Talk:Glass/Archive 5

Lead
The lead of this article doesn't appear to me to be very clearly worded. Is it defining glass as the familiar substance found in windows etc., or all substances capable of a glass transition? The first few sentences seem to define glass in a broad sense, then later it states "In science, the term glass is defined in a broader sense, encompassing every solid that possesses a non-crystalline (i.e. amorphous) structure and exhibits a glass transition when heated towards the liquid state" - yet this is what was stated at the beginning, is it not? It also refers to "silicate glass" without explaining what that is - is it the same as the previously mentioned soda-lime glass? PaleCloudedWhite (talk) 08:54, 4 November 2014 (UTC)


 * The answer is both. In a general sense, as understood by most people, "glass" refers to silicate glass, which is glass that is made primarily from silica. This can be either pure, fused-silica, or it may have other additives like lime, boron, lead, or iron to change its color and melting temperature. Silicate glasses are what most people think of when they hear the term "glass." This definition is more general, but also more specific, because it is referring to a very specific type of material.


 * In the scientific sense, the meaning is more specialized, yet has a broader coverage of materials. This includes things like porcelain and plastic, which a general audience usually doesn't think of as being glass. However, when, say... welding glass, it behaves very similar to welding plastic.


 * The purpose of the lede is to have a very general summary of the entire article. The first sentence should define the term in its broadest sense, and then more general and specialized definitions should follow. I do think you're right, that silicate glass should be defined, and perhaps the wording could be clearer, but the term glass is used to cover all these definitions, so that needs to be covered in the lede. I'll look into this further when I get more time. Zaereth (talk) 17:22, 4 November 2014 (UTC)


 * Thanks for replying. I would have been bold and made some adjustments myself, were it not for my lack of knowledge. I imagine the defining of silicate glass could be done fairly simply. The other matter - of wording - perhaps requires more input. I'm trying to understand the difference between the broad yet specialised scientific definition and the definition "in its broadest sense", because at the moment the lead seems to imply they are the same. Would it be technically correct to state, as the first sentence, "Glass is any amorphous solid (non-crystalline) material that exhibits a glass transition", rather than "Glass is an amorphous solid (non-crystalline) material that exhibits a glass transition"? PaleCloudedWhite (talk) 21:15, 4 November 2014 (UTC)


 * Thank you. It's a lot easier to spot problems after someone points them out, so your comments are very helpful.


 * That seems like an OK solution for the time being. You may also want to fix the last sentence of that paragraph, changing "this" into "silicate glass" (in quotes) and then add a brief definition of the jargon.


 * I see many other problems, especially with that first sentence, which I find to be an extremely circular definition. It's like saying, "Metal is a metallic substance that displays the qualities and properties of a metal." We can't define glass a simply being amorphous and having a glass transition, without confusing the hell out of any newcomers to the field and its jargon. Unfortunately, I am at work, and only have time when I am on hold or whatever, so it may have to wait a while for me to give this the attention it needs. In the meantime, you are more than welcome to make the change you suggested, or anything else that helps improve the article. Zaereth (talk) 21:37, 4 November 2014 (UTC)


 * Thanks. I've changed the first sentence as proposed. I'm still not sure if "silicate glass" is the same as "soda-lime glass", so haven't altered anything else as yet. This is a new topic for me. I agree the first sentence is generally confusing - I wonder if it's possible to write a definition which doesn't necessitate readers having to follow links before they understand what's being said? I shall also give this more thought, albeit tomorrow - because while it's worktime in Alaska, it's bedtime here in London... PaleCloudedWhite (talk) 22:14, 4 November 2014 (UTC)


