# Breaking bulletproof glass. **URL:** \ **Category:** Factual Questions\ **Created:** [September 1, 2002, 3:13am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514 "2002-09-01T03:13:29Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![renigademaster](https://avatars.discourse-cdn.com/v4/letter/r/71c47a/32.png) [@renigademaster](https://boards.straightdope.com/u/renigademaster)\ **Post date:** [September 1, 2002, 3:13am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/1 "2002-09-01T03:13:29Z")
_note, I am not a thief, but am worried about the safety of my friend_ My friend recently put bullet proof (shatterproof) glass on his truck (SUV) windows because he is afraid someone will smash the windows to get to his stereo. (His stereo is worth about 9,500 dollars). I am worried that some day he will accidently flip his truck and the fire department won’t be able to break the windows to help him out. I know you can probly do it with great force, but these windows will take a bullet from a .38 and not be compromised. Is there a simple tool he can carry in his car that would allow him to break a window to get out in an emergency? Ben ---
**Author:** ![Intaglio](https://avatars.discourse-cdn.com/v4/letter/i/71e660/32.png) [@Intaglio](https://boards.straightdope.com/u/Intaglio)\ **Post date:** [September 1, 2002, 3:31am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/2 "2002-09-01T03:31:36Z")
Breaking out from inside…? I don’t think so. I suppose the windows could be designed with quick-releases, but that compromises the security to a large degree. Any glass that can resist an outsider breaking in is going to be damned hard to break out from the the _inside_. It’s still not going to protect the stereo from a semi-determined thief. They’ll just punch the lock or jimmy it. Your friend would be better off achieving ‘security by obscurity’. Disguise it or hide it. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [September 1, 2002, 4:08am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/3 "2002-09-01T04:08:03Z")
**Intaglio** ’s right, but your friend probably won’t listen to reason. Check out [these guys](http://www.uscav.com/) as they probably have something that would work. Like a titanium crowbar for a mere $40! ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [September 1, 2002, 4:09am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/4 "2002-09-01T04:09:55Z")
A chain is only as strong as its weakest link. Any thief that attempts to break in via the glass and finds it “impossible” will explore other options. Unless the doors, locks and the rest of the cab are just as secure as the glass, it would not take a thief that long to break in, steal the truck, drive to some other location, _and then_ figure out why the hell the glass is so tough. Besides, _if_ he survives the crash, and _if_ he survives waiting for help to arrive, the fire department will get in - ever hear of the Jaws of Life? The object of getting out after an accident should be safe, fast and efficient. As for your friend getting out of the cab after an accident, he’s just removed the number one way - via the glass. With a simple glass punch, he could have gotten out in no time flat. But the glass he’s installed would not shatter with a glass punch. He could always adapt a rotary grinder to be plugged into the cigarette lighter - but it must be stored securely right next to him so he can get at it immediately after an accident - and cut his way out. OTOH, if he cannot get out, and help arrives too late, at least he go knowing he created his own glass coffin, complete with music. 😃 ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [September 1, 2002, 9:46am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/5 "2002-09-01T09:46:47Z")
> [@](#): > > OTOH, if he cannot get out, and help arrives too late, at least he go knowing he created his own glass coffin, complete with music… I nominate: _The End_ by the Doors. ~ ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [September 1, 2002, 9:54am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/6 "2002-09-01T09:54:52Z")
I had always assumed that there were some regulations that mandated that windshields (at least) be specifically made out of that easily-shatterable but not shard-producing glass that most autos seem to have. Am I wrong in this? ---
**Author:** ![Doc\_Nickel](https://avatars.discourse-cdn.com/v4/letter/d/5fc32e/32.png) [@Doc\_Nickel](https://boards.straightdope.com/u/Doc_Nickel)\ **Post date:** [September 1, 2002, 10:05am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/7 "2002-09-01T10:05:46Z")
> [@](#): > > \*Originally posted by Doghouse Reilly \* > \*\*I had always assumed that there were some regulations that mandated that windshields (at least) be specifically made out of that easily-shatterable but not shard-producing glass that most autos seem to have. Am I wrong in this? \*\* -Yes, but not entirely. The front windscreen needs to be shatter-resistant, so as to not spray the occupants with fragments. It also needs to retain some measure of clarity after certain impacts, presumably to allow the driver to come to a safe stop. The side windows, however, are tempered so they break up into blocks and cubes, and not slivers, knives and spears like you’d see in conventional home-style window glass. As for the OP, chances are the guy installed Lexan, the most common “bullet _resistant_” plastic. Typically this stuff degrades in exposure to UV sunlight, and loses a significant percentage of it’s strength after a year’s weathering. And the rest are correct. While the windows will very likely deter a “smash-and-grab” thief-of-opprotunity, it will do very little to stop a determined chop-shop scout. If he can’t get in, and still wants it, heck, they’ll just call up the guy with the flatbed truck or the guy with the ‘hidden’, fold-out hydraulic “repo” towing mechanism. ---
**Author:** ![casdave](https://avatars.discourse-cdn.com/v4/letter/c/c6cbf5/32.png) [@casdave](https://boards.straightdope.com/u/casdave)\ **Post date:** [September 1, 2002, 10:25am UTC](https://boards.straightdope.com/t/breaking-bulletproof-glass/126514/8 "2002-09-01T10:25:23Z")
During the attempt to steal the Millenium diamond in London a couple of years ago, the item cncerned was kept within a bulletproof glass exhibition unit. Its a good job that the authorities had switched it for a fake, as the robbers used sledgehammers to break into it.