.... Thermite Incendiaries and Formulas ....

DISCLAIMER : The making and possesion of the following devices and mixtures is probably illegal in most communities. The incendiaries are capable of burning in excess of 5400 degrees F. and are next to impossible to extinguish. If you make them you accept all responsibility for their possesion and use. You also accept all responsibility for your own stupidity and carelessness. This information is intended solely to educate.

All Formulas are by Weight

Thermites are a group of pyrotechnics mixtures in which a reactive metal reduces oxygen from a metallic oxide. This produces a lot of heat, slag and pure metal. The most common themite is ferroaluminum thermite, made from aluminum (reactive metal) and iron oxide (metal oxide). When it burns it produces aluminum oxide (slag) and pure iron.

Thermite is usually used to cut or weld metal. As an experiment, a 3lb. brick of thermite was placed on an aluminum engine block. After the thermite was done burning, only a small portion of block was melted. However, the block was very warped out of shape plus there were cracks all through the block. Ferro-thermite produces about 930 calories per gram

The usual proportions of ferro-thermite are 25% aluminum and 75% iron oxide The iron oxide usually used is not rust (Fe2O3) but iron scale (Fe3O4).Rust will work but you may want to adjust the mixture to about 77% rust. The aluminum is usually coarse powder to help slow down the burning rate. The chemicals are mixed together thoroughly and compressed into a suitable container. A first fire mix is poured on top and ignited.

NOTE: Thermites are generally very safe to mix and store. They are not shock or friction sensitive and ignite at about 2000 degrees F.

A first fire mix is a mixture that ignites easier than thermite and burns hot enough to light the thermite reliably. A very good one is :

Mix the above thoroughly and combine 2 parts of it with 1 part of finely powdered ferro-thermite. The resulting mixture can be light by safety fuse and burns intensely.

One problem with thermites is the difference in weight between the aluminum and the oxide. This causes them to separate out rendering the thermite useless. One way to fix this is to use a binder to hold the chemicals to each other. Sulfur is good for this. Called Diasite, this formula uses sulfur to bind all the chemicals together. It's drawback is the thermite must be heated to melt the sulfur.

Mix the oxide and aluminum together and put them in an oven at 325 degrees F. and let the mix heat for a while. When the mixture is hot sprinkle the sulfur over it and mix well. Put this back in the oven for a few minutes to melt all the sulfur. Pull it back out and mix it again. While it is still hot, load into containers for use. When it cools, drill out the diasite to hold about 10 - 15 grams of first fire mix.

When diasite burns it forms sulfide compounds that release hydrogen sulfide when in contact with water. This rotten egg odor can hamper fire fighting efforts.

Thermite can be made not to separate by compressing it under a couple of tons pressure. The resulting pellet is strong and burns slower than thermite powder.

CAST THERMITE: This formula can be cast into molds or containers and hardens into a solid mass. It does not produce as much iron as regular ferro-thermite , but it makes a slag which stays liquid a lot longer. Make a mixtures as follows.

Mix together well and and enough water to wet down plaster. Pour it into a mold and let it sit for 1/2 hour. Pour off any extra water that seperates out on top. Let this dry in the sun for at least a week. Or dry in the sun for one day and put in a 250 degree F. oven for a couple of hours. Drill it out for a first fire mix when dry.


Thermite can be made to explode by taking the cast thermite formula and substituting fine powdered aluminum for the coarse/fine mix. Take 15 grams of first fire mix and put in the center of a piece of aluminum foil. Insert a waterproof fuse into the mix and gather up the foil around the fuse. Waterproof the foil/fuse with a thin coat of wax. Obtain a two- piece spherical mold with a diameter of about 4-5 inches. Wax or oil the inside of the mold to help release the thermite. Now, fill one half of the mold with the cast thermite. Put the first fire/fuse package into the center of the filled mold. Fill the other half of the mold with the thermite and assemble mold. The mold will have to have a hole in it for the fuse to stick out. In about an hour, carefully separate the mold. You should have a ball of thermite with the first fire mix in the center of it, and the fuse sticking out of the ball. Dry the ball in the sun for about a week.


The fuse ignites the first fire mix which in turn ignites the thermite. Since the thermite is ignited from the center out, the heat builds up in the thermite and it burns faster than normal. The result is a small explosion. The thermite ball burns in a split second and throws molten iron and slag around. Use this carefully !


