# What is thermite? **URL:** \ **Category:** Factual Questions\ **Created:** [November 3, 2005, 8:24pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346 "2005-11-03T20:24:23Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [November 4, 2005, 2:17am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/21 "2005-11-04T02:17:22Z")
> [@Squink](#): > > It’s not. The stuff is hard to ignite (usually a Mg ribbon or ignition mix), and you end up with a big pile of white hot aluminum oxide in addition to your iron. If you try using it for small projects, you’ll quickly find that the molten iron loses heat too fast to make a decent joint. Ahh. So it burns too fast to heat and melt and mix to the joints being welded. Makes sense. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [November 4, 2005, 2:24am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/22 "2005-11-04T02:24:07Z")
> [@Bosda Di'Chi of Tricor](#): > > Ummm…do not do this at home. > > _ **REALLY!!** _ > > :eek: :eek: :eek: You think that’s fun, try a thermic lance… ---
**Author:** ![JustAnotherGeek](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@JustAnotherGeek](https://boards.straightdope.com/u/JustAnotherGeek)\ **Post date:** [November 4, 2005, 2:46am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/23 "2005-11-04T02:46:56Z")
> [@enipla](#): > > It can’t be that easy. Yes, and then again, no. I found out much to my dismay, and much to my colleague’s amusement\*, if your powder is **even the slightest bit damp** (or has any impurities that will vaporize easily), you get a flash explosion, not a burn. :o Your sample needs to be _really_ dry! When I tried this again (with a fresh sample), I got it to burn straight through a coffee can (upside down over sand). The aluminum of the can bottom melted, dripped, then froze into nifty stalagtites! I even managed to weld the small aluminum pie tin onto the coffee can. Even that, though, took an awful lot of patience getting the dang magnesium to light and catch the thermite. And I made sure that I was over non-combustable material and had a fire extinguisher handy. (Not for the thermite - it has it’s own oxygen supply, but for anything it might have caught.) So basically, I’m saying _do not try this at home!_ \*We are (among other things) chemistry teachers; I was only trying a tiny amount, but, as stated, the podwer was not bone-dry :smack: , and it went **fooomp!** :mad: , and the look on my face was appearently priceless! 😕 But then we both had a good laugh! 😃 ---
**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\ **Post date:** [November 4, 2005, 2:51am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/24 "2005-11-04T02:51:27Z")
> [@Johnny L.A.](#): > > I saw a show on one of the ‘educational’ channels. The premise is that scientists go to some remote location, they’re given tasks to accomplish, and they do them. This is “Rough Science”, by the way. British show. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [November 4, 2005, 3:05am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/25 "2005-11-04T03:05:00Z")
> [@SmackFu](#): > > This is “Rough Science”, by the way. British show. That’s it. Fairly interesting show, though I’ve only seen a couple of episodes of it. So what’s a ‘thermic lance’? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 4, 2005, 3:11am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/26 "2005-11-04T03:11:34Z")
> [@Johnny L.A.](#): > > So what’s a ‘thermic lance’? Slightly different beast. It’s a hollow steel tube loosely packed with thin iron rods or a rolled iron sheet, with oxygen pumped through it. When ignited, the high temperatures of the iron-oxygen combustion reaction can be used to cut through nearly anything, including rock and ceramics. Naturally, everything is consumed in the reaction, including the enclosing tube, so the thing gets shorter and shorter as you cut. It’s pretty spectacular to watch, too. ---
**Author:** ![slaphead](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slaphead](https://boards.straightdope.com/u/slaphead)\ **Post date:** [November 4, 2005, 11:03am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/27 "2005-11-04T11:03:05Z")
> [@Q.E.D.](#): > > When ignited, the high temperatures of the iron-oxygen combustion reaction can be used to cut through nearly anything, including rock and ceramics. For when you absolutely, positively, HAVE to get into that bank vault in a hurry. There are lots of other [uses](http://www.meg.co.uk/meg/app10.htm) , but that’s the context most often mentioned, curtesy of Hollywood. ---
**Author:** ![Mr.Goob](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@Mr.Goob](https://boards.straightdope.com/u/Mr.Goob)\ **Post date:** [November 4, 2005, 2:10pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/28 "2005-11-04T14:10:04Z")
> [@Q.E.D.](#): > > Slightly different beast. It’s a hollow steel tube loosely packed with thin iron rods or a rolled iron sheet, with oxygen pumped through it. When ignited, the high temperatures of the iron-oxygen combustion reaction can be used to cut through nearly anything, including rock and ceramics. Naturally, everything is consumed in the reaction, including the enclosing tube, so the thing gets shorter and shorter as you cut. It’s pretty spectacular to watch, too. I can’t remember what the Navy called these things. We had one on my aircraft carrier around '88 or '89 to be used for emergency access if we had to go through a bulkhead. The first time I saw it used we all looked like this :eek: A really cool very expensive piece of equipment. -time to do some online shopping… ---
**Author:** ![mazinger\_z](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@mazinger\_z](https://boards.straightdope.com/u/mazinger_z)\ **Post date:** [November 4, 2005, 4:52pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/29 "2005-11-04T16:52:08Z")
What? No references to Batman? It’s Batman’s all-purpose incindiary device. IRL, it’s the stuff that people already posted about. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [November 4, 2005, 5:20pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/30 "2005-11-04T17:20:04Z")
