Sunroof Explodes Without Warning

Expert Says It's More Common Than You Think

Glass spontaneously exploding is a concern many 7NEWS viewers have shared.

From table tops, to cookware, to sunroofs, many people said their glass items of simply shattered, unprovoked.

“It sounded like a gun went off in the car,” said Travis Wright.

He and his wife, Brooke, were shocked by the sight and sound of exploding glass while driving down Interstate 25.

“I just remember being scared to death. I really thought there was a gunshot,” Brooke said.

One minute the Wrights were driving down the highway, the next, a loud bang.

“We were immediately covered with glass,” said Travis.

When the couple pulled over they noticed part of their sunroof was missing.

“We have three kids and they generally sit in the back seat. They were fortunately not in the back seat because there was a lot of glass and some large pieces actually in one of the child's seat,” said Travis.

There was no bullet, no rock, no object and no sign of anything that had hit and shattered the glass.

“The sunroof explodes and there is a large hole where there used to be glass and there's no discernable reason why it happened,” said Travis.

“We were thinking what could it be, pulling up our physics 101 classes that we both knew,” said Brooke.

Call7 Investigator Theresa Marchetta went back to class at the Colorado School of Mines to get answers.

“We're using more and more glass. We need it to be stronger and unfortunately when you make glass stronger it also has this tendency to explode. It’s part of the territory,” said Mines chemistry professor Mark Eberhart.

Eberhart is fascinated with why things break. So much so, he wrote a book by the same title.

“We've built glass so it's right on the edge of literally blowing up,” Eberhart said, and he is not just talking about auto glass.

“When I tell you we get all kinds of calls about exploding glass, does that surprise you?” asked Call7 Investigator Theresa Marchetta.

“No,” said Eberhart, “That's one of the things that comes with our use of glass in the world today.”

Eberhart said we are using more glass in larger pieces than ever before and the process that makes it durable requires a fragile balance.

“What makes glass strong,” he said, “we've put the surface of the glass under a great deal of compression. That means we are pushing on it. We put the inside of the glass in tension so the inside of the glass is pulling the outside together. That makes a very strong glass."

Upset that balance between the pressure on the inside and outside of the glass and immediately your glass is vulnerable, Eberhart said.

“What happens is if you just scratch through that little layer of strong glass, the whole thing just goes,” he said.

Wear and tear, how the glass is installed and temperature changes all influence how long glass will last.

“Pretty soon this surface damage gets through that layer or strong glass into the layer of weak glass. As soon as that happens and you just touch it or heat it up or you do something and it's all over. It goes,” said Eberhart.

So, with glass all around, should we worry? Eberhart says no.

”I don't think it's something you should worry about. It’s probably less likely you'll be injured by that than being hit by lightning,” he said.

Still, the Wright's will not be using their new sunroof for a while.

“I don't want to over react, but at the same time, I don't know that I'll be riding, driving the car with the sunroof visible and no barrier between the sunroof and the cabin unless it’s open," Travis said.

To extend the lifespan of glass, Eberhart has these suggestions.

  • Do not put a glass patio table in an area where it gets sun on one side and shade on the other. The temperature difference could cause it to break.
  • Do not use abrasives to clean glass because they can cause tiny scratches or nicks.
  • If glass starts to look milky get rid of it.
  • Make sure any auto glass is mounted with a little space between it and the steel or aluminum frame that holds it to allow the glass to expand when your car heats up.