 * Yes, soda-lime glass is a form of silicate glass, and is most commonly used for windows. It also includes lead glass, borosilicate glass, quartz glass (fused silica), pyrex, etc... It also includes various stained glasses, which have metal additives to color the glass. Neodymium colors it purple (and is also good for laser material), chromium colors it green, and uranium pink. A typical, green beer or wine bottle is likely colored with iron. All of these glasses have silica as the prime ingredient. Zaereth (talk) 00:17, 5 November 2014 (UTC)
 * Okay, present lede is now in nested form suggested above. Let me know if it's still confusing. S  B Harris 00:56, 5 November 2014 (UTC)
 * Hi Sbharris. It does look a lot better to me. (I meant no offense it you are the author of the sentence.) The thing I always try to consider is that the first sentence will be read by everybody, and that includes small school-children. In fact, the average elementary-school child will probably only read the first sentence and never go any farther. Very rarely will they venture past the lede, so I try to keep that in mind when wordsmithing that first sentence.


 * I try to think of it like this: The first sentence should define the entire subject in the fewest, simplest words possible. So the question to answer is, what is a glass and how is that different in comparison to other materials. (Sorry, just thinking outloud here.) So what are the properties of a glass? How about: "Glass is a solid material that has no specific melting temperature and no microscopic crystals that make up its structure. This lack of crystal structure is referred to as "amorphous" (non-crystalline). A glass is a material that exhibits a glass transition, which is the reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle state into a molten or plastic state...." Or something like that. How does that sound?


 * Also, I would drop the phrase "as noted above" because it not only is unnecessary, but it also turns the writing into second-person. Zaereth (talk) 02:21, 5 November 2014 (UTC)


 * Saying in the lead that a glass doesn't have a melting point is opening up a can of worms and I've removed it. I think the first sentence that states a glass is an amorphous (non-crystalline) solid that exhibits a glass transition is a good enough summary,  I don't feel it is necessary to describe the detailed characteristics of the glass transition in the lead, since we wikilink to its specific article. Polyamorph (talk) 10:57, 5 November 2014 (UTC)
 * Possibly, instead of trying to describe the glass transition, we could just add a sentence following the first sentence e.g. "glasses are typically formed by supercooling the melt, forming a supercooled liquid which solidifies at the glass transition." That provides a wikilink to the reader to supercooling and supercooled liquid and is less confusing to the general reader, possibly! Polyamorph (talk) 11:05, 5 November 2014 (UTC)
 * Done. Polyamorph (talk) 11:16, 5 November 2014 (UTC)
 * Hi Polyamorph. Long time no see. Well, I guess I'm just old-school, because I've been doing this long before wikilinks or even the internet was invented. My personal view is that the lede should never need a wikilink for people to understand what it's talking about. Imagine coming to this article for the sole purpose of finding out what the heck this term "glass' means, and having to read three other articles just to understand what the very first sentence means. That's pretty discouraging and is more likely to deter people from reading any further.


 * When writing the first sentence, I always try to think of it like this: How can I define the entire subject in a single sentence, with as few words as possible, and have it be able to stand on its own without any help from other articles. Imagine you need to define "glass' for a class of elementary-school children, and one sentence is all you get. No wikilinks. No other information to help you, but all you have is one sentence to give these kids the best understanding of the subject that you can muster. As I see it, that is the challenge. Zaereth (talk) 18:12, 5 November 2014 (UTC)
 * I get your point, but the lead is supposed to summarise what is in the article. So a full explanation in the lead is not necessary, just a summary of the key concepts as all can be explained in more detail in the article. Since this article deals with glass in the general sense, and not just the state of matter, i dont feel we should over emphasise the physics in the lead. I felt that as it stood the summary was overly confusing. but that's my opinion. I also removed some repetition.  Polyamorph (talk) 22:56, 5 November 2014 (UTC)

I don't think it's very helpful to say that a glass is something that undergoes a "glass transition" and leave that as a link with no explanation. That's like saying that morphine induces sleep by means of its dormative or narcotic properties. Or that an anesthetic is anything that produces a state of anesthesia. And talk about opening up a can of worms-- why introduce the concept of "supercooling," and "quenching" especially when you don't need it? Glasses are traditionally formed by rapid quenching and undercooling of a liquid, forming a supercooled liquid which solidifies at its glass transition temperature This isn't even TRUE. Window and bottle glass don't need rapid quenching, and any rapidity in the process is only to increase throughput in manufacture. Typically, silicate glasses can be vitrified and devitrified at will without fear of crystalization, and with any speed you like (if you've watched a glassblower work). So the sentence above makes an explanation and leaves an impression that is simply false for the most common type of glass the reader will have any experience with! S B Harris 23:40, 5 November 2014 (UTC)


