Does anyone have any guesses what might have been in my crucible? I
was melting a students metal. Should have been sterling silver, but
a couple of things happened which made me doubt this alloy. First,
the melt was much brighter than normal. Almost painfully white hot.
Next, there was a slag. Not heavy, but enough to bother me. The
student told me the crucible had contained nothing but sterling
silver buttons. When I spun the arm, some of the metal flew out of
the crucible, some went in, but what was left behind was a
purplish-black coating on my crucible. Not the red-purple color, but
black. I told the student his metal must have been contaminated. But
he said it was impossible. Can I use this crucible again? It was a
new one, and I need to cast more students work.