Spontaneous disintegration of car window?

The passenger window broke into thousands of crumbles while driving at 55 MPH in a rural area. The sight and sound were quite a shock. I was 60 miles from home.

I called 911 and a county officer was there quickly. He said he had heard of this kind of thing. I wondered if a bullet had done it. We did not see any exit hole or damage. I went back to a glass shop and they vacuumed the car and put in a temporary plastic covering. When I got home I looked more carefully and saw quite a few tiny chips of missing paint on the passenger side. I am quite sure they had not been there prior.

Could the crumbles of glass done this damage to the paint? Or a shotgun blast? Or…?

Window glass is tempered glass. Which means it’s pretty tough to shatter when struck on the surface. But if it’s struck on the edge or if any force is applied to the edge it shatters very easily.

I’ve seen this happen. When I was a kid my mother arrived home after grocery shopping. She sent us kids out to get the groceries from out of the trunk. I removed the last bag out of the trunk and when I slammed the trunk lid shut, the rear window glass exploded into thousands of bits of glass and it all fell into the back seat. This was so loud that my mother heard inside the house. She came out and really got upset with me blaming me for the broken window. So she had me start cleaning up the glass. At this time my father arrived home and saw the broken window and asked what had happened. When I told him he said I had done nothing wrong and this can happen to tempered glass at anytime. He went into the house and explained this to my mother. She wasn’t upset with me anymore.

So yes. If pressure or a blow is applied to the edge of tempered glass it will explode and scare the crap out of ya.


Thanks, Tester. I should have mentioned that the window was completely shut when this happened; that plus the paint damage make me wonder if this was a shotgun blast.

If it were shotgun blast there would be dimples/holes in the body. Plus there would be shot from the shotgun shell inside the vehicle.


A pebble may have hit it at another time and the crack finally grew long enough for the window to shatter. I had this happen with a shower door. I was asleep and heard the boom. I ran into the bathroom to find a floor full of glass pebbles. It was probably internal stress induced during manufacturing. That is another possibility for you window.

You could have someone familiar with shotgun ballistics examine the paint damage…Shotshell damage will be very distinctive, depending on shot size and distance from shooter…

While it does not happen very often, car windows can and do disintegrate for no apparent reason…Internal stress in the glass or thermal shock can do it…A kid with a slingshot can cause the exact same damage so it can be very hard to pin down…

It wouldn’t be that unusual for this to happen just due to a defect in the glass or how it is mounted. A little bump or wind gust could be enough to trigger tis to happen in this type of safety glass. I’m not saying it wasn’t caused by someone shooting at your car, but unless you have a reason to think otherwise, consider that the sound of hooves on the ground your hear to be causes by horses, not zebras.

I do not doubt all the previous responses, HOWEVER…

A few years ago my Dad, rest his soul, had a right front window “spontaneously disintegrate” as he entered a parking garage. The glass repair person came to Dad’s house and managed to replace the glass, but couldn’t get the window to move up/down properly because something was bent. Dad had me take the car to a body shop, where they pointed out the scrapes on the leading edge of the passenger-side mirror.

Dad had clipped the garage entryway with the mirror, bending the window frame, and breaking the glass.

Could your paint chips have come from clipping something on the roadside (like the tree that jumped out at me one night, going up I-70 toward Breezewood)?

[BTW, I researched the issue here back then. Found the same kinds of info as now.]

My dad had a similar incident with his 1988 Plymouth Grand Voyager a couple years ago, the van was parked next to the driveway with his newer CRV parked next to it about 100 feet from the gravel road that they share, none of those who were home saw exactly what caused the window to shatter just the glass laying on the ground in two directions (to the side and rear) it seems to happen on these minivans without warning

Automobile glass, like most glass, has internal stresses in it due to the manufacturing process, but it also has impurities in it. I think microscopic bits of nickel stay in the glass and are impossible to get out. These impurities sometimes lead to spontaneous random cracks, which for tempered glass means instant crumble. It’s my understanding that the glass industry as a whole is struggling with an increasing number of glass failures due to this problem.

I have no way of knowing what caused your window to break but I will say this. As a mechanic, I’ve replaced several windows that spontaneously shattered and even had this happen to a car of mine some years back.

In my case, I had just backed my Subaru out from the post office and noticed the driver’s door was not shut all the way. Still rolling backwards, I opened the door, slammed it shut, and the glass in the rear door shattered into bits.

And no, there was no one else around and no stray gunshot could have done it because the post office building is very close to the curb and the car was near parallel to the building.
Unless it was a disgruntled postmaster… :slight_smile:


“A kid with a slingshot can cause the exact same damage so it can be very hard to pin down . . .”

Happy childhood memories . . . ?

Yeah I’ve been shot at before so it does happen. I would think a body shop would be able to tell if the paint marks are from shot pellets. I certainly would have thought the police would have been able to tell. Pellet marks though are hard to fix because the metal stretches so much. And yes the window can spontaneously combust too from previous damage, heat, etc. At this point it doesn’t really matter, you just need to get the window fixed.

A friend had his drivers’ side window shatter when a semi passed him on the highway.
I had a lukewarm drinking glass explode in my hand when I picked it up from a dish rack.
Shards of glass landed more then 10ft away but amazingly missed my face and eyes.

I had an old Pontiac wagon exploded a window once. I had put a whole lot of cardboard in it, to dispose of when I had time. Cardboard absorbs solar heat at a very high rate of efficiency, and it was obvious that localized heat had stressed the window.

Off topic but related to the original post… I was once setting the table for dinner when I was 12 years old. I had the drinking glasses (tempered, just like car windows) in my hands when one of them spontaneously exploded into little chunks. My parents thought I had dropped it but they believed me once they saw that nothing remained but little chunks, none bigger than a quarter of an inch. That experience always makes me nervous when opening car windows on the highway but I have not yet had a car window explode like the OP did.

When in Malaysia I had a Proton Waja (warmed over older Mitsubishi model) as a company car. One day on a perfectly normal 90 degree day there, I slammed one of the doors a little too hard and had the same happen; the door shattered into a thousand pieces.

Some blame poor tempering of the glass causing residual stresses. In our house years ago we had a really nice storm door with a one piece tempered glass panel, removable and replaced with a screen in the summer. My temperamental 3 year old daughter kicked the door with her soft shoes and the same happened.

Thanks, all, for your comments. My shotgun hypothesis seems shakier than it did when I first saw the damaged paint. I think some of the crumbles of glass, whipped alongside the vehicle at highway speed, could have had enough force to break off small chips of paint below and behind the broken window, but not enough force to create any dents.

My windshield got hit by a rock one time. Left a slight crack in the windshield, but never spidered out. Till I hit an extra large June Bug and it instantly spidered to the point I couldn’t see enough to drive the car. Rock ok, June Bug no…go figure…

A guy at work was in a pickup and had slammed the door and the rear window shattered, the truck was a year old and it was a solid rear window not a slider. It happens.

If a shotgun blew the window out you would see it in the paint since it would be almost impossible to only hit the window, its a very distinctive mark, so you should be able to get someone to look at it and tell you for sure.