 * I didn't say it was perfect. Supercooling is certainly needed, I agree with you about the rapid quenching part though so have removed that.  As Zaereth said, we need a simple introduction of what a glass actually is.  I believe what we had before was confusing.  It may well still be confusing.  But lets fix that.  I also don't understand the adversity to wikilinks.  We can't go defining every single term whenever it arises.  Wikilinks are part of the beauty of wikipedia.  But Zaereth is right.  The question is how do we go about it? Polyamorph (talk) 10:03, 6 November 2014 (UTC)


 * The first sentence currently reads "Glass is any amorphous (non-crystalline) solid material that is capable of going from a hard to a more fluid state with increased temperature, without changing phase". This is still misleading, because as a glass is heated through Tg it undergoes a continuous phase change to a supercooled liquid.  So as it stands, the lead is inaccurate.  I'm not sure this is the best way to define, to a lay reader, what glass really is.Polyamorph (talk) 12:05, 6 November 2014 (UTC)


 * Personally, I think we need a much more general definition as the first sentence, keeping "Glass is an amorphous (non-crystalline) solid" but continuing with something along the lines of how it has widespread practical, technological and decorative usages. Then leave any of the science discussion regarding Tg, its formation and viscous behaviour to the final "science" paragraph of the lead.Polyamorph (talk) 12:16, 6 November 2014 (UTC)


 * Thanks everybody. Sorry I didn't respond sooner, but I've been terribly sick for the last week. (Still not over it.) I think that opening sentence does look a lot better as a nice, simple introduction to the subject, and the lede overall has better flow and cohesion. Thanks for your assistance with this, everyone. It's really nice to participate in some good collaboration like this. Zaereth (talk) 18:09, 10 November 2014 (UTC)

Lead revisited
I'm going to start this topic again. The definition of glass in the first lead paragraph is still unclear and circular. Definitions must be invertible. If you say, glass is such-and-such with the properties of so-and-so then everything that is such-and-such with properties of so-and-so must be glass without exceptions.

It is perfectly OK if your definition has a little wiggle room but only if the term itself applies to different referents. But if you give two definitions of glass, let's say "glass in common usage" and "scientific glass" and I give you any object, you must be able to say, according to the two definitions, that (1) the object is or is not "common glass" and that (2) the object is or is not "scientific glass". For example, does quartz meet the definition of glass? Does flint?

