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Glass a liquid at room temperature?

To the best of your knowledge, is glass a liquid at room temperature?

  • Yep

    Votes: 32 33.7%
  • Nope

    Votes: 38 40.0%
  • That's what I been tole since I were a little baby

    Votes: 8 8.4%
  • I'm staying out of this

    Votes: 7 7.4%
  • I'm keeping my bottled beer in the fridge, just in case

    Votes: 16 16.8%

  • Total voters
Probably about 1985 I read an article in Scientific American that made a great case that glass is indeed a "liquid".
No longer have the mag, and SciAm site doesn't seem to have archived that far back.

Today's SciAm (sciam.com) does have a couple references, here:

Mention is made that one way to make panes was to blow a cylinder and unroll it and cut the panes from that. That might still not make flat panes, but it should have helped to keep the pane from looking like a portion of a Fresnel lens.

Why would glaziers have put the panes in thick side down in every instance?

Why would you assume that any ancient glass goblet retain its original form, when no one actually knows what form it was in its antiquity? I don't think that any patterns or plans exist that gave specs as to the tenth of a thou what the dimensions were when produced.

Hell's bells, all the metric STANDARDS, the KILO things in all them vaults around the world are varying as to true weight.

Why would you doubt that glass can flow at room temperature?


Steel beams will sag over time. Gravity Does do that.


There are now around 20 different phases of matter, depending on who you ask and how you want define them. "Glass" is one of those. So to answer the question "liquid versus solid," you need only reply "It's a glass." It's neither solid, nor liquid. Why would you try to pigeonhole it into one or the other? Obviously, liquid, gas, and solid are no longer adequate to describe the physical state of condensed material around us, and it has been expanded accordingly. However, it would confuse the living daylights out of the casual observer, so schools still teach the "old" model. There's very little to be gained in the sixth grade classroom by diving into quantum mechanics.

Another prime example:

Is plasma a gas? No, it's a plasma.

Further down the rabbit hole (and as some people pointed out), even trying to classify everything people agree as solid can be a bear. Different compounds and materials solidify for different reasons. Are they the same? Waxes solidify under a different phenomenon than say, tungsten does, and hence have wildly different melting points. Are they both truly solids?
Repeat after me:


Lots of politics and plain un-truths in wiki entries.

Plus, if the *really* smart glass people don't read it and bother to update it, all you have is a random gathering of facts that look 'smart' but may be no more accurate than any other random gathering of facts on a web page.
Steel beams will sag over time. Gravity Does do that.

Here we get into an even more interesting concept: creep. Does this make steel more of a "liquid" than glass? I haven't known glass to take a bend under any type of loading at standard temperatures. Provided it doesn't break, of course, but plastics and metals like aluminum will creep and sag and droop permanently if given the right conditions, and AFAIK glass does not do this. So is steel a liquid?

I think it's all semantics past a certain point. And you're right about pigeonholing these things; there really isn't any upside in gray areas unless trying to generalize, in which case surely everyone here would consider glass a solid for the purposes of designing parts.
its a material, it has its own properties, it dosent matter if you want to call it amorphus or supercooled solid solution or a badger it wont care,
i wonder if murcury is a metal or not, it seems to flow at room temperature?
lead flows as does steel and copper i am told [creep? or somthing even more sinister] cast iron cant seem to make its mind up.
Wikipedia ISN'T the ONLY source saying galss is an AMORPHOUS SOLID!

There are TONS of articles and other things I've seen stating glass is an amorphous solid, the wikipedia article is just the first thing that popped up on google that had a reasonable explanation I found. Glass DOES FLOW at ROOM TEMPERATURE, the question is how fast. It's fairly obvious that different formulas of glass will have different viscosities, and diffrent temperature/viscosity properties. Having seen glass that OBVIOUSLY SAGGED under the force of gravity that was kept INDOORS for it's ENTIRE EXISTANCE (over 200 years), I don't beleive its not possible to perceive the "flow" of glass over time. I dunno, I can't POSSIBLY see windows that looked like the ones in our old house being used.
... Is glass a liquid at room temperature? Is it really just an urban legend?

Thanks! :cheers:

proFeign has placed an insidious trap for us. We think we have leaped from a paradigm but we are hopelessly trapped as if held by chains. The problem lies in the definitions he has given us. For instance, “Glass”. This term includes so many different compounds with so widely varied properties, that this alone makes it impossible to answer the question. Then there is the term “Liquid”. I think we are trying to compare these “glasses”, to the familiar and common (and often lethal) single substance called Dihydrogen Monoxide. This chemical compound made of two gases at room temperature, forms a liquid. The same liquid that takes the lives of several visitors to Panama City every year. Thus the paradigm.
The problem is trying to use the terms taught us in school, created by our ancestors; they are too limiting here. I think the ancestors' intent was to be descriptive of pure elements and that the elements are either gas, liquid, or solids, depending on temperature. Can we really apply these terms to these compounds in this case? I think not.

