How-to: Thermite hard drive destruction



A couple different methods of containing the thermite above the hard drive were tried and we quickly found the best way is a clay flower pot with the drip tray for a lid. An Altoids tin was also tried, but it burned up to quickly. Molding a cement container was also attempted. Since thermite is extremely hard to ignite, sparklers that were left over from the 4th of July were used, and offered a very reliable method of ignition.

Our goal was to completely destroy the drive while it was still in the computer case. The theoretical application is to destroy the disk at a moments notice so it won’t fall into the wrong hands. After testing multiple methods, placing about 1 pound of thermite in a clay flower pot and lighting from the drain hole in the bottom yielded the best results. This could easily be placed in the 5.25″ bays above the drive.

A thermite reaction is a process in which the correct mixture of metallic fuels are combined with a metal oxidizer and ignited. Ignition itself requires extremely high temperatures, but once ignited, thermite supplies its own source of oxygen. It can potentially burn underwater when mixed properly. Thermite is usually used to weld railroad ties together.

The most common thermite is “black or blue iron oxide (Fe3O4), produced by oxidizing iron in an oxygen-rich environment under high heat” and Aluminum(Al). Red iron(III) oxide (Fe2O3), commonly known as rust, can also be used. There are many chemicals that can make thermite; the mixtures used to make thermite therefore vary, causing confusing and changing mixture ratios.

Since the oxidation of one substance involves the reduction of another, this type of reaction is often called redox reaction. In the following balanced reaction, 8Al + 3fe3O4 = 4Al2O3 + 9Fe + Heat. The element Al is oxidized, but Fe is reduced. This reaction is also called a displacement reaction because Al displaces Fe in the oxide. Because of the nature of this reaction, the correct ratio of substances is important to ensure the optimum amounts of fuel (aluminum) and oxygen (iron oxide) within the mixture. Thermite is very safe to handle because of the high ignition temperatures required, sparklers were used in this instance, however magnesium ribbon can also be used. We think an electric pyrogen igniter would be a far better choice for ignition, instead of unreliable methods.

There are two important aspects to ensure a successful reaction. Thorough/even mixing and smallest possible powder particle size. If thermite is not adequately mixed, it may be difficult to ignite or maintain the reaction. One problem when mixing thermite is the difference in weight between the aluminum and the iron oxide. This causes them to separate out rendering the thermite useless. The process used here with great success was five minutes in a rock tumbler. Powder particle size is measured with a measurement called mesh. Passing the powder through a mesh will determine the largest particle size, this reaction performs best with the smallest obtainable mesh size. The mesh size for aluminum was 1200 mesh and black iron oxide was 300 mesh.

The total enthalpy or heat content released is -3.677 kJoule per gram of Fe3O4/AL thermite. The ratio of Fe3O4 to aluminum powder by weight is about 3.22 to 1, according to the reaction’s stoichiometry. The reaction photographed was 200 grams of Aluminum and 644 grams of black iron oxide yielding 2368 kJoules of heat. This was more than was required to adequately destroy the hard drive, a smaller amount could have been used, and still destroyed the platters. It would have even been better controlled, or better yet contained within the computer case. What fun is that?

Using thermite to destroy a hard drive is a very violent and destructive process. Great care should be taken as the molten metal can splash and sputter for a long distance.

The reaction begins to sputter.

The thermite has just contacted the hard drive.

Things are really hot now!

Most of the reaction is completed.

The molten thermite, platters and most of the aluminum frame from the hard drive in the bottom of the case.

Above are the molten hard drive platters destroyed with 844 grams of thermite. It takes about this much thermite contained directly above the drive to get the job done, if it is not you will just get a superficial fire.

Over all the destruction of the drive and platters was accomplished in all cases in a matter of seconds. This is by far a guaranteed method of destroying data in a time of need. We’re pretty sure this will prevent most forensic data recovery methods.

Below is a video of Brainiac using thermite to burn cars and trying to stop the reaction with liquid nitrogen.

Here’s the directors cut of the thermite video which contains 4 extra minutes:

Finally, please do not try this.