To cut metal with thermite, take a refractory crucible and drill a 1/4 in. hole in the bottom. Epoxy a thin (20 ga.) sheet of mild steel over the hole. Allow the epoxy to dry. Fill the crucible with ferro-thermite and insert a first fire igniter in the thermite. Fashion a standoff to the crucible. This should hold the crucible about 1 1/2 in. up. Place the well over your target and ignite the first fire. The well works this way. The thermite burns, making slag and iron. Since the iron is heavier it goes to the bottom of the well. The molten iron burns through the metal sheet. This produces a small delay which gives the iron and slag more time to separate fully. The molten iron drips out through the hole in the bottom of the crucible. The standoff allows the thermite to continue flowing out of the crucible. The force of the dripping iron bores a hole in the target.

A 2 lb. thermite well can penetrate up to 3/4 in. of steel. Experiment with different configurations to get maximum penetration. For a crucible, try a flower pot coated with a magnesium oxide layer. Sometimes the pot cracks however. Take the cast thermite formula and add 50% ferro-thermite to it. This produces a fair amount of iron plus a very liquid slag.


This is a very dangerous device. Ask yourself if you really truly want to make it before you do any work on it. It is next to impossible to give any dimensions of containers or weights of charges because of the availability of parts changes from one person to the next. However here is a general description of this device affectionately known as a HELLHOUND.

Make a thermite charge in a 1/8 in. wall pipe. This charge must be electrically ignited. At the opposite end of the pipe away from the ignitor side put a small explosive charge of flash powder weighing about 1 oz. Drill a small hole in a pipe end cap and run the wires from the ignitor through the hole. Seal the wires and hole up with fuel proof epoxy or cement. Try ferrule cement available at sporting goods stores. Dope the threads of the end caps with a good pipe dope and screw them onto the pipe. This gives you a thermite charge in an iron pipe arranged so that when the thermite is electrically ignited, it will burn from one end to the other finally setting of the flash powder charge.

Place this device in a larger pipe or very stout metal container which is sealed at one end. Use a couple of metal "spiders" to keep the device away from the walls or ends of the larger container. Run the wires out through the wall of the container and seal the wires with the fuel proof epoxy. Fill the container with a volatile liquid fuel. Acetone or gasoline works great. Now seal up the container with an appropriate end cap and it is done.

The device works like this: Attach a timer-power supply to the wires. When the thermite is ignited it superheats the liquid fuel. Since the container is strong enough to hold the pressure the fuel does not boil. When the thermite burns down to the explosive, it explodes rupturing the container and releasing the superheated fuel. The fuel expands, cooling off and making a fine mist and vapor that mixes with the surrounding air. The hot thermite slag is also thrown into the air which ignites the fuel-air mix. The result is obvious. Try about 1 1/2 lbs of thermite to a gallon of fuel. For the pressure vessel, try an old pressure cooker. Because the fuel may dissolve the epoxy don't keep this device around for very long. But ask yourself, do you really want to make this?


Thermites can also be made from teflon-magnesium or metal flourides-magnesium or aluminum. If there is an excess of flouride compound in the mixture, flourine gas can be released. Flourine is extremely corrosive and reactive. The gas can cause organic material to burst into flames by mere contact. For teflon-magnesium use 67% teflon and 33% magnesium A strong first fire igniter should be used to ignite this mixture. Both the teflon and the magnesium should be in powdered form. Do not inhale any smoke from the burning mixture.

If you use metal-florides instead of teflon, use flourides of low energy metals. Lead flouride is a good example. Try using 90% lead flouride and 10% aluminum.

Warning: Flouride compounds can be very poisonous. They are approximately equal to cyanide compounds.

Another exotic mix is tricalcium orthophosphate and aluminum. When this burns,it forms calcium phosphide which when contacts water releases hydrogen phosphide which can ignite spontaneously in air.

Tricalcium orthophosphate has the formula Ca3(PO4)2 and is known as white- lockite. Use about 75% orthophosphate and 25% aluminum. This ratio may have to be altered for better burning as I have not experimented with it much and don't know if more aluminum may reduce the calcium better. It does work but it is a hard to ignite mixture. A first fire mix containing a few percent of magnesium works well.

Fighting thermite fires:

Two ways to fight thermite fires are either smothering the thermite with sand. This doesn't put out the thermite but it does help contain it and block some of the heat.

The other way is to flood the thermite with a great amount of water. This helps to break the thermite apart and stop the reaction. If you use a small amount of water, an explosion may result as the thermite may reduce the water and release hydrogen gas.

Thermite can start fires from the heat radiating from the reaction. Nearby flammable substances can catch fire even though no sparks or flame touch them.

*** Kilroy was here ***

Compiled for the '94 CookBook 4.14 -- Exodus