Cold Shattering Glass

[Joe Pelonio]

We had snow during the night and it was 28 this morning when a teacher that works with my wife at the local school arrived to work. She got out of her car, slammed the door shut and the opposite window, front passenger side, exploded into a million pieces. Anyone in a climate where it's normally that cold ever see that before?

[Ken Fitzgerald]

Joe.........it's not unheard of but is highly unusual. I had the windshield on a new van crack not explode once in a similar situation but I suspect the windshield was installed with some already present unwarranted stress on it. I've had vehicles down to 18 degrees below zero that didn't do it.

[Kyle Kraft]

I had an experience at the other end of the thermometer. In high school we were scrapping out a car. Me and my buddies wondered what a cutting torch would do to a windshield. Nothing.....at first. About 15 minutes after we made a white hot spot in the middle of the glass it exploded into approximately a zillion little pieces.....pretty cool!!!!

[Joe Pelonio]

I had an experience at the other end of the thermometer. In high school we were scrapping out a car. Me and my buddies wondered what a cutting torch would do to a windshield. Nothing.....at first. About 15 minutes after we made a white hot spot in the middle of the glass it exploded into approximately a zillion little pieces.....pretty cool!!!!
That does sound like fun for high school kids. This lady was quite upset about it though, when it happened to her this morning. Not to mention it's still snowing so her seat is going to be wet until the mobile glass guy gets there.

[John Schreiber]

28 degrees isn't cold. At least it's not cold enough to cause that kind of damage to glass.

I have had something similar happen once before though. A friend had been in the passenger seat and he had rolled the window up not realizing it had come off its track. He just thought it needed a lot of force.

The next morning, I closed the driver's side door and the opposite window flew to pieces. After talking to the auto glass guy (and changing my pants) I figured out that the glass must have been under a lot of stress all night and the small shock of me slamming the door caused it to explode.

[Joe Pelonio]

28 degrees isn't cold. At least it's not cold enough to cause that kind of damage to glass.

I have had something similar happen once before though. A friend had been in the passenger seat and he had rolled the window up not realizing it had come off its track. He just thought it needed a lot of force.

The next morning, I closed the driver's side door and the opposite window flew to pieces. After talking to the auto glass guy (and changing my pants) I figured out that the glass must have been under a lot of stress all night and the small shock of me slamming the door caused it to explode.
Maybe that's what happened to her, 28 is not that bad, considering we've been down to 16 already and that may happen again in the next few days. I though it must have had more to do with the air pressure caused by the closing of the door opposite on a small car. Still that's not normal unless something else was wrong as in your friend's case.

[Perry Holbrook]

Tempered glass can sometimes break easier than regular plate (float) glass. When glass is tempered it is heated to over 1000 and then cooled all in a few minutes. This process put the inter core of the glass under compression or stress. That is why when it breaks it explodes, it's actually releasing the internal stresses.

That's why you can't cut tempered glass.

Perry

[Jeffrey Fusaro]

didn't expect to find a question like this here....

i'm in the auto glass manufacturing business.

it's not likely that this breakage was caused by the temperature. auto glass, and complete car systems, in general, are routinely tested at temperature extremes ranging from -40F (winter in alaska/canada) to +120F (summer in phoenix).

it could have been caused by;

1 - damage to glass surface. was the window scraped to remove ice earlier that morning? if something sharp was used on the glass, the small scratch would lead to a catastrophic failure - even if it happened after the initial damage. the slamming door could have been the proverbial 'straw' that broke the camel's (glass's?) back.

2 - residual stress in the glass. tempered glass is under a delicate balance of compression and tension layers within itself.

too little stress, and the glass is weak, and it may not have the required strength to handle impact, or keep occupants inside the vehicle, in the event of an accident. believe it or not, occupant retention is the primary function of auto glass - followed by keeping the elements out.:D

too much residual stress, and the glass becomes overly brittle and prone to breakage - even when not being impacted or damaged.

in extreme cases, improperly tempered glass can break shortly after being assembled into new cars at the auto assembly plant. DAMHIKT.

[Travis Lavallee]

Didn't happen to my glass today, and it was -48 C with the windchill. About -36 without. I have never even heard of that happening in the winter up here, where -2 C (28 F) is a nice day.