Glass cup shattered on its own, anyone have an explanation?
A glass cup was sitting on the table. Not sure for how long but not too long. The Air Conditioner was on and I accidentally tapped it lightly and it shattered completely. This was totally freaky, and was only wondering if anyone had an explanation to this.
11 months ago Report Abuse by Fizzle Member since:
October 08, 2006
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A few things could have happened depending on the type of glass. If the glass was cold and exploded into sharp slivers, it was probably Corelle or a similar glass. These are thin but strong. The strength comes from rapid chilling from the molten state. The surface hardens, so when the interior cools and contracts it draws the surface tightly inward. It's that tension that makes the strength, but there's a lot of residual stress--it's a tightly bound spring. If the surface is broken, that stress is released all at one and they can really explode.
If it was a heat resistant glass like Pyrex, I've heard stories that pieces manufactured years ago are more stable but newer pieces tend to shatter occasionally. Boron is added to reduce expansion which is why they're heat resistant, but these pieces tend to be thicker and if the factory used the low expansion as an excuse to cool the pieces more quickly, you'll have internal stresses similar to Corelle.
Now for the trigger. Glass accumulates scratches from normal use even if you can't see them. These scratches are weak spots, and if a scratch is at a point in the glass where there's a lot of residual stress it forms a traveling crack. The crack will follow the stress, literally unzipping that tightly bound spring that I mentioned earlier. The crack travels at several times the speed of sound and can spread outward, exploiting other weak points (scratches with stress underneath). We see it as unexpected explosive shattering.
That light tap was all it took to pull the trigger.
Plain glass also accumulates surface scratches and can break with only a light tap, but it's much less likely because they aren't manufactured with stress on purpose. A crack will follow weakness in the glass and you'll get a few solid pieces. But it can happen and this is the reason you shouldn't put your hand inside a glass to wash it. Use a brush.
11 months ago Report Abuse Asker's Rating: Asker's Comment: Thanks alot for that, I had no clue what caused it, but with your explanation aswell as everyone here, am more aware of why it happened. And no it was not cracked, but he said small tears from wear must have caused some of it
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A glass cup was sitting on the table. Not sure for how long but not too long. The Air Conditioner was on and I accidentally tapped it lightly and it shattered completely. This was totally freaky, and was only wondering if anyone had an explanation to this.
11 months ago Report Abuse by Fizzle Member since:
October 08, 2006
Total points:
33,632 (Level 7)
Add Contact
Block
Best Answer - Chosen by Asker
A few things could have happened depending on the type of glass. If the glass was cold and exploded into sharp slivers, it was probably Corelle or a similar glass. These are thin but strong. The strength comes from rapid chilling from the molten state. The surface hardens, so when the interior cools and contracts it draws the surface tightly inward. It's that tension that makes the strength, but there's a lot of residual stress--it's a tightly bound spring. If the surface is broken, that stress is released all at one and they can really explode.
If it was a heat resistant glass like Pyrex, I've heard stories that pieces manufactured years ago are more stable but newer pieces tend to shatter occasionally. Boron is added to reduce expansion which is why they're heat resistant, but these pieces tend to be thicker and if the factory used the low expansion as an excuse to cool the pieces more quickly, you'll have internal stresses similar to Corelle.
Now for the trigger. Glass accumulates scratches from normal use even if you can't see them. These scratches are weak spots, and if a scratch is at a point in the glass where there's a lot of residual stress it forms a traveling crack. The crack will follow the stress, literally unzipping that tightly bound spring that I mentioned earlier. The crack travels at several times the speed of sound and can spread outward, exploiting other weak points (scratches with stress underneath). We see it as unexpected explosive shattering.
That light tap was all it took to pull the trigger.
Plain glass also accumulates surface scratches and can break with only a light tap, but it's much less likely because they aren't manufactured with stress on purpose. A crack will follow weakness in the glass and you'll get a few solid pieces. But it can happen and this is the reason you shouldn't put your hand inside a glass to wash it. Use a brush.
11 months ago Report Abuse Asker's Rating: Asker's Comment: Thanks alot for that, I had no clue what caused it, but with your explanation aswell as everyone here, am more aware of why it happened. And no it was not cracked, but he said small tears from wear must have caused some of it
There are currently no comments for this question.
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