Mason Stillwell,
Sorry to hear of your problem. Fortunately for me, I have not had your experience. I have read that if you keep an alloy just above its liquidous temperature (lowest temperature required to keep the metal in its liquid
state) that over time, impurities can rise to the surface where thay can be skimmed off.
One other thing, according to Dennis Marshall, who is a metalurgist and writes for the Cast Bullet Association, has stated that once an alloy has been made up, THE TIN , ANTIMONY AND LEAD DO NOT SEPARATE! He likened it to sugar and water. Once the sugar is disolved it will not separate from the water.
To prove this theory out, I once filled a pot with 10# of alloy and ran it completely dry without fluxing or stiring. (Do not run your pot completely empty as a standard practice or you will be replacing the heater bands more often than you want to.) The bullets weighed the same from the full pot as they did from the almost empty pot. If the metals were to separate, the bullets would have gotten heavier as the pot was depleted.
That did not happen.
w30wcf
Dross forms on the top of the melt as a result of air meeting the hot surface of the melt.