# Is Glass a solid or a liquid **URL:** \ **Category:** Factual Questions\ **Created:** [March 14, 2012, 8:06pm UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778 "2012-03-14T20:06:06Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Raygun99](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@Raygun99](https://boards.straightdope.com/u/Raygun99)\ **Post date:** [March 15, 2012, 6:58pm UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/21 "2012-03-15T18:58:01Z")
> [@Siam\_Sam](#): > > My college geography professor – yes, geography – claimed it was liquid. Said it keeps flowing, and the bottoms of windows grow slightly thicker over time as a result. How convenient then, that the bottom of window panes were made just wide enough for how thick they’d get. ---
**Author:** ![Dufus](https://avatars.discourse-cdn.com/v4/letter/d/c77e96/32.png) [@Dufus](https://boards.straightdope.com/u/Dufus)\ **Post date:** [March 16, 2012, 12:03am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/22 "2012-03-16T00:03:50Z")
> [@](#): > > With that nails-on-a-wall experiment, you could see similar results with any number of materials that inelestically bend under their own weight. But we wouldn’t call those materials “liquid”, we would call them “ductile” or “plastic”. > [@](#): > > I understand a steel bar can be made which will bend under its own weight, and no one contends that it’s a liquid. 4 feet of steel tubing will flex under it’s own weight, but it’s not going to keep flowing under its own weight over time. It might make a good MythBusters experiment or, if someone has the desire to do it at home, measure the sag in a piece of thin-wall glass tubing after x number of months/years compared with the sag in a piece of steel tubing. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [March 16, 2012, 12:39am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/23 "2012-03-16T00:39:42Z")
> [@Dufus](#): > > 4 feet of steel tubing will flex under it’s own weight, but it’s not going to keep flowing under its own weight over time. > > It might make a good MythBusters experiment or, if someone has the desire to do it at home, measure the sag in a piece of thin-wall glass tubing after x number of months/years compared with the sag in a piece of steel tubing. A length of some heavy and ductile material like lead would definitely inelastically deform under its own weight. And I bet you could achieve the same with steel, with the right material dimensions – though that might involve a pretty thin ribbon ---
**Author:** ![Dufus](https://avatars.discourse-cdn.com/v4/letter/d/c77e96/32.png) [@Dufus](https://boards.straightdope.com/u/Dufus)\ **Post date:** [March 16, 2012, 12:57am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/24 "2012-03-16T00:57:09Z")
> [@lazybratsche](#): > > And I bet you could achieve the same with steel, with the right material dimensions – though that might involve a pretty thin ribbon Just for the sake of determining the answer to the OP’s question, don’t you think the dimensions of the steel tubing should be the same as the dimensions of the glass tubing? ---
**Author:** ![Michael63129](https://avatars.discourse-cdn.com/v4/letter/m/3da27b/32.png) [@Michael63129](https://boards.straightdope.com/u/Michael63129)\ **Post date:** [March 16, 2012, 1:10am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/25 "2012-03-16T01:10:12Z")
If a thin glass tube keeps bending under its own weight, then how come light bulbs and the like (large CRTS can have 10 tons or more of pressure on them) don’t slowly implode; we have light bulbs [over 1 century old](http://www.centennialbulb.org/) that haven’t noticeably deformed (and operating all that time, so warmer than room temperature). That said, as others have noted, many other materials, whether metal, plastic or wood, will bend under their weight if not supported, with the bending slowly increasing (at a decreasing rate) over time until some equilibrium occurs, and remain bent if left in position long enough. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [March 16, 2012, 1:12am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/26 "2012-03-16T01:12:25Z")
> [@Raygun99](#): > > How convenient then, that the bottom of window panes were made just wide enough for how thick they’d get. We have much to learn from these ancient and wise cultures. ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [March 16, 2012, 2:54am UTC](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778/27 "2012-03-16T02:54:12Z")
I see I’ll have to journey to my old uni and measure the bottoms of the windows on campus. Will probably set off a terrorist alert or something. [Previous page](https://boards.straightdope.com/t/is-glass-a-solid-or-a-liquid/615778.md?page=1)