Cast Thermite

There are plenty of Instructables and other how-to's on making Thermite, the incendiary mixture that can not only raise, but also burn, eyebrows. (The concept for this Instructable came from 'the Anarchists Cookbook', and since it doesn't give many details...here's how I do it.) Now, there's nothing wrong with powdered forms of Thermite, that's how I got started a few years back, but sometimes you just want something rock solid that burns nice and bright/hot.

That's where Cast Thermite comes in. And the best part is, If you have some thermite on hand already, it's pretty easy to make! If you don't, never fear, for I will be starting at the beginning with nothing but the raw materials.

Step 1 Obtain the Materials

So you made it through the intro? Good. There's something that must be said before we go any further. I'm not liable. For anything. Do your homework and be sure you know what safety precautions to take when handling something like thermite, such as not looking at it during ignition since it gives off harmful ultraviolet light! Be smart, treat this stuff with the respect it deserves. It's not flash powder but it's certainly not sugar either. ;-)

Now that that's out of the way, onto the fun part. The preparations!

The first thing to do is understand what thermite is made up of. Most commonly, homemade thermite is made up of iron oxide (rust) and granule or powered aluminum. When mixed together, these two metals create an incendiary capable of reaching temperatures of several thousand degrees. For more info check thermite's Wiki page. So:

What we need:

• Fine (0000) Steel Wool (not pictured)
• Aluminum
• Some kind of scale
• Plaster of Paris
• Handling materials (spoon, cup, paper, coffee can...)
• Some kind of mold to cast your thermite in

While I'm at it, I'll explain the best way to get a hold of the materials.

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• Steel Wool

Off to the hardware store! Honestly though, I buy my steel wool at Walmart unless I can find bulk fine grade steel wool at our nearby Harbor Freight .

• Aluminum

Well, you could always go online and purchase some high grade Aluminum powder like I did. Before I thought to do that, I just ground strips of aluminum foil in a cheap coffee grinder. IMHO, the larger grains made from the coffee grinder method make for brighter and more enjoyable light shows.

• Scale/Plaster of Paris

Ever heard of Michaels? It's a nice little place a lot like Hobby Lobby. Plaster of Paris and the scale can be bought at either of these places, and probably at Walmart as well.

• The Mold

Use anything you want to, whatever suits your fancy. I use a small ice cube tray. Film canisters would probably work fairly well, as would larger tupperware containers for really big batches. Whatever floats your boat.

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Finally, you say. I've got everything you told me to get. Let's get started!

Comments

[mrmerino]

You can also light the steel wool with a 9V battery.

[electroboy1337]

Would it be possible to simply just stick a 10 cm or so length of magnesium ribbon in each cube while they're setting?

[mayan guitarist]

i need to grind up aluminum is there another way besides a coffee grinder

[StickStoneBone]

Small rock tumbler with BB's works great for pieces of Aluminum Foil.

[the_doctor]

aluminum seems to be a problem for a lot of people i have found that the best quality of aluminum powder can be found inside of an Etch-a-Sketch. the grey powder in side of it is as fine a powder as it comes you can even use the beads to give a good combination of coolness and functionality!

[StickStoneBone]

...again, a rock tumbler with BB and pieces of Aluminum Foil WORKS AWESOME. In my opinion buying or even salvaging an etch-a-sketch for the aluminum powder is:

a) More work than it's worth.
b) Waste of an etch-a-sketch (they're not hard to fix)

[pindalanderz]

I just took a file and scraped some pop tabs across it.

[cody777]

i took a dremel to a can and collected the shavings in a cup ps nice icon

[ramkanwar55]

you could just use the stone age method of using a file on an iron screw/nail

[SirStokes]

Where in the anarchist's cookbook does it talk about thermite?

[The Ideanator]

Could you post pics/video of it being used and the kind of damage it can do?

[bio-logical]

when i try to refine mine i use a sifter and the iron oxide doesn't seem to be anywhere but the outside of the strand because i keep seeing silver. any help

[codongolev]

you could probably use finer steel wool, and maybe try burning it with a hacked lighter to keep the reaction going.

[ilpug]

This is very awesome. I have made thermite many times before, but i have never thought of molding it. It is a cool idea, but seems a bit useless in my opinion. It seems like thermite would burn better if it was in a loose powder form, not a solid block. I have used the exact same method you show here to make it, and it works great, for those who doubt it. Here is how i ignite my thermite. I take a road flare, and cut it open. then i make a little divot on top of the thermite and fill it half way with road flare powder. then i take a ball of steel wool (the very rough kind) and stick it in the powder. then i cover it up, leaving only two little bits of the steel wool sticking out. I connect alligator clips to each of these sticking out parts. Then i wire it all up to a car battery very far away, flip the switch, and watch the fireworks. Through very dark glasses, of course.

[Joelsefur]

You have no idea what your doing. Ground aluminum foil, burnt steel wool, and a propane torch does not make thermite. Those materials would never combust in such a raw form and from such a small amount of heat. Even if you got this to ignite it wouldn't be much more than a little light and fire. It wouldn't even compare to actual thermite.