  1. Aaron says:


  2. ghos7man says:

    great video and indepth research
    One of your best articles yet

  3. cde says:

    Doing this when there is a warrant for the drive will result in a judge being forced to assume the drive had the evidence about the crime you will be charged with. As such, it is worse then having possible circumstantial evidence.

    • NotYetALawyer says:

      You are clearly not a lawyer–the fact that you didn’t explain that your statement is only applicable to civil court is a giveaway. When stating a legal opinion it is probably fair to tell your audience that you aren’t a lawyer. For the record, I am not.

      The absence of evidence is not evidence. In other words, neither the judge nor the jury will be able to draw any inferences regarding what may have been on the hard drive in CRIMINAL court.

      What will happen is that you will be charged with Tampering with Evidence. That would require that they prove you knew there was a search warrant.

      In CIVIL court an inference may be drawn and you may lose the case. Again, the opposing party will have to show that you deliberately destroyed evidence. My company specifies that data will be retained for 3 years or the amount of time required by law (whichever is longer) and then the drive will be destroyed. As long as data retention is maintained to the extent required by law and the destruction was customary, you’re unlikely to be hit with any default judgment or other penalty for thermiting that mofo.

      • NotYetALawyer says:

        Uggh. I got it wrong to: you said warrant. That means criminal only, so no inference. But the jury will be instructed that you destroyed the drive.

        And, to the point: thermite rocks and it is a great way to make sure you AREN’T sued for accidentally releasing data.

  4. Wait… I’m not satisfied the convection eddies of the molten platters is sufficiently random to be secure.

    I demand another writeup involving ammonium nitrate.

  5. MRE says:

    @cde: yeah, not to mention the subsequent arson charges, destruction of property (if you live in an apartment), insurance hassles, etc that arise from burning down the house!

    Has anyone done an in depth recoverability analysis on a hard drive put in the microwave? Its far less like lighting the monk on fire in protest.

  6. MRE says:

    and by the way.. this just feels really “anarchists cookbook” to me.
    I dunno… maby it feels a little much, because I dont walk around with aluminum foil on my head.

  7. Fred says:

    In the main article text, it states “Thermite is usually
    used to weld railroad ties together.” The parts being welded
    in the video are rails; ties are the wooden, steel or
    concrete supports that rest on a bed of stone and support
    the rails.

  8. Paul Klemstine says:

    Mix the Thermite with an oxidizer such as Potassium
    Chlorate, and the entire reaction will happen
    instantaneously. I just about blew my hand off lighting
    this with a match. Order everything you need here:

  9. Randy says:

    “Finally, please do not try this.”

    Too late already did it!
    I love this stuff!

  10. Rehab2021 says:

    Just surround your system with firebrick or a concrete enclosure
    and you’re all set. Great article.

  11. stunmonkey says:

    If you put the sensitive drives in a heavy safe, along
    with any other documents you may require destroyed, you
    have no worries of danger or mess.
    Steel safes do contain it. I know, as there is already
    one company who makes such safes already. Embassies really
    tend to like ‘em.

  12. threepointone says:

    what company makes these safes, and exactly how are they constructed? Unless i’m mistaken, thermite melts iron, so maybe they have some high temperature layer in it somewhere?

    I think there might be a way to stop the thermite–liquid nitrogen is actually a horrible candidate; although it [i]is[/i] really cold, it has very little heat capacity (which is probably more important in this case–you have to “sap” the energy from the reaction to prevent it from being able to sustain itself). A huge block of ice might actually do the trick (too lazy to do the calculations at the moment)

  13. bad1deas says:

    Thermite is illegal to make. Doing so in a post 9/11 world
    is a very bad idea.

    The fbi have electron scanning microscopes and could gain
    back data from almost any level of destruction; termite is
    the one exception if the disc were to be completely
    incinerated then no level of data could be recovered.

    If the fbi are after you and you have prior knowledge
    better to format the laptop take your laptop to a
    public place make sure you are not followed. Place laptop
    down for ten minutes. Wait till it is stolen.

