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.

  • 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.

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

Apparently sparklers work extremely well to ignite the thermite
<p>I already have a reel of magnesium ribbon for this purpose. So I'm assuming if I let a piece of it dry with the mold so that it sticks out like a fuse it will work. </p>
Will the putty stick to surfaces?
Easiest place to get both iron oxide and aluminum powder is a website called United Nuclear,
Could you use the powdered thermite(which is easier to ignite) to ignite the solid thermite.you could even make some sort of thermite based fuse,where you tightly wrap thermite in a paper tube,then put a magnesium ribbon or powder in the end to start the reaction
<p>Hi guys i have a question about this iron oxide i understand its rust but all the videos i've watched about making iron oxide its a liquid with a battry charger and old nail etc. Im sure youve seen them but if i were to scrape rust off let's say an old bike then used a ball mill,mortar pestal,etc would that still be iron oxide or something else? thanks</p>
<p>It would be, but most likely it's hydrated iron oxide (i.e a molecule of iron oxide that has water chemically bonded to it). To avoid the danger of steam explosion the water should be driven out of it by drying it in an oven or something.</p>
<p>How did you grind the aluminum, or can you use aluminum oxide like the kind used for polishing stone?</p>
Very thorough explanation. I'm curious to see with what type of ignition sources you come up with.
i forget the name of it but there's a type of radiator repair stuff that contains powdered aluminum and you can also obtain it from an etch-a-sketch
<p>You got that from breaking bad. lol.</p>
<p>The radiator repair stuff is called &quot;Stop Leak&quot;'</p>
make a castle out of molded tupperware brics, pt army men on it, and light it on fire
That- Is- Brilliant. I always thought it would be a great idea to make thermite legos. Think about the possibilities!
news media: BREAKING NEWS!<br>-Man makes Legos fun for grown men....<br>-New fire hazards in toy stores.
<p>this is cool. I have never made thermite before but I want to try this. </p>
Would it be possible to simply just stick a 10 cm or so length of magnesium ribbon in each cube while they're setting?
thats what I have always done when I have ever used thermite
built in fuse: I like it!
<p>How did this appear in my email feed? I know I'm a fan of thermite, but this is 6-ish years old... and doesn't appear that active currently. So, why feature it in an email blast? </p><p>Unless doing thermite demos is a good halloween treat (umm, really? really?) then this seems a bit inappropriate to me.</p>
I wonder if a mixture of potassium permanganate and glycerine would ignite it, if you could figure out how to mix them from a distance on the thermite that is. <br>
<p>That's how I light my thermite. The reaction is delayed by several seconds, so you have time to move to safety.</p>
<p>Use old prescription, film canisters filled 2/3 then you could thread fuse thru the cap and into the mix before dry... Just a thought.</p>
<p>Hi Zlwilly &amp; The Instructables Community,</p><p>Just a thought on possibly problamatic ignition.</p><p>I have heard of people using sparklers to ignite the powdered mixture, but obviously this cannot work here. </p><p>So I got thinking, why be constrained by this?</p><p>I thought that while the mixture is setting why no put a short cut length of drinking straw into the top of the mixture (possibly plugged to stop water equalisation). Once set you then have a convienent hole to place either a short length or a full sparkler for a timed fuse.</p><p>Just a thought as I said, but I would love to hear if someone gave it a go!</p><p>Regards, </p><p>The Apple Sauce Man</p>
is it possible to use the pre-ground aluminum oxide used for sand blasting?
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.
Aluminum metal (Even in alloy) forms an oxide layer almost instantly after having the existing oxide layer removed and then being exposed to oxygen. I don't remember the exact time, but its on the order of nanoseconds.
shouldn't the iron oxide be reddish brown?
Fe(III) Oxide is usually a brighter &quot;brick&quot; red
Hey not sure if anyone else has mentioned this but you'll have an easier time mixing if you add the powder to the water. It will also give you a few extra minutes of play time before it starts to set. Once it's mixed add a pinch of table salt and it will halve the setting time. This only works with plaster of Paris, with harder plasters like dental ones it slows the reaction. Don't ask me why I don't know. Not sure if the salt would affect the burn though.
would a rock tumbler work as well?
I think I have an experiment to do using arrows =D
a better way to get iron oxide is by the electrolosis of a salt water solution with some iron rods. Not graphite. Then filter the muck and let it dry. Grind it up in a pestle and mortar and there powdered iron oxide.
That is a 'better' way to get iron oxide, if you're looking for efficiency from cost/time/end-product mass Vs. beginning mass. There is one thing that you did not consider, though, and that is the fact that when you make iron oxide via electrolysis you do not have an end product of Fe2O3 which is the best iron oxide to use for thermite mixtures.
Whats wrong with Fe3O4? it has more oxygen, shouldn't that let the thermite burn better?
I dont believe you can make Fe3O4
i&nbsp; didnt think that you could make h2o2 but i was worng...
Can someone help me out here? <br> <br>https://www.instructables.com/answers/How-to-i-turn-a-computer-power-supply-into-a-iron-/ <br> <br>
I did through <a rel="nofollow" href="http://antique-engines.com/electrol-details.asp">water electrolysis</a>. When you get to the drying part, evaporate it as heating it(in a propane grill) turns most of it back into Fe2O3.<br/><br/>(pic: red is the grilled, black is evaporated)<br/>
oh kk nvm<br />
nice icon
It would be awesome if you could freeze an ignitor into it, like a press button that when you throw it...it burns.
Can someone help me out here? <br> <br>https://www.instructables.com/answers/How-to-i-turn-a-computer-power-supply-into-a-iron-/ <br> <br>
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.
Forgot to add that when the block is x'ed out with 1/4&quot; deep grooves just sand it flush and go again. Also check your alloy, just because it's Al doesn't mean it's pure.
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.
Where in the anarchist's cookbook does it talk about thermite?
The part that also says that that isn't something that should be involved with this site.
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. ;)

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Bio: What's to say? I have a deep passion for all things electrical and mechanical, and the more of it I can get my hands ... More »
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