help-What do I have here?

[BMac]

This is from a batch of coww. % 10 stickons and the rest coww. I've never had this issue before,but this time I had the lid on while I brought the pot up to temp, so I'm thinking zinc?

[BMac]

This is from a batch of coww. % 10 stickons and the rest coww. I've never had this issue before,but this time I had the lid on while I brought the pot up to temp, so I'm thinking zinc?

I should add that I pulled out about 2 muffin tins of oatmeal type ****, approx 1/2 the density of lead.
also, this batch was batch 2 of 3 and the only one having issues.
I able to cast, the alloy does not really "frost" when cast really hot, it fills out pretty good.

[Danderdude]

You overheated it. Zinc contamination will actually change the consistency of the melt to something closer to juicy outmeal.

Overheating the melt will cause relatively rapid oxidation of the surface, and it'll go from shiny, to matte, to straw gold, to blue to deep purple as the depth of the oxidation increases.

Flux it to reduce the oxides back to pure metal and let some hot carbon carry off the extra oxygen.

[williamwaco]

The only thing I have had any success with is fluxing with sawdust two to three times.
Wax will not help.