    OR format the drive … just toss it out … preferably
    somewhere where it wont be found. smash it up flush it
    piece by piece down a walmart toilet.
    anyone asks it died and you threw it away.
    nothing illegal about that…

  14. rageahol says:

    have you tried igliting it with a model rocket starter? that would give you a nice option for computer control of the wanton destruction.

  15. WestfW says:

    I have to disagree with the “finest powders possible” recomendation. I howned some commercial thermite once; it has quite coarse particles.
    Yes, this makes it significantly harder to ignite, but it also rsults in a somewhat slower and more controlled burn, yielding a nice directable stream of molten iron instead of a lot of splatter.

  16. bad1deas, i know for a fact the cia, nsa, and nambla all watch this site.

    in fact, i think they’re probably on to you.

    you should probably avoid visiting here.

  17. lodestar says:

    Meh, you only need to write zeroes to the drive once and then noone can recover the data.

    • Jason says:

      Irrelevant. You can’t draw any conclusions about the technology based on a sample size of zero. It’s just as reasonable to say that “dd if=/dev/zero of=/dev/sda” is unrecoverable as it is to say that the challenge wasn’t accepted because the reward was pitiful compared to the time and effort required.

      I hereby issue a challenge to the world. To the first person who successfully designs, builds, and demonstrates a way to deposit a 5kg payload at Lagrangian Point 3 goes $20 and an unripe banana. If no one accepts my challenge, then the world will know henceforth that it was impossible.

      See what I mean?

  18. ! Do you have any idea how many greenhouse and toxic gases
    are produced by that? :((

    did you hear that they managed to recover data from a hard
    disk the re-entered the atmosphere with Columbia?

  19. Wolf says:


    Neither model rocket ignighters or fireworks fuses get hot enough to ignight thermite, so far the most reliable way I foud to light it electrically is to take apart a some type of firework that burns brightly and place a small amount of the pyrotechnic mixture in contact with a model rocket ignighter.

    I was planning on making a video about HDD self destruction via thermite after we got talking about it, but It turned out that it actually takes quite a bit of thermite to pierce the shell of an HDD (ie, more than could be kept from piercing the computer case as well), so I deamed the experiment a failure and never put together a vid.

    If I get around to it, I’ll post some vids of my experiments with thermite on utube tomorrow.

  20. Wolf says:

    Sorry about the typos, its hard to ensure your accuracy when you can only see the first 60 charcters or so in each paragraph…

  21. fuzz says:

    braniac did try playing with thermite vs a variety of materials, including ice (I’m sure it’s on youtube somewhere). The only thing that stood up to a flowerpot full was about an inch of tank armour. I suspect the greater mass of a tank of water would make a better heat sink than the equivilent volume of ice (only a few degrees colder), but like you I can’t be bothered to do the maths :)

  22. Aquify says:

    ANyone look at the url at the end of one of the videos? It advertises a porn site. Great work there hackaday.

  23. tehmeh says:

    why not use use the unix dd command to overwrite
    all the data with zeros? I thought they still haven’t found
    a way to recover data from that, simple as it may be.

  24. @Insipid Melon says:

    cia, nsa, and nambla? wtf’s wrong with you? and bdw bad1deas just expresses
    personal opinion so i dunno what might the problem be lawl
    comeone… after him? who’re you to judge? and how come you know for sure, eh?

  25. jeff says:

    quick and dirty source for thermite…

    look up cadwelding or exothermic welding

    any electrical supply house should have
    cadweld shots. These come prepackaged with
    igniting powder at the base of the cylinder.
    They come in a variety of sizes from 45 to
    250 and larger.Be damned careful with them
    though and DO NOT BREATHE IN THE FUMES!!!!


  26. peruser says:

    who knew stochiometry could be so fun?

