Originally Posted by dirty_sanchez
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.
You shouldn't repeat that myth, been debunked many times over. Lower caulking gets damaged from condensation dripping down and swelling the wood at the bottom of the pane. Much worse when it freezes then thaw. I have restored enough of them old wavy panes windows, some close to a hundred years old to know.
Couple hundreds of them old panes in my little house and there will be many more when I close in the back porch with them old cedar framed school windows I have to restore someday.
Flowing glass maybe but.....:
Viscosity depends on the chemical composition of the glass. Even germanium oxide glass, which flows more easily than other types, would take 10^32 years (100,000,000,000,000,000,000,000,000,000,000) to sag. Zanotto calculates. Medieval stained glass contains impurities that could lower the viscosity and speed the flow, but even a significant reduction wouldn't alter the conclusion, he remarks, since the age of the universe is only 10^10 (100,000,000,00).
From there and there are many others: