24 August 2012

Exploding household glass

Some glass objects don't just break or shatter - they truly "explode."  I noticed a story at BoingBoing this morning: Dining room table spontaneously "exploded"-
On a recent Seattle morning, Adam Welch heard an crashing sound and saw broken glass everywhere. Turned out that his dining room had table spontaneously shattered...
There are a number of useful comments at the thread, particularly this one:
Tempered and heat strengthened glass can explode due to nickel sulfide inclusions, which are basically bits of nickel sulfide in the glass that change state slowly after being heated up during the tempering process. Because tempered glass is strong due to the fact that the outer layers are in compression and the inner in tension (kind of a two dimensional truss structure, when there is a small failure all the stored energy is released rather quickly. Interestingly enough, there was a rather spectacular failure of a large sheet of tempered glass in the dinosaur hall of the Museum of Natural History in NYC about a decade ago. You can actually go through the shattered dice of tempered glass that fails in this way and find the point of failure; it will create two round dice that meet at the point where the inclusion was, these dice are quite different than the rest of the pieces which tend to be square.
Another comment reminded me of my own post four years ago - Why do teardrops explode?  That post includes two impressive videos of Prince Rupert's drops exploding.

After reading the BoingBoing post and my old one, I searched YouTube for relevant videos and found several.  A Massachusetts TV channel reported on exploding patio tables in 2007, and exploding shower doors in 2009 [embedding disabled because by some convoluted logic they want it viewed on YouTube but not on blogs??], but here's one documenting the aftermath of an exploding bathroom vanity:

It's not apparently a predictable event, but the knowledge that it can happen may be useful when making decorating or remodeling decisions.


  1. I was sitting next to a sheet of tempered glass at the airport in Milwaukee that exploded for no reason.

    Was a pretty tense scene given that it was at the airport.

  2. My physics teacher used to demonstrate the teardrop behavior using a simple coke bottle.

    An explanation here:
    A link to video here:

  3. Actually, if a piece of glass is not completely, totally, homogeneous in terms of it's thermal expansion rating, it is nearly destined to eventually blow up or shatter spontaneously. Something I learned working with art glass. It can happen with cheaper glass from unknown origins, or even with expensive glass where small mistakes are made.

  4. While in college I worked at an arcade. One of my tasks was to clean the playing surface of the pinball machines. This involved removed the tempered glass tops, then sliding them back on after cleaning was complete.

    One day, I picked up the sheet of glass to slide it back in, and it just exploded in my hands, showering small chunks of glass everywhere, but mostly into the pinball machine itself. I just closed my eyes when the explosion happened, and when I opened them, I was standing in the middle of a pile of glass, holding a chunk in each hand with empty space in between. There was not a scratch on me.

  5. My two experiences:
    1. Family gathering when 'Microwave safe' glass was still a new thing. The hot glass was placed on the cool dining room table and *BooM* - meal cancelled, everyone and thing covered in glass, complete mess, no injuries.
    2. Family gathering, hot food placed on glass coffee table... *BooM*
    You would think I would have learned by now but I am typing at a desk that is also glass... No hot drinks allowed?


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