# How does plastic explosive work? **URL:** \ **Category:** Factual Questions\ **Created:** [June 9, 2003, 8:15pm UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707 "2003-06-09T20:15:52Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Interrobang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/interrobang/32/17463_2.png) [@Interrobang](https://boards.straightdope.com/u/Interrobang)\ **Post date:** [June 9, 2003, 8:15pm UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/1 "2003-06-09T20:15:52Z")
I was watching a movie the other day that featured a terrorist using some plastic explosive to blow up a building. I realized that, although I know what plastic explosive is, I have no idea how it works. How it’s used in this movie: wad of plastic explosive has an electrical wire stuck into it. Timer is connected to wire. At a specific time, an electric charge is triggered, which ignites the plastic explosive, which blows up in spectacular fashion. My questions: Is this accurate, oversimplified, or just plain wrong? Is plastic explosive basically stable until an electrical charge or other trigger is applied to it? Are there multiple varieties of plastic explosive? And what happens to the plastic explosive after it explodes? Is it all vaporized? Most of it? Only a little bit of it? What traces are left? ---
**Author:** ![SteveAtlanta](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@SteveAtlanta](https://boards.straightdope.com/u/SteveAtlanta)\ **Post date:** [June 9, 2003, 8:42pm UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/2 "2003-06-09T20:42:19Z")
It’s much the same as a solid explosive, except that it is formable, like modeling clay. It is also very stable. Shooting it with a bullet normally won’t set it off, though I would discourage people from carrying out that experiment. The electrical wires you describe connect to a blasting cap, a metal straw which holds a chemical that emits a very sharp, hot blast when ignited by the heat of a small amount of electricity flowing from a battery. The sharp, hot explosion initiates the explosion in the plastic explosive, just like it would initiate an explosion in dynamite or some other explosive. I don’t think the blasting caps for plastic explosive are any different than those for dynamite. There is residue from an explosive like plastic or dynamite. However, it is slight. Most of the material burns up. However, there is enough residue that crime scene investigators can wipe it up, study it, then determine what explosive the residue came from. Also, some explosives contain small amounts of indestructible particles that can be recovered to determine the manufacturer and even batch from which the explosive came. That information can lead to an entire chain of possession, from manufacturer to dealer to, perhaps, the end user. Speaking specifically of C4 plastic explosive, soldiers report that it is stable enough that a sheet can be sliced off (similar in dimensions to one of those indiviually wrapped cheese slices in the grocery store) and lit using a match to make a hot little fire for warming some food, boots or hands. Note: The information I’ve typed above is based on what I learned from my grandfather, who was a “powder monkey,” or blasting specialist in his civilian life. He worked mainly with traditional stick dynamite. ---
**Author:** ![sishoch](https://avatars.discourse-cdn.com/v4/letter/s/3e96dc/32.png) [@sishoch](https://boards.straightdope.com/u/sishoch)\ **Post date:** [June 9, 2003, 8:57pm UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/3 "2003-06-09T20:57:08Z")
That is a rather simplified explaination, but yes, that’s how it’s done (the electric wire is attached to a detonator in the explosive) except that plastic explosives do not go off in spectacular fashion. Pyrotechnics are added to get the pretty colors for the camera. Often the “explosions” you see in the movies are pure pyrotechnics, about as destructive as fireworks. Watch an implosion sometime, all you see are puffs of smoke. Yes, they’re designed just that way. You could strike some of them with a hammer and they wouldn’t go off. I don’t think I’ll try it myself, however. Yes, many varieties, such as Comp C4 and Semtec. All tightly controlled and illegal for unlicensed use. Trace amounts can be found, but most will be consumed. You can (unfortunately) find all of this and a lot more with a little research. I will warn you that the directions on some sites are quite dangerous. If you really want to know how to blow thing up, go to blasting school and become a professional. ---
**Author:** ![UncleBill](https://avatars.discourse-cdn.com/v4/letter/u/d26b3c/32.png) [@UncleBill](https://boards.straightdope.com/u/UncleBill)\ **Post date:** [June 9, 2003, 10:37pm UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/4 "2003-06-09T22:37:52Z")
C-4 can be and has been used to heat meals, although it is highly NOT recommended. It can be smashed and molded and stepped on, too. BUT DO NOT DO BOTH AT THE SAME TIME. It takes heat AND pressure to explode, so somebody stepping on burning bit of C-4 used to heat food will likely lose a foot, or at least a part thereof. C-4 can be pushed into a crack, or molded into a shape to focus the main force of the blast in a certain area, or away from a certain area. It’s mystique is its portability and concealability, not its power. ---
**Author:** ![Paul\_in\_Qatar](https://avatars.discourse-cdn.com/v4/letter/p/ccd318/32.png) [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)\ **Post date:** [June 10, 2003, 1:58am UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/5 "2003-06-10T01:58:31Z")
You see plastic explosives (such as the first one, dynamite) are a matrix which holds in place a traditional explosive (in the case of dynamite, nitroglycerin). The plastic matrix allows the mass to be handled safely and be formed into various shapes. The blob has to be delivered a blow, like the shock of a balsting cap, to release the nitro from its stabilizer and allow it to explode. sishoch is of course right, movie explosions are grand things, generally augmented by lots of gasoline and other neat stuff and then shown in glorious slow-motion. The real thing is not all that impressive. Still neat though. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [June 10, 2003, 3:58am UTC](https://boards.straightdope.com/t/how-does-plastic-explosive-work/180707/6 "2003-06-10T03:58:08Z")
How Stuff Works > **[How C-4 Works](https://science.howstuffworks.com/c-4.htm)** > > C-4 is in the news quite a bit these days -- it's a powerful explosive that's used in terrorist attacks all over the world. Find out what C-4 explosive is and what it can do.