The 1913 Webster defines glass as "A hard, brittle, translucent, and commonly transparent substance, white or colored, having a conchoidal fracture, and made by fusing together sand or silica with lime, potash, soda, or lead oxide." Obviously, this must be brought up to date but are the words brittle, translucent, conchoidal fracture and fused sand or silica plus amorphous solid enough to make up the definition of glass? --RoyGoldsmith (talk) 19:13, 30 September 2015 (UTC)
 * Here's the thing. The 1913 definition is adequate for silicate glass. However, due to scientific advancements, the term in a scientific context now refers to much more than silicate glass. In fact, although some materials form a glass more readily, just about anything can become a glass if it is cooled sufficiently fast and low enough to produce a glass transition without crystallizing first. Water can become a glass. (If you're ever cryogenically frozen, you'll want to do it fast, so that all that water in your body doesn't crystallize and rupture the cells.) So can sugar. (Many hard candies like peanut brittle, suckers or Jolly Ranchers are in fact glasses.) Metals can become glass, but the cooling rate needs to be extremely fast. Quartz only becomes a glass if the cooling rate is quick enough, or else you end up with crystal quartz, which is not as transparent. (Fortunately, in quartz and other glass formers, this rate is quite long.) Flint? Probably, if the same conditions are met. Now, the language has changed, as languages often do, but the general population has not yet caught up to the science, so we have these two seemingly-conflicting definitions to deal with. The challenge is to bring both of these definitions together and show that one is merely an extension of the other, and not really different at all, but that is nearly impossible to do in a single sentence, or even a single paragraph. Therefore, in my opinion, it is best to start with the general definition, and then explain how that relates to the scientific one, similar to the way SBHarris has already laid it out. Zaereth (talk) 20:31, 30 September 2015 (UTC)
 * I think the current definition is fine. Glass is an object in everyday use and in general that glass is silica based.  However, scientifically we have many forms of amorphous materials which may be classified as glass.  We described both definitions and I don't see any issue. Polyamorph (talk) 09:02, 1 October 2015 (UTC)
 * You know, on a side note, I find this a lot in many articles where the language changes in one context yet not in another, which leaves us the task of sorting out the confusion without attempting to change the language. For example, certain people constantly want to change the alloy wheel article to include steel wheels, or who come to the alloy steel article complaining that steel is also an alloy. A hundred years ago, steel wasn't considered an alloy, because at the time "alloy" referred to a mixture of metals. It is fairly recent that "alloy" came to include metals mixed with non-metals, yet the language is still full of these conflicting terms to sort out. (Be glad you're not working on a dictionary.) Zaereth (talk) 18:02, 1 October 2015 (UTC)
 * Polyamorph, you may be right. Can you think of a common "amorphous (non-crystalline) solid" (the current definition in the article) which is not glass? Can we say that translucency (not necessarily transparency) is a necessary condition for glass, including 99% of modern glass? This is not a high-school geometry class -- one case in some obscure field of technology does not invalidate a definition. After all, the developers of that so-called "glass" may by wrong in using the term glass. Does glass need to be brittle, using the 99% rule? Does it need to be solid?
 * Toffee? Translucency to what wavelength? Black glass is a thing we recognise as glass. Opal glass also. Should we exclude obsidian?  Plant surfer  18:22, 2 October 2015 (UTC)
 * you talked about a "glass transition without crystallizing first". The lead paragraph in the article Glass transition contains the statement: An amorphous solid that exhibits a glass transition is called a glass. Couldn't this be used in our article:
 * Glass is an amorphous solid that has undergone a glass transition; that is, has exhibited the transition from molten or rubber-like liquid to a hard and relatively brittle solid without crystalizing. Glass is often transparent and has widespread practical, technological, and decorative usage in things like window panes, tableware, and optoelectronics. ...
 * Can you think of a glass that has not undergone a glass transition? To reverse, can you think of any solid which has undergone a glass transition but which you would not classify as glass? --RoyGoldsmith (talk) 17:56, 2 October 2015 (UTC)
 * Glass is not rubber-like in any respect Michelin would recognise. When molten it is more like molasses, or toffee. It does not stretch and rebound.It does not compress and rebound. We probably won't be seeing glass bands or tyres any time soon.  Plant surfer  18:22, 2 October 2015 (UTC)
 * See, this is the type of confusion that needs to be sorted out. I would estimate a good 90% of people coming here (and I'm being conservative) are simply looking for the definition of the glass that we scientifically term "silicate glass." Most of the people who come to an article aren't going to read the whole thing, they just want the question "What is glass" answered in as few words as possible. Those who come for the broader definition are much fewer and likely will read the entire lede at the very least.


