I just ran some ball for my muzzle loader today and had to scrap about 10lbs of alloy.

Anybody run into the situation where a thin metallic scum forms on the top of the melt, almost like a layer of foil? Also, as the level of metal in the pot went down, the drossing rate went way up. The balls started coming out of the mold a tan color and by the time I gave up, they were purple. The pour spout on my pot also started plugging quicker than I could keep it clean.

Not a big deal but wondering if anyone had an idea of what mix would cause this? I don't think it was zinc as it wasn't "slushy".

my guess is that the plugging of the spout and the pretty colars came from using an alloy that is near pure. Your probably getting less as the pot gets lower because usually a half empty pot will be hotter then a full one. Try turning your heat all the way up and im sure the problems will diminish. As to the dross as long as your gettting good fillout after fluxing and skimming i wouldnt worry about it.

I suspect the "dross" you are seeing may be lead oxide. I would flux the pot very well to remove impurities, then do as Lloyd said. And I am also in agreement that purple bullets are indicative of very pure lead, combined with high temperature. That is a good thing!

Hmmmm....

Thanks for the posts. The stuff is SOFT, registering at or under 5bhn with a Lee tester (chart extrapolated).

I would have used the final 10lbs but was having a terrible time getting fillout at the scale buildup at pour was such that it'd block flow. This same scale was what was plugging the pour spout. Just had the thought... might try a dipper?