A popular world-wide myth about inorganic glasses based on silica frameworks, such as glass windows in cathedrals, is that over hundreds of years noticeable flow is able to occur under the influence of gravity, as a result of which cathedral glass windows are thicker at the bottom than the top.

Is cathedral glass see through?

Cathedral is a translucent glass that allows light to pass through making it ideal for doors, windows, dividers, and glass ornaments.

Does glass flow under gravity?

The Answer: For years people have looked at 12th century medieval glass windows and determined that the reason some are thick at the bottom is that over time gravity causes the glass to "flow" towards the bottom of the frame.