Maybe someone with more sense than me can help identify this mystery froth.
Yesterday I got a package of 50 pounds linotype from a high satisfaction rating vendor on ebay. Today I started smelting it down on my homemade smelter. This gizmo is a piece of 5" circular steel pipe with a plate welded on the bottom and I put on old 5" cast iron frying pan on top to hold the heat. Put it atop my Coleman camp stove with the flame at full blast. Have smelted linotype, wheelweights, lead, all with this thing and never had a problem....until today.
This current batch leaves a silver frothy mess on top of the liquid alloy. It won't stir in, and constant application of a propane torch won't melt it. It scrapes off just like beaten eggwhites from a holiday pie. It sets up hard, so it has some alloy in it. The only time I have seen this before was from a batch of wheelweights several years ago when smelting with a Lee pot and I thought maybe some of them were some other metal. I threw that away. I have saved all this mess thinking I could salvage something from it. Have I gotten hold of zinc, or some other junk? Should I save it still and try to smelt it down some other way?
I did not flux the solid letters as I flux alloy when ready to cast.
Shoot out some ideas, I'm at wit's end!