Originally Posted by DC2wheels
It probably has something to do with the fact that glass is actually a "super-cooled liquid"?
It VERY SLOWLY flows. Look at a very old pane of glass- it is thicker at the bottom than at the top.
Ding Ding Ding!!!! Circle gets the square!
Glass is actually a liquid. Liquids are tough to bond.
If you ever go into very old houses-the kind that still have wavy glass that has it's original window caulking, more often than not the caulking near the bottom of the pane has been busted out, while the caulking at the top is still in good shape. This happens because the glass settles or sags over long periods of time.