> [@slaphead](#): > > For when you absolutely, positively, HAVE to get into that bank vault in a hurry. Thermic lances are for girls. Real men manipulate it. 😉 ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [November 4, 2005, 6:49pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/31 "2005-11-04T18:49:15Z")
> [@Jurph](#): > > Terminology nitpick: only liquid-fueled rockets have “engines”. When I was doing ballistic missile research, we were very specific to call the solid boosters “motors”. On this distinction, outside of rocketry, I was under the impression that the difference between motor and engine was whether it propelled itself or not. A table saw has a motor and a car has an engine. I guess another “fact” I thought I knew is flying out the fricking window… ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 4, 2005, 7:33pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/32 "2005-11-04T19:33:38Z")
> [@Kevbo](#): > > The iron oxide is iron oxilate I think (may be getting this mixed up with jewler’s rouge though) which has an extra oxygen atom or two over garden variety rust. > > The aluminum has a greater affinity for the oxygen than the iron, So in the burning, the aluminum scavanges the oxygen, leaving iron… so the iron oxilate/oxide is reduced to molten iron. Nitpick: oxalate ion is C[sub]2[/sub]O[sub]4[/sub][sup]2-[/sup]. Oxide ion is O[sup]2-[/sup]. You are probably thinking of iron(II) oxide (FeO) vs. iron(III) oxide (Fe[sub]2[/sub]O[sub]3[/sub]). ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [November 4, 2005, 8:11pm UTC](https://boards.straightdope.com/t/what-is-thermite/329346/33 "2005-11-04T20:11:07Z")
I have heard the thermic lance referred to as an _oxygen lance_. It’s funny that “the Thing” (1951) was on TCM this morning. They use a thermite bomb to melt the flying saucer out of the ice. (And destroy the saucer in the process). ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [November 5, 2005, 12:02am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/34 "2005-11-05T00:02:57Z")
The other name by which they are known is ‘burning bar’. Rent the 1981 movie ‘Thief’ starring James Caan to see him take on a pressure-style vault door using a burning bar. Speaking as a former bank equipment guy, it’s technically one of the better films made. 😉 ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [November 5, 2005, 12:23am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/35 "2005-11-05T00:23:46Z")
> [@Mr. Goob](#): > > I can’t remember what the Navy called these things. We had one on my aircraft carrier around '88 or '89 to be used for emergency access if we had to go through a bulkhead. The first time I saw it used we all looked like this :eek: > > A really cool very expensive piece of equipment. > > -time to do some online shopping… That would be a [Portable Emergency Cutting Unit](http://www.dcfp.navy.mil/library/dctricks/DCTrick015.htm), and let me just say that those things are freaking awesome. ---
**Author:** ![Dr.Rieux](https://avatars.discourse-cdn.com/v4/letter/d/aeb1de/32.png) [@Dr.Rieux](https://boards.straightdope.com/u/Dr.Rieux)\ **Post date:** [November 5, 2005, 1:15am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/36 "2005-11-05T01:15:40Z")
IIRC, Doc Savage used to wear vest buttons made of thermite–handy for those obligatory escape scenes. ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [November 5, 2005, 1:30am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/37 "2005-11-05T01:30:03Z")
> [@danceswithcats](#): > > The other name by which they are known is ‘burning bar’. Rent the 1981 movie ‘Thief’ starring James Caan to see him take on a pressure-style vault door using a burning bar. Speaking as a former bank equipment guy, it’s technically one of the better films made. 😉 Damn you danceswithcats, I’ve been waiting for someone to make a movie reference so I could throw that in! ☹🙂 ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [November 5, 2005, 2:16am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/38 "2005-11-05T02:16:59Z")
> [@FordPrefect](#): > > On this distinction, outside of rocketry, I was under the impression that the difference between motor and engine was whether it propelled itself or not. A table saw has a motor and a car has an engine. I guess another “fact” I thought I knew is flying out the fricking window… Yup, even engineers can’t always agree what’s an “engine” or a “motor” in some cases. It’s sort of like that whole “Is Pluto a planet or not?” debate. ---
**Author:** ![stanger](https://avatars.discourse-cdn.com/v4/letter/s/7ba0ec/32.png) [@stanger](https://boards.straightdope.com/u/stanger)\ **Post date:** [November 5, 2005, 2:19am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/39 "2005-11-05T02:19:26Z")
I read in a book some years ago about a guy who said he put a pile of thermite on the hood of an old junk car, ignited it, and watched it burn through the hood and engine down to the ground :eek: No mention of how large the pile was, however. Is this possible? From what I have read here, the reaction is too quick or would require a large pile of thermite to burn long and hard enough to do this. Am I wrong or is the burning that long and intense? ---
**Author:** ![Omphaloskeptic](https://avatars.discourse-cdn.com/v4/letter/o/bcef8e/32.png) [@Omphaloskeptic](https://boards.straightdope.com/u/Omphaloskeptic)\ **Post date:** [November 5, 2005, 2:31am UTC](https://boards.straightdope.com/t/what-is-thermite/329346/40 "2005-11-05T02:31:34Z")
> [@stanger](#): > > I read in a book some years ago about a guy who said he put a pile of thermite on the hood of an old junk car, ignited it, and watched it burn through the hood and engine down to the ground :eek: No mention of how large the pile was, however. > > Is this possible? From what I have read here, the reaction is too quick or would require a large pile of thermite to burn long and hard enough to do this. Am I wrong or is the burning that long and intense? Was it a [VW Beetle](http://pubs.acs.org/cen/80th/magnesium.html), by chance? That might make a somewhat spectacular display. [Previous page](https://boards.straightdope.com/t/what-is-thermite/329346.md?page=1)