 * Transparent glass is what we are most familiar with, but, scientifically, glass does not necessarily need to be transparent or translucent at all. Porcelain certainly is not, and that is for just about all wavelengths. (Quartz is only transmissive from ~ 170 nm to 3000 nm. Other silicate glasses are even less.) Metallic glasses are not. They do not necessarily need to be brittle. Teflon is not brittle at all. They may in fact be rubbery when molten, like PVC, but this is not a necessity. I'd defer to Polyamorph on this as the local expert, but the two condition that must be met is that they are amorphous and that they exist below their glass transition. Toffy, honey, or corn syrup are not glasses at room temperature; they are glass formers. Drop the temperature enough they become glass. (For honey that's around -60 degrees F.) Zaereth (talk) 18:55, 2 October 2015 (UTC)

BINGO, Zaereth. The problem isn't really with the lede at all, but the fact that it's being tasked with summarizing an overlarge article. Our underlying problem is with the dab, the directs, and the fact that we now have a bloated article ready for mitosis. What we really need, is an article split:

[1] One article called Silicate glass (not a redlink now, because it redirects to glass, instead of a redirect that should be the other way around!),

[2] Another called Glass types and uses (which would have a small section on silicate glass, with this as as a main article, but focus mostly on all the other types of glass)

[3] And finally one called Glass (physical state), which discusses the physics of glass as a state of matter.

Just about everything in this monster article can be divvied up into these three, with a few synopses per WP:SS for things in one article that need to be summarized in one or both of the other two. The subarticles in this article can be similarly divvied up. Finally, when somebody enters "glass" in the search box, it can redirect to Silicate glass with a note to look at the other two articles for other types of glass and for information about the glass physical state. S B Harris 22:33, 2 October 2015 (UTC)


 * I agree with that. Looks like a gargantuan task, though. I can help, but may not have much time until winter fully sets in. (Then I'll have lots of time.) The thing I would want to avoid is circular reasoning, which (no offense to anybody in particular and certainly not on this article) is all too common in both scientific and technical media, of all kinds. You ask, what is energy? "Well it's mass." What is mass? "Well it's energy, dont'cha know? Mass and energy are equal." Try to find out what wattage is. "Volts times amps." Well then what is voltage? "Watts divided by amps." If you're a beginner to the subject, tis gets frustrating quick.


 * From the original complaint that started this all, we had an opening statement that was basically, "Glass is an amorphous solid that experiences a glass transition when heated. So you go to the glass transition article, and it says "he transition from a hard into a molten state." So it's synonymous with melting? (Of course not, but you have to dig really deep to find that out.) Then go to the amorphous article, and it says a solid without any long-range order. None of this tell me, the complete novice/beginner, what any of these terms actually mean.


 * In the welding article, I simply referred to the glass transition as a temperature range. It is much more than this, for sure, but for welding glass, all you really need to know is that it doesn't have a specific melting point, and to me that's the one key thing that really stands out. The real challenge, I think, is to define these terms as precisely, concisely, and as quickly as possible so that the reader can get the gist of what we're talking about right away. Without some context provided early on, none of the following information will make sense. Zaereth (talk) 02:29, 3 October 2015 (UTC)


 * I took some time over the weekend, reading a few books and trying to come up with a single sentence that explains what amorphous and glass transition mean. Even this book, Assignment of the Glass Transition, Issue 1249, although it goes into some depth on giving an "operational definition," it doesn't give a clear definition early on. Instead, it begins with an opening sentences by making a distinction between it and the other transition: "The glass transition is one of two transitions that characterize the change from a solid to a liquid; the other being the melting transition." While this is extremely vague, it does provide an idea of what it both is and is not. I think something similar could be used for the opening line of the glass transition article.


 * (Interestingly, the book also touches on the language problem I've mentioned: "Our language was created long before the scientific principles of many of the phenomena to be described had been understood, and changes in the meaning of a once established word, based on scientific evidence, are hardly ever possible.")


 * For this article (or an article on glass, the physical state), I think we should first vaguely define what a glass is before defining what glass itself is. I think it may help to take our original definition and try applying some operational definitions to the jargon. Instead of simply saying, "Glass is an amorphous solid," we could try, "A glass is a solid that has no organized, crystalline structure (amorphous solid), but rather has its atoms or molecules arranged in an overall random pattern. A glass is a phase of matter in which a material enters as it is supercooled below its melting transition and then below its glass transition, which is a radical change in material properties (hardness, ductility, formability) that occurs when a supercooled, viscous liquid becomes a solid. This glass transition typically occurs over a broad temperature range rather than a specific melting point. Instead of forming a neatly ordered, crystal lattice, the thick, viscous liquid slowly grinds to a halt to enter the solid state." Or something like that. The addition of "A" to the sentence lets the reader know we are speaking in general, not specifics.


