Is it safe to use a microwave for small aluminum melts?

Seeing as how I have a spare microwave, and I've heard of people doing melts in a household microwave, I though that I'd try it myself.

What do I need to add so that I don't destroy the microwave?

"From a hardware store on Fourth Street, I bought a silicon carbide sharpening stone and 3 pounds of tin/silver plumber's solder; from Macy's, I purchased a microwave-safe casserole dish and a stainless-steel measuring cup; and at Williams-Sonoma, I found a cute cast-iron cornbread fish mold and a pair of long-cuff leather grilling gloves. " - PopSci's Theo Gray

A good source of silicon carbide? A better material? (I don't even understand its purpose here).

jtobako10 years ago
Silicon Carbide will absorb microwaves and get hot-hot enough to melt some metals. It is used in SOME sharpening stones and in SOME crucibles (containers for melting metals). A jewelery supply, Budget Casting (home foundry supplier) or (occasionally) Harbor Freight (local cheep tool store) carry the crucibles, a hardware store would have the sharpening store (but make sure it says 'Silicon Carbide').

A combo of carbon/graphite and magnetite/rust will do the same. Read David Reid for more info.
carbon (author)  jtobako10 years ago
So, basically, we have a cup of metal sitting on the sharpening stone, and that in turn sitting on something insulating but microwave-invisible? For the cup: Would it be alright to just use one made of stainless steel? For the insulator: Firebrick? Fiberglass insulation? Ceramic wool? Would any of these work?
jtobako carbon10 years ago
The crucible works better because the heat is in better contact with the metal, but yes. Stainless works as a crucible, but keep an eye on it just to make sure. And make sure that there aren't any sharp edges for arcing to form on : ) Insulating firebrick (the lightweight stuff, you can scratch/cut it easily) or ceramic wool work, fiberglass might start melting-not sure of the heat resistance and temp that the silicon carbide is going to get to.