Smelting metal in your microwave oven

Grab some scrap metal and a microwave oven and you’ll be casting your own metal parts in no time. [Mikeasaurus], who is known for doing strange things like making Silly Putty magnetic or building his own spray paint bottles, doesn’t disappoint this time around. He read about microwave smelting in Popular Science and is giving it a shot himself.

The image above shows him pouring an ingot. He build an insulated brick enclosure inside of the microwave oven, then set it to go ten minutes for a 50/50 lead/tin mixture, or fifteen minutes for silver. This will vary based on the power rating of your microwave. You can see in the video after the break that the setup gave him some trouble shortly after pouring. It wasn’t a problem with the molten metal, but spontaneous combustion of the rigid foam insulation that did him in. We shouldn’t say ‘I told you so’, but that insulation says right on it that it’s flammable!

This isn’t the first time we’ve looked at casting metal melted in a microwave. Check out this other version posted back in 2005.

39 thoughts on “Smelting metal in your microwave oven

      1. I melted lead in a similar amount of time with a fresnel lens on a sunny day (old tire weights), and poured them into a mold… and it would have worked better if I’d considered insulating my crucible… ^..^

      1. I conquer, I also think that hackaday should adopt some kind of “like” system like facebook, or a rating system like engadget, the latter being preferable.

    1. it works by putting in a silicon-carbide block and that absorbs the microwave radiation and gets very hot, so anything that melts at a not too high temperature can be melted.
      Or you can destroy evidence in it I guess, maybe a HD if you are facing an inquiry because you embezzled a 2.6 billion?

    2. Yeah, aluminum’s melting temp is about 1200-something F compared to silver’s 1700-something F. Silver, according to the text, takes 15 minutes of nuking so aluminum should take a little less than that.

  1. Very Very stupid,
    With this amount of lead using a microwave OR a gas hob will contaminate the immediate area with toxic lead.
    So not only will the inside of the microwave be contaminated but also the air, the work surfaces & your cloths.

      1. Agreed. I work with lead daily and nobody has become sick from it at my workplace. Actually unless you’re vaporizing it or grinding/filing it without a mask/respirator you should not have an issue.

  2. So, melting 50/50 solder is a good idea in a microwave? Not really one problem is the resonance of the magnetron tube itself. If the microwave is run without an object to absorb the radiation, a standing wave will form. The energy is likely to burn out the tube. This video should be used in safety training in the “what not to do” section. Water on an appliance? I really doubt that Ag can be melted with 2.4 GHz.

    1. Ken, you’re an idiot who obviously did *not* RTFA.
      It clearly states that he is using Silicon Carbide as a microwave susceptor. I.e. the microwaves are acting on it, i.e. heating it.

      This [heat radiated/convected/conducted] is then used to heat the crucible containing the material being melted.
      In this case the crucible is stainless steel, with a MP [Melting Point] of some 1500oC, way above that of silver [450oC]

  3. Seems just as much as a flop as his refillable “squirt-paint”. It worked, yes, but you could use a stove & pan to do the same thing depending on the alloy. Hell, you could use a fire and bricks to get it done, too.

    Also, smelting would be taking raw ore and getting usable metal out of it. This is melting.

  4. Yes aluminum will melt using this method.

    Concerns about toxic lead are somewhat over blown. Unless you do this day in day out with your nose over the crucible you’re not likely to get any ill effects. Though no lead vapor is better than a miniscule amount.

    As far as frying the magnetron goes, most of the radio waves are absorbed by the SiC refractory placed inside the microwave, but if you’re that concerned a) toss a glass of water in there to catch the extras b)cool the magnetron using a bigger (active)heat sink.

    You definately can melt silver in a microwave, There are a few custom jewelry makers that use ceramic molds to do so. The frequency of operation doesn’t have much to do with the ability to melt a given metal due to the fact that they aren’t heating the metal directly. They all go into the crucible/refractory which in turn heats the metal. The biggest hold up is going to be the microwave wattage and the ability to keep the magnetron inside of it’s safe working temperature. You’re probably not going to be able to melt more than a few ounces of silver but it’ll still melt.

  5. Foam insulation in a melting setup…I’m absolutely shocked it went up in flames…whodathunkit…

    I think most sedate hobbyist would use electric or gas setups for these escapades.

  6. I know of a certain university department who were experimenting with melting tungsten powder using domestic microwaves – worked pretty damn well actually.

  7. Meh, it will microwave… but Will It BLEND?

    Next improvement: an array of magnetrons. I don’t want to wait that long to melt my metals.

  8. I like this guy. makes me feel my projects are way better then i first thought. At least good enough to be posted on HAD.

    At least we get to see his failures. More of a what not to do hacking series. although his silly putty hack was neat.

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