Is it true that glass is a liquid, slowly trickling downwards - and is this why old stained glass panels are thicker at the bottom? Please be aware that the information provided on this page may be out of date, or otherwise inaccurate due to the passage of time. For more detail, see our Archive and Deletion Policy. I mean people often say this and what they mean is that within a window there are individual pieces of glass which are thicker at the bottom. And the reason for that is a reason to do with the way in which stained glass windows are actually made. And, secondly, it gives you better protection against the weather.
The idea that glass after being formed is in a state of flux concerns the belief, held by many, that because glass is a "super cooled liquid" it actually has a degree of "flow" at temperatures within the human comfort range. This urban legend would have us believe that the windows in colonial homes and in very old stained glass windows are thicker at the bottom than at the top because glass is a "supercooled liquid" and is slowly flowing. Ahh that pesky gravity. The acceptance of that story is not based on fact but on a mythological story that has been circulating for many many years. I read it on the internet so it must be true.
Browse the Library Collection. The glass is thicker on the bottom than it is on the top. I didn't really believe it then, and I don't believe it now. Most often it popped up in college textbooks on general chemistry.