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Melting point[edit]

I was searching for the "melting point of glass" found this Wikipedia entry about Glass, but I don't appear to be able to find the actual melting point listed? I realise that the melting point will vary for different "alloys" if that's the correct term, thought it might be something useful that can be added. Name of Tony Hine, published on the 7th of August, 2012 — Preceding unsigned comment added by TØnyHine (talkcontribs) 21:14, 7 August 2012‎ (UTC)

The term "alloy" is typically applied only to metals, although metallic glasses do exist. The thing all glasses have in common is that there is no specific melting point. Rather, there is a "melting range," called the glass transition. Typically, the glass will soften as it is heated through this range between solid and a fully melted liquid. For lead glass, full melting usually occurs around 1600 degrees F, which is a glowing cherry-red color. Quartz (Fused silica) has an extremely high melting poiny of around 3000 degrees F (a "crisp your eyeballs" white-hot). Quartz also has a rather narrow glass transition, turning from solid to liquid with very little warning. Zaereth (talk) 05:20, 20 March 2013 (UTC)
From a practical (glassblower's) standpoint, melting is usually deemed to have occurred when the surface tension lowers to the point where welding can readily take place. Zaereth (talk) 18:35, 20 March 2013 (UTC)

Proofing of "state" Section[edit]

The "state" section of the article needs proofing. There is incorrect grammar. I would have made the changes but I was not allowed to see that section while in "edit" mode. — Preceding unsigned comment added by (talk) 15:31, 5 October 2012 (UTC)

I'd be happy to help, but I don't see any section titled "state" in the article. Can you provide a little more description of what needs to be changed and where? Zaereth (talk) 16:26, 5 October 2012 (UTC)
Oh, I see. It looks like Polyamorph already fixed the problem. Zaereth (talk) 19:30, 5 October 2012 (UTC)

Behavior of antique glass[edit]

How should this section be reworked since the statement "...once solidified, glass does not flow anymore." is at odds with results found in the paper "Relaxation time and viscosity of fused silica glass at room temperature" by M. Vannonia, A. Sordini, and G. Molesini in the European Journal of Physics E Volume 34, 2011? Dan Watts (talk) 14:48, 12 April 2013 (UTC)

I don't know, so I will have to defer to others, because I do not have access to the full paper. I was able to locate the first two pages, here. From what I have read, there doesn't seem to be any cause attributed to the deformation. What we have here is a detailed analysis of a pair of optical flats that were purchased in 1981, which were rarely used, but were found to be off by a few nanometers in 2008. They equate the deformation to viscous flow, but don't actually say viscous flow is the culprit. In fact, to quote, "Although still on a dubitative ground as to the causes of the observed behaviors, cases of long-term defomation of fused silica plates at room temperature have been reported."
To me, this is an example of why extreme caution should be taken when using primary sources. A good, reliable, secondary source can often provide a much better interpretation. The problems I see with this one (albeit, I haven't read the whole thing ... I think) are: 1) The article reports this as an unexplained deformation. 2) The flats were only tested between 2008 and 2010, during which time there was "no appreciable change." However, during this time, they noticed that there seemed to be a deviation from the original flatness. 3) There is no way to actually know what the true (absolute) flatness originally was, because they were not originally subjected to the three-flat test. They may have been off the whole time, because flatness of the sample flat in an interferometer test is usually relative to the flatness of the test flat 4) This is a very small case study (only two flats, one type of glass, over a two year period, with no change during that time).
I would definitely not try to use this as definitive proof, because it is an admittedly incomplete study. Zaereth (talk) 22:26, 12 April 2013 (UTC)

I appreciate your response, and delving into the references (including one that did observe masurable deviation and is available { } ) it appears that the first paper is not the best one to use. Perhaps you could also look at this one. Dan Watts (talk) 01:42, 14 April 2013 (UTC)
No problem. This report is similar, except the study is more detailed. This is a study of five flats, of which, only two actually showd any deformation. With one flat, the deformation was rather uniform, similar to the other report's. The other flat showed deformation only in the center, as if the properties of the fused silica varied across the flat. The other three flats showed no deformation during the test period. The report also claims the cause as unknown and, what's more, they have no idea why some flats deform while others do not, and still others only partially deform.
I'm beginning to think this info would best be suited to the fused silica article, but definitely not for antique glass. The optical flat article could definitely use more information. While the report equates the deformation in the fused silica to a viscosity of 1017 Pa s, it still lists soda-lime glass as being around 1041 Pa s. Significantly higher.
These studies show that deformation does occur in fused silica in a way that it does not in other glasses. Further more, it also shows that such deformation is not universal, but sporadic, indicating some possible deviation of the material's make-up. When including this info into an article, I would be careful to explain all of this, to state that the deviations are on the order of a few nanometers, and the conclusion is that "no observable effect is ocurring over human lifetime." Zaereth (talk) 17:19, 15 April 2013 (UTC)
Perhaps the conclusion should be "no unaided observable effect is ocurring over human lifetime." They did measure an effect for two flats. Dan Watts (talk) 18:43, 15 April 2013 (UTC)
I can agree with that, and almost added a similar adjectives to the quote, but I would've had to put it in brackets to avoid misquoting. Zaereth (talk) 18:56, 15 April 2013 (UTC)


Could we get more-definitive dates in antiquity? and a clearer outline, chronologically, in the History section? Thanks! Now to look for more info about window glass. Misty MH (talk) 08:39, 25 July 2013 (UTC)

English spellings[edit]

It appears this article was started using American English in 2001, and then was switched by an IP user in 2006 to British English, for no apparent reason. I will be switching it back as time allows. — Preceding unsigned comment added by (talk) 15:46, 22 August 2014 (UTC)

I've reverted you - we have to keep spelling in references; and if correcting, change spelling all through the article. I'll try to correct this today. Materialscientist (talk) 21:52, 22 August 2014 (UTC)