pink instead of black. When pickled for
only a couple minutes, the sprued charms turned that lovely white of
sterling that’s been pickled for hours. The other seven flasks all
had the usual black firescale that comes off after several hours of
soaking in hot pickle.
All we can assume is that something was on/in the metal in that one
flask that prevented it from developing firescale. But we know that
none of that metal contained the alloy that prevents firescale–it’s
all home-made (fine silver with the proper % of copper added). The
only contaminant that could possibly have gotten in there was
injection wax, as there may have been tiny shreds of it on the bench
near the area where I weighed the metal.
My question is: Could a tiny bit of wax in the electromelt have
prevented the firescale? Whatever it was, we want to do that again!
Feathered Gems Pet Motif Jewelry