A Not-So Tempered Response

I just watched another story by a TV reporter about glass. This time, the topic was tempered glass breakage. I give the reporter an A for effort, but it’s a tough concept to understand quickly and completely. It seems in this case, the tempered glass in question was in a car sunroof, but it could just as easily have been in a building or on a table. At the conclusion of the report, any rational person would ask why car makers use tempered glass in sunroofs. Heck, they might ask why we use tempered glass at all.

Broken Glass2It was another attempt to give tempered glass a bad name and yet, I’ve decided the blame for all this is ours. That’s right. It’s on our industry. We have done very little to explain the inherent differences among different types of glass, nor have we offered the advantages and disadvantages of each. I’m tired of tempered getting such a bad rap because no one has set the proper expectations for it.

The expert in this report appeared to be the manager of a local glass warehouse. It would be nice to have some manufacturing and technical experts in the report, but that will most likely never happen. Almost everyone is afraid that their words will come back to haunt them—online, in a court case or some other dark place. That’s a shame.

I think if we explained it, people would understand. Here’s how I’d do it:

“Thank you for your inquiry about tempered glass. There are a myriad of different glass types on the market, each with their own characteristics, advantages and disadvantages. Figuring out which type of glass to use in which application is always an evaluation of major and minor factors.

“Tempered glass is a good product. It is a safety glass that breaks at higher levels of pressure than most glass does. Tempered glass sometimes, though not often, contains nickel sulfide stones. It doesn’t mean the glass has been manufactured incorrectly, it just sometimes occurs naturally as part of the manufacturing process. Those stones, on even rarer occasions, can cause spontaneous breakage.

“Use of laminated glass instead of tempered is a viable alternative in many applications, because laminated tends to hold together upon breakage. But tempered glass can resist very high pressure before it finally does break. And tempered glass is usually more resistant to problems that can be caused by solar heat gain, which is very important in a sunroof. All this taken together is why tempered glass is often used there. I hope this helps you understand why tempered glass sometimes seems to break ‘out of the blue.’”

No one questions when a balloon breaks. It’s just something we know and understand about balloons. No one is to blame, it’s just intrinsic in their nature. And while I am not suggesting that tempered glass is as fragile as a balloon, I am suggesting that we, as an industry, do a better job of explaining the different types of glass and what they can and cannot do. One man’s education is another man’s expose, and if we don’t set our own expectation levels, they will surely be set for us by those less knowledgeable.

3 Responses to “A Not-So Tempered Response”

  1. Great message Deb, but I might suggest we even go further and mention the potential outside factors that could cause breakage. Stones, BB guns, incorrect installation, incorrect frame design, foreign matter in the roof structure surrounding the sunroof/moonroof, or dare I say, meteorites. This matter has been getting much attention over the past few years but it seems the industry has done little to find the cause. We are all under pressure to reduce costs in order to save the car company money. Are too many corners being cut? Are we taking the blame for outside factors? The sunroof/moonroof has been around for decades now. I do not recall a huge number of failures 20 years ago. What has changed? Maybe I am just getting forgetful as I age. Maybe. Maybe not.

  2. Deb Levy says:

    Thanks Dave and your point is well-taken. We have no way of knowing what the glass has endured before breakage. I am guessing the the percentage of failures is pretty similar to what it was 20 years ago. The difference is that there are easier ways to communicate about such failures now, so they look more prevalent. We are just hearing about them more. Thanks for writing!

  3. Chuck Knickerbocker says:


    Part of the issue is that much of the “glass” breakage is in non-construction industries, such as the furniture and appliance businesses. These are businesses not often covered in the glass press, but we often hear about the glass table that shattered, the oven picture window that split (even though it’s not glass, but ceramic).

    May I be so bold as to suggest an upcoming article covering those topics, and spread it around anytime one of those topics comes up? Would that help?


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