# White Phosphorous Grenades Versus Vehicles **URL:** \ **Category:** Factual Questions\ **Created:** [March 28, 2025, 2:25pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257 "2025-03-28T14:25:42Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [March 28, 2025, 2:25pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/1 "2025-03-28T14:25:42Z")
I’ve heard (apocryphal) stories of how a white phosphorous grenade can burn through a metal plate. Is this true? Could a WP grenade be used to disable a vehicle or artillery piece be being placed on the engine or breach? ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [March 28, 2025, 2:35pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/2 "2025-03-28T14:35:05Z")
Could the stories be confusing white phosphorus and thermite? White phosphorus reaches “only” 800c so isn’t going burn through metal unlike thermite ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 28, 2025, 2:45pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/3 "2025-03-28T14:45:57Z")
> [@griffin1977](#): > > White phosphorus reaches “only” 800c so isn’t going burn through metal unlike thermite “Willie-Pete” munitions can burn at temperatures of up to 2500 °C; hot enough to burn through sheet steel and ignite aluminum armor like that on the Bradley Fighting Vehicle. Stranger ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [March 28, 2025, 5:31pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/4 "2025-03-28T17:31:12Z")
I suspect that thermite is the material I’m remembering. ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [March 28, 2025, 8:50pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/5 "2025-03-28T20:50:35Z")
> [@Stranger\_On\_A\_Train](#): > > “Willie-Pete” munitions can burn at temperatures of up to 2500 °C You may well be right, but as we say in this forum:… cite? > [@Stranger\_On\_A\_Train](#): > > aluminum armor like that on the Bradley Fighting Vehicle. The Bradley Fighting Vehicle has aluminum armor? Really? Seems an odd choice unless it’s perhaps an outer shell intended to trigger incoming munitions before they hit the real armor? ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [March 28, 2025, 9:09pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/6 "2025-03-28T21:09:26Z")
> [@Hypno-Toad](#): > > I suspect that thermite is the material I’m remembering. You don’t want to get either of them on you, but the burn temps are: WP: 800°C/1500°F Thermite: 2200°C/4000°F So thermite is a lot hotter than WP. You can literally set a thermite grenade on an engine block and it will burn completely through from top to bottom in 3-5 minutes. I’m sure a WP grenade dropped down an artillery tube would do a perfectly decent job of disabling it, but thermite is generally the go-to for destroying materiel, while WP is used as a very persuasive argument to help resolve disputes over the occupation of territory. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 28, 2025, 11:18pm UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/7 "2025-03-28T23:18:30Z")
I’ve shot hundreds of WP rockets at targets. Some real, some for practice. Blown up some stuff, set some fires, hurt some people. They can set decent fires when the warhead goes off. I sure don’t want any on my skin, nor do I want to inhale the smoke. The grenades have much smaller charges than the rocket warheads. You’d harm an artillery tube with a grenade. It would not melt and do a “wimpy Wally” sag, but it would not last too many more shots (and maybe zero) before something bad happened when they fired a round. They’re pretty precision inside, and don’t admit of much vandalism before they fail under the violence of the next shot. A WP grenade in a vehicle engine compartment IMO/IME will set all the wiring on fire. And the grease, gunk, and fuel. And the rest of the vehicle. What it _won’t_ do is burn through, or up, the engine itself. Lotta temp, just not enough heat from the small amount of WP fuel. Bottom line: WP is awesome as an incendiary; causing flammable stuff to start self-sustaining burning. It is not a miracle “self-igniting and burns up anything it touches” substance. Far from it. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [March 29, 2025, 3:24am UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/8 "2025-03-29T03:24:20Z")
WP grenades will cause burning as a secondary effect, but that’s not their intended purpose. They are made to produce instant white smoke as opposed to smoke grenades which make more smoke but take more time to get going. Thermite grenades are designed to destroy things by burning them to the ground. They can be set on the hood of the car and burn right through it. Though, it’s best practice to throw it inside the car. One thermite grenade tossed in a car will reduce it to a black frame in no time. > [@xtenkfarpl](#): > > The Bradley Fighting Vehicle has aluminum armor? Aluminum alloys, yes. It also has steel applique armor on parts of the turret and hull as well as a spall liner. It can also receive explosive-reactive armor. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 29, 2025, 4:58am UTC](https://boards.straightdope.com/t/white-phosphorous-grenades-versus-vehicles/1016257/9 "2025-03-29T04:58:40Z")
My understanding is that WP is useful because it is pyrophoric. When a WP munition explodes, all the little pieces of WP fly outward and then catch on fire, setting a wide area ablaze. Not so with Thermite, which requires an ignition source.