  27. catch says:

    Maybe Hack a Day should contact a ‘data retrieval’ shop to see if they can actually do what they say they can. If they are such ‘master recovery experts’ It shouldn’t be too hard for them…hahahahahaha

  28. Moejj says:

    hehheheheehhehhhhehhheheeehehhhehhehhhhe fire! fire!! hhheeheheheeehhhehhehehhee
    fire!! hheeheeeheeehheeef fire!! heeehheehheehee fire!!hehheheheehhehhhhehhheheeehehhhehhehhhhe fire! fire!! hhheeheheheeehhhehhehehhee hehheheheehhehhhhehhheheeehehhhehhehhhhe fire! fire!! hhheeheheheeehhhehhehehhee
    fire!! hheeheeeheeehheeef fire!! heeehheehheehee fire!!
    fire!! hheeheeeheeehheeef fire!! heeehheehheehee fire!!

  29. Joe says:

    the broken? The broken.

    Formatting won’t clear it, there is still the data, its just tagged so that it doesn’t show up. Rewriting it allows residual magnetic data to remain so that a electron microscope can read the data. To clear it beyond recovery you need to rewrite with 0′s, 1′s 0′s 1′s 0′s 1′s rand, rand, rand.

    I’ve tried using ammonium nitrate (mixed with two other common but sensitive high explosives) on a hard drive – you’ll need a lot (kilogram?), if its only a little it will leave readable fragments.

    Adding a perchlorate to the mix turns your thermite into flash powder, you idiot.

    also there are no greenhouse gasses produced (until you start setting other things on fire) because Fe2O3+al=>fe+alxox

  30. I agree with nicholas manie… you could have tried to reduce
    the amount of toxic shit you sprayed/burned by removing the drive from the

  31. vector1 says:

    thank you for posting that joe. anyone who feels they have data which is very important to keep out of unwanted hands needs to read up on the latest forensic data recovery techniques and educate themselves. also reading about destruction methods for military classified material might provide some imformation, though the military has been notoriously bad at really protecting data, just making it such a pain to recover that its not valuable anymore to the enemy by the time they get it. the problem is that the government will pursue all avenues to prosecute you, they wont stop like a foreign military might when it becomes too difficult or time consuming.

    if you believe you have reason to go this far in destroying your data, do your homework, for your own protection. in the US at least there are ways to secure your data in such a way that the government cannot recover it legally because of rulings regarding the 5th amendment. and if you were taken to court on suspicion of crimes and they added thermite melting of your hard drive to it, there would be a really big shitstorm headed your way. depending on circumstances they may even charge you with assault on an officer, obstruction of justice, even attempted murder. remember all you have to do is hit a cop car which is chasing you, and youve made an attempt on the officer’s life with a deadly weapon. use the law to your advantage.

    if you live in a country where they just drag you off to a dungeon somewhere and torture you until you confess, then maybe you shouldnt be messing with data that sensitive :P

    also, with enough bits of data collected from ram/flash drives and other sources, they may not be able to prove that you had what they’re looking for, but they might be able to prove you -could have had- it, which might be enough. consider all of the places your data goes when it is accessed. and yes, you can read data from memory long after it has been powered off sometimes, depending on environmental conditions, and even data which has been overwritten. think of the value of a bit in an analog sense, the value of that bit isnt really a 1 or 0 as in strictly one value or another, its either closer to 1 or 0, and based on what kind of data overwrote the data they want to recover, they can build a pattern of the bit values and read what was there before. those old ‘decoder window’ toys, where you view a hidden message with a piece of red cellophane is a good example. you know the data overwriting the message is a given value [in this case the wavelegth of light refracted] and so you use a filter [the window] to remove that, leaving the message.

    if you consider that 0, 0, 1, 0, 1 might physically be represented as 0.34, 0.12, 0.88, 0.21, 0.97 in terms of magnetic field strength, or charge contained, and you know that a new write carries a bias on that device of .7 on avergae, then you would know that the data contained before writing of the current data was likely to be 1, 0, 1 or 0, 1, 1 and you can even tell what might have been stored there one more write previous. considering that you know what is stored there -now- you can build a map of probable overwritten data and prove good enough for a layman judge or jury who doesnt know a bit from an aardvark that youre guilty. this is why smashing your platters is ineffective. even if you tear up a piece of paper, you can put it together without much lost data and prove what it contained. platters are the same, they will piece the fragments together and read them with an electron microscope.

    i hope that kind of makes sense to you, i just woke up… blar, MOAR CAFFIENE.

