Saturday, December 15, 2012


Today I'm going to talk about thermite.
Possessing thermite is not a crime as long as it's not used or intended to be used in an illegal manner. It's used for cutting metal or welding, so if you do any metal work at all you have a legitimate use for it. I do some lightweight metal working and have used it in the past to cut plate steel - what would take me hours to cut using a cutting wheel (not to mention about a million cutting wheels) can be done in minutes using thermite. It will not make a clean cut (lots of slag) but it beats the hell of changing cutting wheels every 3 minutes. Yes, you can accomplish the same thing by using an arc welder if you have one and cranking up the voltage but sometimes that's not an option.

The military uses thermite to breach metal doors, destroy artillery and mortar tubes and disable vehicles but that's not my purpose here - I'm just trying to educate folks on the fine art of cutting metal. Got it?
Thermite is not an explosive even when contained, it's simply a combination of two common and easily obtained metals that when ignited creates an extremely hot fire that cannot be extinguished by water.

Before I go any further I want to caution you to be extremely careful in all aspects when using thermite. That shit cannot be extinguished, it will burn until the compounds have been exhausted, it showers burning metal once ignited and it's extremely bright and will blind you if you watch it burn. You burn down your fucking garage while cutting metal, it's on you, not me. You have been warned.

There are videos on YouTube showing you how to make it but I'll save you a little time and explain it here, yeah?
Thermite can be made by mixing 8 parts iron oxide (rust) to 3 parts aluminum powder. That's 8 to 3 by weight, not volume. Because aluminum is lighter than the iron oxide it will look like about a 50/50 mix.
If you want moldable thermite (you're cutting something that's upright, like an old safe that you forgot the combination to) mix 4 parts thermite to one part clay. Knead it thoroughly.
Okay, you've got your compounds mixed, you've made your measurements and laid out your mixture in the desired area and it's time to light 'er off. It takes a lot of heat to ignite thermite - your handy Zippo ain't gonna do the trick. Take a sparkler, stick that sucker in there and light it. You can also use a magnesium ribbon to fire it. Magnesium ribbon can be lit with a lighter.

One more time: be extremely careful when using it. It will shower burning metal and it will blind you if you look at it while it's cutting your plate steel. Use welding goggles if you absolutely have to look at it. DO NOT attempt to extinguish it once it starts burning. If you throw any water on it while it's burning, it will cause a steam explosion (the fancy word for that escapes me at the moment) and you'll have hot burning metal everywhere. Trust me on this.

All of the ingredients, including magnesium ribbons, can be obtained from any pyrotechnics website, and aluminum powder can be bought at paint supply stores as it's used for pigment, especially in auto painting. You can make your own rust using steel wool if you so desire but that's more trouble than it's worth.

One more word of caution - do not mix the aluminum powder and iron oxide until you are ready to use it. If you've got a container of it in your shop and it catches fire, you're fucked. If you do have a mixed container and your shop catches fire be sure to tell the responding firemen so they won't spray water on it and cause an explosion injuring or killing themselves.

If you have any further questions about making thermite or how to use it, there are YouTube videos available as well as many articles online such as Wikipedia.

Okay. Again, be safe. Don't use it for anything illegal. Make sure you have plenty of room and no flammables around. Wear goggles. Stay a safe distance away once it starts burning. Have fun.


Anonymous said...

Hydrothermal Explosion. But water versus thermite is more complicated than that. There is so much energy being released by thermite that the water vapor becomes just another source of oxygen to feed the fire.

There is a new rocket fuel that exploits this effect. It is called ALICE or ALuminum ICE rocket.

Water will also result in magnesium fires burning hotter.

Fuzzy in AZ said...

I'm no expert, but I did stay at a Holiday Inn last night: I've used thermite to burn thru tree/thick shrub stumps. Works like a charm. Also, I UNDERSTAND that if you take a 50' coil of fast burning cannon fuse (mostly coiled with a 2-3 foot leader on it) and dump one pound of thermite in the center of it, then light the fuse and run like hell, it'll burn right thru a cop's...I mean a car's...engine block.

wirecutter said...

WHAT??? You mean there's other uses for it besides cutting metal?
Holy shit......

drjim said...

An EXCELLENT source of Iron Oxide is any place that does custom concrete work, as they use it to color the concrete.

And for coming up with that pesky powered Aluminum? Just take some household Aluminum foil (the cheaper the better), and use your BLENDER to turn it into powder.

Just Google for "make aluminum powder with blender" and you'll find dozens of sites and videos.

And I, too, have a genuine, legitimate use for Thermite. Small quantities of it are used to bond ground rods together with heavy cable. It makes a permanent, rust-proof connection that has VERY low Ohmic resistance, exactly what you need for bonding grounds together!

Kerodin said...

I "Think" a regular old kids sparkler has enough magnesium burning to ignite your thermite.

Never tried it myself, of course.


drjim said...

I seem to recall reading about being able to light it with a road flare, but you have to be careful, as you're pretty close to it.

The "thermite" device we use to weld ground rods with (called Cadweld) has a little initiator in it.

Neat stuff!

Glenn B said...

I am willing to bet that at least a few people who read this are going to have some fun with this stuff.

Wrench said...

Can iron cuttings from brake rotor/drum lathe be used or are they to large?

RegT said...

A good source for kits or components:

The magnesium ribbon is cheap, and the shipping is free on the ribbon (if ordered separately).

dhanna59 said...

Holy Crap Guys, if you want to take out a c** car, just put a 12 gauge slug thru the oil cooler and radiator into the block...If you play with fire and "splody" stuff, you just might become a statistic, just sayin.

wirecutter said...

Okay, the purpose of this post was to teach folks how to cut metal, not disable vehicles.
Destroying shit with thermite requires that you get up close and personal, something that's to be avoided at all costs.
The ONLY reason I mentioned the military uses is because that's what comes to mind when people hear the word thermite.

dhanna59 said...

P. S. No Nimrod drjim,you cannot turn aluminum foil into powder in afrikkin do I know? I just tried it...Nimrod.

wirecutter said...

Gonna ask for a new blender for Christmas, D?