Tonight I tried brass in the microwave crucible project. As with previous attempts using the propane foundry, it blew out a ton of zinc oxide, but less so, maybe because the top insulation prevents as much oxygen getting in. I can't find my big industrial copper waste so I'm melting brass cartridges. I collect lead off the road while biking and trade it with my work buddy for timed out reloads.

When I lift the top insulation off the whole crucible flares up with a yellow flame. That's the zinc burning.

Here's a little brass ingot, not much to show, but still ok given the circumstances. 14 minutes in the microwave.