Hi, I saw this happen when a student, at the Argentium Sterling
workshop that I taught at Metalwerx, was soldering a post onto an
earring. The problem was that the self-locking tweezers that were
being used to hold the wire had too strong a tension/grip, and when
the Argentium Sterling got hot, the tweezers broke the wire. The
solution in that case was to use a pair of tweezers that did not
squeeze so tightly. Let us know if this solves the problem!