However if you take a bowl and lay it under a large sheet of tempered glass, then whack the glass with a hammer. It will “rain” down in to a shower of small cube-bits that fill the bowl to overflowing, thus proving that glass is indeed a liquid, by definition! :willy_nilly: Joe

Safety Warning: Dihydrogen Monoxide (DHMO)
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Sidestepping the trap of the numerous formulae for glass;

Some glasses (i couldn't tell you the compositions because i don't know) are notably resistant to creep. Much more so than metals, hence their use for the springs in micro gravity meters.

Some (i'm not risking saying all) silicate glasses have signifficant polymerization, even when "molten" due to linking of the SiO4 tetrahedra into chains.

as a parting question:
Is the creep prone steel used for the springs in saggy old Japanese cars more of a liquid than glass at room temperature?:D


Steel beams will sag over time. Gravity Does do that.



Understood, but drive a nail in a wall and a hundred+ years later, barring someone/thing hitting it, it's as straight as the day it was driven. And a nail, compared to a bit of window glass is extremely flexible.

ANd while slamming your fist into things, explore "thixotropic" fluids. Those
are fluids with non-linear viscosities.

For example, mix up a paste of corn starch and water, in a bowl big enought to
slam your fist into.

The stuff pours just fine - but when it is sheared hard, it becomes a solid.

Jim A good example of a non newtonian fluid though it is shear dilatant not thixotropic.

Thixotropic fluids are solid at low shear rates but liquid at higher shear rates, a good property if you want to paint a ceiling
I still want to know if anyone has a documented case of window glass "creep" in which the glass has thickened or slumped at the junction with the frame or mullion, and is thinner in the groove again. People keep saying that windows get thicker at the bottom, but why would they get thicker in the groove too? Even if you allow for the possibility that the pane would expand on the putty side only, a pane retained by points should show indentations there, however slight. If a pane of glass thickens visibly in, say, 200 years, it ought to thicken at least a little bit measurably in 50. If I've missed this, I hope someone corrects me, and I'll gladly accept the evidence, but where are the pictures of window panes that have spread around their frames or their points?
The reason that you won't find any pictures of windows having flowed over or around their frames is a simple one. There aren't any. Someone stated earlier that this is far from a controversial subject among ceramists, and I can attest to that. I am currently working on my PhD in ceramic engineering. As such I often spend time looking into published literature for one thing or another. I've looked for articles which speak to glass flowing at room temperature, and without fail all of them conclude that it doesn't happen. Look, in a setting like this very few of the contributors actually know one another and I doubt anyone here knows me beyond what I have posted, so I don't expect people to just take my word for it. I will ask this though. If you need to know how a specific machining operation is done who do you ask? A machinist. If you want to know how to weld something, who do you ask? A welder. If you want to know how to wire something, who do you ask? An electrician. Well, who do you ask if you want to know about glass? A ceramist. There aren't too many things that I would claim to know better than the average guy, but ceramics and glasses are what I do.
Thank you Mr Watts. Whenever I hear a guy muse about wanting people in public office to be comfortable to have a beer with, I think: what an idiot. Whould you use the same criteria to select a dentist or a surgeon? A Chairman of Joint Chiefs of Staff or a plumber? No. You select for competence and ability to perform whether the guy is genial or abrasive.

You guys whith nothing more than unsupported anecdotes to offer have to yield to knowledgeable authority whether you like it on not. This thread has gone on far too long and assertion of non-adult opinion allowed far too much influence.

Tapered glass is a manufacturing artifact. Craftmen of 400 years ago would naturally install the thick edge down for the sake of the appearance of a scene seen through the panes. Now that I think about it. I wouldn't be surprized if the individual panes were not mixed and matched for the best consistency of view; a giant very low diopter fresnel lens if you will. If the glass was randomly installed horizontal lines would be offset up and down from pane to pane. What was once a consideration for routine craftsmanship has become a cult obsessed with an interesting but unsupportable legend.

In such cases obsession and clamorous persistence with mistaken conclusion is pitted against quietly stated competent authority based on fact and objective evidence. There is an apt aphorism: you can lead a horse to water but you can't make him drink.
Kudos to you sir. Most folk don't even know what a
"ceramist" is! I only know this because I worked with
a lady (paulette onoroto) for several years who did
exactly that job. She studied glass - for GTE labs, and
they were interested in glass research for obvious reasons,
revolving around lamp manufacture.

Her comment - a quiet chuckle, and a smile. "That's
an old story" and then the explaination that yes, glass
is an amorphous solid but the viscosity of cold glass
is simply too large to explain the "old window pane"

It was amazing to see them do sample melts. Silver
suits, furnaces that when you opened up the door,
the whole room lit up. Took fifteen seconds to do the
pour, but you were drenched in sweat at the end of that

Platinum crucibles with platinum stirring paddles, great

Nice little wine bottle, 1700 years old:


No evidence of droop, and it still contains the original wine, preserved with a layer of olive oil on top. A little more force than if empty, for much longer than cathedral windows.

But something else baffles me, and it has not been explained.

On the voting ballot for this thread, one of the choices is bottles of beer in the fridge.

Why is this not a landslide?
There is an apt aphorism: you can lead a horse to water but you can't make him drink.

There are two guys who think there is a way to "make" a horse drink. The first guy holds the horse's head in the water and the second guy sticks a Shop Vac up the horse's butt. Didn't work the first try but as soon as the second guy gets out of the hospital they are going to try again! ;)