 * I have to admit, I still don't understand the glass transition at all, which is why I don't meddle with the article very much. In many ways it reminds me of the martensite transformation in crystalline alloys. (I can picture crystallizing like soldiers all wandering aimlessly on a field. When the sergeant yells "A-Ten-Hut!" they all suddenly file into neat little rows. For the glass transition, the sergeant yells "A-Ten-Hut!" and everyone just slows down, but continue wandering aimlessly. Then the sergeant get's frustrated and yells "Stop!" and suddenly everyone stops right where they are.) The specifics and the science of it all are better worked out by people more knowledgeable than I, but I think an opening statement similar to what I've described will help tie it all together, so that it will be easier to understand why the material we call glass is also a glass. After that, the lede as we have it should all come together nicely. Zaereth (talk) 00:44, 6 October 2015 (UTC)


 * Isn't your definition circular as well. You say a glass is [a] a solid that has no organized, crystalline structure [that is, an amorphous solid], but rather [b] has its atoms or molecules arranged in an overall random pattern [another definition of an amorphous solid]. Would it be better to say (for the non-scientific, 99% true definition) "Glass is a solid, hard, brittle, translucent material that is commonly transparent"? Then we could start talking about glass transitions for the formal definition.


 * Let's step back a few steps. First, I'm assuming that the word "transitions" in glass transitions means a phase transition, liquid-to-solid. Right? Second, are we sure that glass transitions is not another circular definition: Anything which undergoes a glass transition is glass and glass is anything that undergoes a glass transition. The lack of a definition in Assignment of the Glass Transition and other places may mean that there is no formal definition of "glass transition": the term simply means any phase transition that results in glass, which is undefined. (I'm not saying this is true, I only mention it as a possibility.)


 * OK, can we define glass negatively? What amorphous solids are NOT glass? Can you think of a general term or terms (as many as you like) for those solids? If so, we might be able to define glass as an amorous solid that is not (that is, does not belong to the category of) A, B or C.


 * I have also left a note on the WikiProject Physics talk page. Maybe a physicist can help. --RoyGoldsmith (talk) 19:04, 10 October 2015 (UTC)


 * A circular definition is one that uses its own word to define itself. It's like saying "Air-combat maneuvering is the art of maneuvering a combat aircraft." (Which the air combat maneuvering article actually said until a few days ago.) "Combat aircraft" is pretty clear to even a child, but "maneuvering" may not be, and certainly both of these terms need to be expanded upon in the very first sentence. It is typically not necessary to define them in great detail in the opening sentence, but rather a few synonyms or a short description of what a combat aircraft does will suffice. The opening sentence will be inherently vague, but should provide an all-encompassing definition of the subject, which provides context for the following information. So the challenge is to come up with a definition that covers all the types of glass covered in the article, which limits the definition to those two sets of criteria: that it is amorphous and that it exists below its glass transition. As mentioned above, transparency, translucency, brittleness, etc., are not all-encompassing definitions.


 * "Amorphous" is actually pretty simple to define, and expanding on that definition is not circular. Any 6th grade student should be expected to have a vague understanding of what atoms are, so I don't think it unreasonable to add some clarification of what "amorphous" means. My main point is that the three definitions should be listed here, in the very first sentence, because the reader should be able to read the entire article, and be able to infer all meanings directly from context, before they ever need to click on a wikilink. (See User:Zaereth/Writing tips for the amateur writer for more info.)


