Anynone seen this before?

[mfenton]

I have a problem, As I melted down a 5 gal bucket of wheel weights a couple of batches were contaminated with a almost virus type phenomenon. A gold sludge formed on the top which then turned purple. When dragged the sludge off bright silver appeared as though I was down to good metal. However within seconds the sludge appeared again. After repeated efforts and varying the temp the metal was contaminated to the end.
I melt initial metal in a cast iron pot and make clean ingots. I have melted some of these ingots in my Lee pot, which had had some contaminate in the past but I emptied the pot sanded the sides and generally cleaned up, but when I melted the good ingots the residue left in the pot seemed to contaminate the entire good ingots, like a virus.
Has anyone ever experienced anything like this?

[fishhawk]

It's not contaminated, It's just to hot and that oxide forming on almost pure lead.

[500MAG]

The gold is tin and the purple is pure lead. Throw some sawdust in and flux it back in. Try to keep your temp below 750.

[John Allen]

The temp is too high. Your tin is coming out.