  32. vector1 says:

    i’d like to see someone do a writeup on how the ‘ironkey’ supposedly overwrites data using that proprietary ‘flash trash’ crap…

  33. Roly says:

    Can we get a bit real about data recovery please? Forensic science is wonderful, particularly now in the recovery of “trace DNA”, but physics is physics.

    These platters have not only been heated to *white* heat, they have been partially *burned* (oxidised) to smoke, partially *vapourised*, and partially splattered about the place as dags ranging own to the microscopic.

    When that main glob finally cools it will be a fruit cake of platter material and actual coating that remains and hasn’t been literally sprayed about the room or gone up in smoke. Good luck in recovering magnetic domains from condensed coating vapour.

  34. Xeracy says:

    hey, thats looks like the stuff that poured out of the twin towers… interesting…

  35. thephysicist says:

    Filling the hard drive case with molten iron is probably the most effective data destruction method there is. When you heat a (ferro)magnetic material above its Curie temperature thermodynamics takes over and the magnetic domains become randomly oriented. Hard drives are usually iron or cobalt based, ie. they are ferromagnetic and therefore subject to that effect. Filling the drive with molten iron is a pretty effective way to raise the magnetized areas on the platters above the Curie point and hence obliterate the data. To add to that, as the iron cools inside the drive it will become somewhat magnetic on its own adding a lot of noise to any magnetic readings you somehow manage to get. This would be dramatically more effective than zeroing your drive.

    If you were really paranoid, as would be implied if you’re considering destroying your hard drive with thermite, add an electromagnet near the drive during the heating process. The external field will bias the magnetic domains in the cooling iron/drive and the noise level in any data left will go through the roof.

    Or better yet, use a changing field or multiple fields.

    If you recover the data, call the Nobel prize committee.

  36. poopysock5 says:

    lol you crazy conspiracy theorist. You could always crash a 767 into your hard drive. that might do the trick

  37. nulloutput says:

    “Thermite is usually used to weld railroad ties together.”

    Railroad ties are usually wooden (sometimes concrete) and used to keep the gauge correct
    while transferring the load into the ballast. I think the word
    you are looking for is rail, or possibly track.

  38. (K)NaB says:

    We, in my line of work, us a a similar mixture called “Cad-weld” to bond bare copper cable (like 500 mcm) to ground rods in sub-stations.

  39. Obvious says:

    TrueCrypt is a far better solution.

  40. sumguy says:

    what I really want to see is someone containing
    thermite so that it might be used for safe data
    destruction. I’ll definitely get around to some
    experiments with refractory cement, but I’d love
    for someone to beat me to it. I imagine a nice
    big cement block that contains a usb hard drive
    and a container of thermite, flip a switch and
    the data is destroyed without a wisp of smoke.

  41. Yosh says:

    Uhmmm… Why not just take the thing apart and toss the platters in the microwave…Toss the circuitboard in the broiler and be done w/ it.. 30 secs on high and those little platters are fried.

    I mean.. By the time you realize the feds are coming
    what do you have 3 mins? Ok I’m going to mix my thermite now… Now mister..Yea you with a suit…Watch me lite this thermite… Hang on let me place my magnesium wick… I’m lighting the torch now… everyone has a microwave or a stove… Also make sure to destroy your motherboard and ram while you are at it… There happens to be some recoverable data there.. Or here is an idea.. obey the laws and be a good little boy and then maybe the government will let you keep their computer… And a little of their money.. And even let you sleep in their clothes in their house..And mow their lawn. ;-)

  42. Nitori says:

    Why not have something that can inject tungsten carbide powder into the drive at a moments notice?
    Combine that with a small app that steps the drive head back and forth and it should physically destroy the magnetic coating very quickly so no one can recover the data.
    Another solution some drives have glass platters it might be possible to rig something that will shatter the platters this must be done while it’s spinning as to completely shatter the platters vs just break them into large chunks.
    This combined with AES encryption should be effective enough to stop most if not all forensics.
    Most stuff on CSI is bullshit they even have trouble recovering data off bios locked drives and it’s very expensive.
    BTW I’m sick of the post 9-11 BS some idiots bring up we need to vote these anti terror a–holes out and get our personal freedoms back.