[Zlwilly]

Really? Hmm. That's strange, have you actually followed the instructions and tried it. It works perfectly for me. Bright, hot, and altogether thermite-y in nature.

All due respect, from personal experience doing this countless times, the materials definitely do combust ferociously. Simply put, you're incorrect. But don't take my word for it. Try it for yourself. :)

[Jimmy Proton]

shouldn't the iron oxide be reddish brown?

[WhiteCheddar360]

http://www.youtube.com/watch?v=9aQ1p9-EPpI

[pyrobrain394]

hay man i had a cool idea!!! After pouring the thermite you could stick a magnesium strip down into it and voila, fuse and charge all in 1

[tulekah]

hey! let's you and him play with thermite! i'll just kick back (way back) and watch natural selection in action!

[Victor Lam]

is it possible to use the pre-ground aluminum oxide used for sand blasting?

[needs_more_to_do]

No it is not possible. Aluminum oxide is not aluminum. To answer your question more thoroughly remember that thermite releases heat by striping the oxygen off of the iron and 'burning' the aluminum. If your aluminum is pre-oxidized this reaction cannot occur.

[Nicola Tesla]

how could u do this with play doh or clay?

[fragmaster4]

Thermite must be lit with something like a Magnesium fuse, or so I heard. I think a blow torch would work too.

[micromuffin]

a blowtorch would work but if you tried to use it your hand would burn off.

[Broom]

Sparklers should start it.

[mattbomb]

would mare-balls(the glass ones) would they work or just break

[mattbomb]

and another thing is thermite is self oxidizing. so theres no putting it out. PEROID

[djamp1983]

another way to get aluminum is find an old etch-a-sketch at a garage sale. the gray powder in it is pure aluminum and it's sealed off to prevent oxidation, which will slow down your reaction a lot if it even let's it start at all.

[lifeforce4]

I thought Aluminum was not magnetic. Doesn't etch a sketch work by magnet power?

[jeff-o]

You're thinking of a magnadoodle. The etch-a-sketch is different.

[djamp1983]

not really, the powderized aluminum stcks to the inside of the glass. much like if you pull one apart you'll find it will stick to just about everything. the mechanism inside that makes the lines just pushes it aside to leave exposed glass.

[DavidRobertson]

i think you mean magnetism

[davenator]

I just disassembled my etch a sketch. They are really hard to take apart, but the powder inside is extremely fine grain, and if you touch it your skin will look metallic. It is also hard to clean up.

[djamp1983]

yes, they are quite the pain in the butt to take apart. i've also found this is only cost effective if you can get one for either really cheap or free. otherwise, you're better off trying to get the aluminum fro a hobby shop.

[wizodd]

This is NOT a good idea! It will work well with fairly course aluminum, but aluminum powder gets touchier and touchier around water as it gets finer. A mix of very fine (100mesh&finer) can ignite by getting damp. This risk is higher with ultra fine (black) aluminum, and the addition of magnesium will increase the likelyhood. The resulting cubes will burn a little cooler because they will use up some energy to turn the plaster back into powdered (anhydrous) form--though probably not noticeably so. The addition of sulfur to make thermate, also lowers the ignition temperature to well below the melting point of aluminum. It is not a good idea, for the same reason, to keep mixed thermite powder on hand--moisture can set it off spontaneously (it is also illegal in many places.) Always store fuels (like aluminum) away from oxidizers (iron oxide) in cool dry places. There are a number of different formulations for termite and related incendiaries. Some are designed to cut, some to weld, some to set fires. It won't normally explode, but if you contaminate the mix with other things, anything can happen. A little bit of a stronger oxidizer might cause part of the batch to explode--sending molten iron spraying in all directions. Such a device could be made by surrounding a small HE charge, or even a glass vial of water.... One thing that the mixes can do is put out a LOT of heat in a very small space in a very short time. In or under water this makes a spectacular (albeit dangerous) show. Most such experimentation should be done at a good distance. Be careful about setting it off on the ground too...if you have a porous rock and it hits the molten iron, it may explode if it has any water soaked into it.

[hogey74]

Yeah be careful with this stuff - molten iron goes straight through clothes and human tissue and its only half the temp of Thermite! I'm as in favor of burning and blowing up stuff as the next man but the quick refresher I just gave myself via google reminded me how careful you have to be with thermite. You could probably burn a hole to the center of the earth with it. Which would be pretty cool actually ...

[Broom]

Well said. Thanks for putting some hard facts into this discussion. Thermite can be fun, but VERY VERY dangerous. Loose blackpowder, burning weeds off in your back yard, lighting spray powders - hee hee, silly stuff. But thermite can do tremendous damage, even in small amounts. Play carefully!

[Nowandthen]

Are those Incendiary Termites like "Fire Ants"?

[hogey74]

he hehe - thats a terrible "dad" joke!