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

[rnorman3]

would a rock tumbler work as well?

[pwnag3]

Yes

[Johnhall44]

I think I have an experiment to do using arrows =D

[reedz]

It would be awesome if you could freeze an ignitor into it, like a press button that when you throw it...it burns.

[Peter5465]

Can someone help me out here?

http://www.instructables.com/answers/How-to-i-turn-a-computer-power-supply-into-a-iron-/

[dlmetcalf]

Thanks for the Instructable. I'm going to second another commenter and recommend 2% Dextrin as the binder instead of plaster (bake cornstarch a.k.a. cornflour in the oven for 2 hours at 200C, mixing every 30 mins). Lighting it with KMnO4 and glycerol is generally much safer than a propane torch or flash powder mix too (at least gives some delay). As a word of caution, making thermite is probably classed an manufacturing pyrotechnics and illegal in most places. Unless you have experience with pyrotechnics, safety practices, solid chemistry knowledge, etc. don't mess with it. Also if you add chlorate (as one poster suggested), make sure you don't use First Fire Mix as it contains sulfur which can degrade to trace amounts of sulfuric acid and cause spontaneous combustion.

[afartinthewind]

Forgot to add that when the block is x'ed out with 1/4" deep grooves just sand it flush and go again. Also check your alloy, just because it's Al doesn't mean it's pure.

[afartinthewind]

I like to place my iron oxide in a small coffee can with some old BB's and ball bearings and give it a good shake for a few minutes. As for the aluminum I have a 6x6 block from a local hardware store that I cut grooves into with a hacksaw. Light pressure will get close to a fine powder.

[SirStokes]

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

[ilpug]

The part that also says that that isn't something that should be involved with this site.

[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?

[ilpug]

built in fuse: I like it!

[Everett_McKinley]

The best way I found to do this is using a metal pipe about 4 or 5 in. wide and how ever long you want I'd keep it around 3 feet long. Stuffing the pipe with steel wool, lighting it (duh), and having a fan blow through the pipe from one end. it works great. ;)

[mrmerino]

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

[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

[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.