 * The big hang-up is the term "glass transition." That should be defined here, in this article, as quickly as possible. Unfortunately, as per the book I mentioned, this is very difficult to do in a single sentence, or even an entire book. However, you have to start somewhere, which leaves us the task of trying to create a vague understanding that will leave the 6th grader satisfied that they've learned something. Keep in mind that I'm only talking about the opening statement. This should, technically, be a single sentence, but in this case, may need to be a small paragraph. There is plenty of space to elaborate in the following sentences.


 * Once again, your definition is adequate for silicate glass. I agree with SBHarris that this article should be split, and yours would be a great opening sentence for the silicate glass article. Something like I described would be better for an article about glass (the physical state). However, as this article sits now, the opening statement should be all-encompassing, and many of the properties you've listed just are not. Zaereth (talk) 21:31, 10 October 2015 (UTC)


 * I'm confused. Could you provide me with some examples of NON-silicate glass, especially examples that would be recognizable, as a form of glass to layman readers? Also, what makes them NON-silicate glass? (I would say that they don't have any silicon. Or much silicon. But what do I know?) --RoyGoldsmith (talk) 20:00, 11 October 2015 (UTC)


 * A "glass" (in the physical sense) is a substance with no crystalline order that doesn't go through a phase change to become a solid. It just gets stiffer and stiffer as it cools, and finally hardens to a solid. A good example is whatever polymer your plastic eyeglass lenses are made of. Polycarbonate, etc. That's a non-silicate glass, a thermoplastic. You can melt it and harden it again as many times as you like. Think of acrylic glass or "Plexiglas". The plastics our manufactured world is increasingly made of, are thermosetting polymer glasses, from small item packaging to car bumpers. Of course, not all transparent. S  B Harris 02:30, 14 October 2015 (UTC)


 * Exactly. As a physical state, a glass is one of two solid-states of matter; the other being crystalline solids. When a liquid is cooled, it eventually reaches its freezing point (melting point). At the freezing point, it crystallizes. Some materials, such as iron or copper, crystallize extremely fast, while others, like silica (sand) or honey, take a long time to crystallize. If the liquid is cooled past the freezing point before it has a chance to crystallize, it becomes a "supercooled" liquid. For example, honey's freezing point is 120 degrees F, so at room temperature, honey is a supercooled liquid. If given enough time, the honey will crystallize.


 * A supercooled liquid gets thick and sticky, very similar to honey in texture. (Most adhesives are supercooled liquids, which is why most tapes lose their stickiness in cold weather.) If a "seed crystal" is added, it will begin to crystallize, sometimes rather rapidly. A simple example of this is often seen in beer. If a beer is placed in a freezer for too long, it will generally become supercooled before it freezes. If you open it and take a drink, you'll notice that it is much thicker than water. Since it's far below the freezing point of water, it may freeze some of your saliva, and these seed crystals cause the beer to crystallize right before your eyes, generally within seconds.


 * If a supercooled liquid is cooled far enough, it reaches something called the "glass-transition temperature." Instead of a single temperature, this actually consists of a temperature range. As the supercooled liquid gets colder, it gets thicker and thicker, until the honey-like liquid is more taffy-like. At the glass transition, it begins to lose its sticky surface and starts to act more like a formable solid (plastic) than a liquid. Throughout the transition, the properties change dramatically, becoming more and more like a solid and less like a liquid. Below the glass transition, it behaves only as a solid.


 * Any material that can be melted or frozen can (theoretically) become a glass. Water, metals, beer, sugar, you name it, and it has the potential to be a glass if cooled under the proper conditions.


 * A simple experiment is to make some rock-candy. First you mix about half sugar and half water. All of the sugar won't dissolve, so you have to heat it up. Once dissolved, the liquid is cooled to room temperature, making it a supercooled liquid. Then tie a string to a sugar cube and hang it in the liquid. The seed crystal will cause the liquid to crystallize around it, and you can grow nice, big, white crystals of sugar.