  43. Stephen says:

    Not environmentally friendly! What hazardous chemicals did you release into the atmosphere doing this?

    Isn’t there a green way to destruct the drive?

  44. jesh says:

    chemicals released:
    iron and aluminum oxide from the thermite.
    aluminum oxide, iron oxide, carbon (burned paper), possibly silica (glass platters) from the drives.
    iron oxide from steel case structure, if you burn the whole case.
    various chemicals from the boards, if the PCB’s are incinerated, depending on the age and ROHS status of the manufacturer and product.

    All in all, not all that bad. Many worse ways to destroy the thing.

    Green disposal of most electronics seems to involve shredding, sorting by reclaimable metal, and reuse.
    If you’re worried about data retrieval, you don’t send said storage device out to be recycled. You have some way to destroy it before it leaves your control.

    MS has locked bins that are then shredded (bin and all, from what I understand) before it leaves the MS campus. And that is just for the servers that host various data.
    Military destruction typically involves drilling holes through stuff.
    The reason thermite is available is for destruction of assets when you don’t have time to do it the slow way. Drop a thermite grenade on top of a locked filing cabinet. All the paperwork inside just became worthless.
    Toss one in a fire safe, and close the door. Depending on how well it is designed, you may just have a self contained incinerator, with no outside damage. All critical information/material now gone.

    Completely aside from the paranoia aspect, thermite is just plain cool to watch go up, and even more impressive in person, when you can look through the hole you just burned through an old wreck!

  45. Any word on how this affects your home owner’s insurance rates?

  46. Joe says:

    @yosh – I’ve seen this done so that it is all a prebuilt assembly. You hit the button and the thermite in the bay’s over the hd ignites and torches it. That way you only need seconds of warning (of course, you’re more likely to light it by accident, but its a trade some are willing to make.

    @thephysicist – awesome. I was trying to work out if that would work like that. Does sufficient concussion also screw up the bias?

  47. nubie says:

    More practically could you use a single platter and a dual lathe to cut all the magnetic media off of both sides?

    Might have to beef up the motor to withstand the strain of the lathe blades, but it should be able to work down to a 2.5″ hard drive no problem, especially if you mount it to the head on the sturdy aluminum part and only use the outside edge of the platter.

    Use a clean room to replace the top of the drive with one containing a thermite payload, and use only a single platter, then shape the thermite load to burn in a path toward the center of the drive, as it spins the metal will fling itself away and be totally destroyed. Just melting the top of the platter and using only the top of the platter for data would work too (there should be sufficient density in current drives for plenty of info).

    What about a “quarter shrinking” coil, bent in a funny pattern to make the magnetic field funky as possible, it should EMF erase the spinning platter just fine :).

    I follow the course of don’t do stuff that would require this sort of behavior, but I am intensely curious as to the truth of these recovery stories.

    It stands to reason that if a company could win the great zero challenge they wouldn’t come forward, as the risk to their business that the increased scrutiny of their clandestine clients would face would be high.

    I don’t see why it isn’t possible to map magnetic currents, and I bet the govmnt has invested millions or possibly billions in it, considering the worth to espionage.

  48. Mark Esler says:

    I like how many comments this one got as compared to the rest :D

  49. nambla says:

    thermite was used in bringing down twin towers – these are just the facts. thermite compounds were found at the site, and videos of the towers burning clearly show the same molten metal spraying reaction as the videos above. Finally, the molten steel at the base of the towers that smoldered for weeks, just like lots and lots thermite would do. whether or not the government did it….well now thats not been proven as fact….so its a theory

  50. yosh says:

    @Joe… Yea I can see it now.. I’d install my hard drive destroyer into my computer get my dream Machine exactly where I want it..I fall asleep at my desk hit the little red button and poof I’m at a bar in the clouds doing Jaegerbombs with Heath Ledger, Elvis, JFK and Princess Diana and they would be wondering if my death was a conspiracy….Yosh OuT.

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