Is it Me or the Alloy

[RogerDat]

Found these RCBS ingots at the recycler. Decided to melt them because they were covered with white oxide and I wanted to store nice clean ingots.

They did not want to melt or stay melted, at 700 degrees still kept forming a skin with sort of a colored tint. Sawdust burned off scraped pot and skimmed and few minutes later had more tan/gold dust on the top. Not heavy so I don't think I was removing "good" metal, figured maybe I did not get all the sawdust out but wanted to get opinions of more experienced folks.

Ingots came out very shiny but with heat discolored patches. Mold was cool.

Note the layers in the one on it's side and the globby bottoms. Melted in layers too, had to push and break them up to get them to melt.



This image is just an expression of lust and desire, that is a 6 inch board sitting on three really large chunks of lead. Hard to scratch with fingernail so probably not plain, seem like a base weight, with a hole through the center. I'm scheming even as I type how to acquire.

[RogerDat]

I was hoping
A). That someone could tell me if that tan stuff that kept coming up to the top was likely sawdust ash.
B). Any ideas on what would make lead need to be 700 or more degrees to keep from getting a skin on the top.
C). What would cause a gold colored skin or slick to form on the melt.
D). What would cause ingots to be shiny with areas of heat discoloration.

It's not enough lead that I'm going to worry about it, maybe 10# but I am curios and it's the second time I tried sawdust, the first time melt was too cold and sawdust did not burn off properly according to member assessment of pictures.

BTW scheming in this case means coming up with the money to purchase and way to transport. Nothing illegal or immoral (well wife sometimes thinks money I waste on hobbies is immoral but...)

[glicerin]

Badly oxidized or painted alloys can be very slow to melt. The oxides can be tan, gold, blue. Try different fluxes-paraffin, beeswax, sawdust. White powdery oxide on ingots usually means high lead content. Alloys with tin, antimony, zinc seldom oxidize like that. When I had zinc once, the surface looked like oatmeal(so that's probably not your problem). Ingots with high tin content sometimes have a gold-yellow tint(good stuff).

[RogerDat]

Thanks glycerin,
That stuff was covered in white oxide, I was concerned because I recalled reading lead oxide is more likely to get into your body through breathing or getting transferred through contact than lead itself.

Had no idea it would act that different when melted. Of course the stuff I have melted to date has all been alloy with at least some tin so I guess that was why this seemed so different.