Mystery melt

[jeff100]

I recently purchased scrap lead from another caster who was getting out of the hobby. Included in this lead supply was a lead plate, square in shape, about 13" x 13" with a 1" (approx) hole in the center. This lead plate was about 5/8" thick. I have no idea what this plate was used for. I cut it into quarters with my reciprocating saw so it would fit in my melt pot and melted it in my melt pot. Once melted there was a heavy layer of a coarse granular looking material floating on the surface. It looked like broken clay or giant kitty litter. I stirred and mixed the material but this floating layer didn't mix in with the melted lead at all. I fluxed it heavily with sawdust several times, then skimmed off this surface layer. It never did mix back into the lead, seemed like dirt or clay. After letting this dross cool, I sifted it with my gloved hands and the material still seemed like dirt or clay, it didn't have any real weight to it nor did it have any metallic appearance or characteristic. I wish I'd taken a picture of this material but didn't. Does anyone have any idea what this material was? That lead plate I started with appeared clean although the lead was oxidized on the outside. A mystery to me.

[sqlbullet]

I get this anytime I process high surface area to weight lead, like dental foil. It is lead oxide IMHO. I have had some success geting some of it back into the melt with parafin and sawdust or used motor oil and sawdust.

I could be wrong about what it is, but that is my experience.

[jeff100]

That makes sense to me. I was speculating the same thing, lead oxides. I just don't have enough experience smelting lead to know for sure. There was a lot of surface area on the piece I melted and it was definitely oxidized. The more I think about it, that material floating on the surface of the molten lead reminded me of how the surface of a brownie cake fractures. Kind of like dried out icing. Thanks for your comment.