Comment by fatboy

When I was a kid I worked in a double glazing factory. Some of the old timers demonstrated just how hard it is to break a piece of toughened glass to me by whacking one with a bit of wood right in the middle of the pane, really really hard. Nothing happened. Then the dude tapped it really quite gently with a glass breaker in the corner (where it can't flex as much he said) and the whole thing exploded into those little cubes you see on the ground in dodgy car parks.