Suddenly Shattered Glass
Most recent answer: 04/08/2016
- Dave (age 60)
This reminds me of a personal story. The rear window of my parents' Volvo spontaneously shattered when the car, only about 20 years old, was sitting in the garage. My dad, who was around 90 at the time just shrugged and said "Well, what can you expect when something is so far out of thermal equilibrium?"
Glass, particularly certain types of tempered glass, has some strong internal strains because parts of it cool and become rigid before other parts, so that the shape doesn't adjust properly as the last parts cool down and shrink. In other words, parts of the glass are compressed more than they would be in equilibrium and other parts are stretched more. Small defects and uneven thermal strains (those little oil lamps?) can sometimes trigger a little crack to start to tear, allowing the shape to change releasing that strain. Typically, for tempered glass that leaves lots of smallish pieces, not just a few big cracks, because there's strain throughout the glass. I guess something like that happened with your platter.
(published on 04/08/2016)