 * Now, do it again, but add some food coloring to the liquid. After making the rock-candy, you'll find that the crystals are still white, because there was no room for the food coloring atoms to fit inside the neatly-ordered crystal. If you want to color the sugar, you have to heat it past its melting point, add some coloring, and then cool it past its glass transition to form your Tootsie-roll pop, or whatever. Cotton candy is made in the exact same way that fiberglass is made. Many, many of the common things we use everyday are physically glasses, but silicate glass (silica glass, or glass made from sand) was the original and is still the most familiar. Zaereth (talk) 07:58, 14 October 2015 (UTC)

The following is from the lead paragraph of Amorphous solid:
 * In some older books, the term has been used synonymously with glass. Nowadays, "amorphous solid" is considered to be the overarching concept, and glass the more special case: A glass is an amorphous solid that exhibits a glass transition. Polymers are often amorphous. Other types of amorphous solids include gels, thin films, and nanostructured materials such as glass.

This definition calls for three classifications of solids: crystalline, glass and other types of amorphous solids, such as polymers, gels and thin films. Do you agree?

If you do agree then we have a definition: Commonly, glass is any solid, hard, brittle material that is translucent or transparent. Scientifically, glass is any amorphous solid that exhibits a glass transition.

If you don't agree with the amorphous solid article then perhaps your disagreement comes from the phrase "Nowadays, amorphous solid is considered to be the overarching concept and glass the more special case". Do you disagree with that statement? Do you think we ought to change the "amorphous solid" article? --RoyGoldsmith (talk) 22:27, 14 October 2015 (UTC)


 * No, and here is why. Crystal quartz is solid, it's transparent, and brittle, yet it's not a glass. Porcelain (chinaware or toilets) is hard and brittle, yet is not transparent, but it is a glass. Polyethylene (sandwich bags, water bottles) is translucent, but is not hard nor brittle, and yet is still a glass. Spectralon (light reflector) is not hard, brittle or translucent, yet is still a glass. Asphalt (tar) also has none of these properties, but is also a glass. So what do all of these glasses have in common? What are the things that distinguish crystal quartz from quartz glass? Zaereth (talk) 22:56, 14 October 2015 (UTC)

Arbitrary section break

 * The article's lead has changed since I first broached the subject in September. The only thing I would do to it now is to move the "scientific" definition closer to the beginning. Maybe like this:
 * Glass is an amorphous (non-crystalline) solid which is often transparent and has widespread practical, technological, and decorative usage in things like window panes, tableware, and optoelectronics. In science, the term glass is often defined in a broader sense, encompassing every solid that possesses a non-crystalline (i.e. amorphous) atomic-scale structure and that exhibits a glass transition when heated towards the liquid state.
 * The most familiar, and historically the oldest, types of glass...
 * --RoyGoldsmith (talk) 13:29, 16 October 2015 (UTC)


 * That's better, but I still like the idea of explaining what the terms mean in very simple language, because the lede mainly is for the children and newcomers to the subject, or people who just want to know what the heck this term "glass" means (perhaps because they encountered it in another article and want to go back and finish reading it.) Personally, I don't like the idea of relying on wikilinks to define jargon, because it breaks the flow of reading, plus the linked articles may not provide a quick answer either (if at all), sending the reader off on a scavenger hunt for terminological definitions.


 * Perhaps it would be better to start from scratch. The lede really shouldn't be much more than a dictionary definition. Let me ask you this: Let's say we move the lede down into a section called "Introduction." Most technical and scientific articles should have an intro section, which is really just an expanded lede written at a high-school level (For examples, see: Alloy, Tempering (metallurgy), or Basic fighter maneuvers.) If we do this, then we have room for a lede consisting of one to three short paragraphs. Starting from scratch, how do you think we could best summarize all of this in as few words as possible --without the use of wikilinks-- and still make it understandable to the widest possible audience (not just to other scientists), assuming they have absolutely no background knowledge of the subject? Zaereth (talk) 00:04, 17 October 2015 (UTC)


 * Wikipedia articles are not written for young children. I think of the Wikipedia audience as intelligent high-school graduates. The word "glass" (meaning that stuff in windows and Coke bottles that you can see through) is known by virtually all kindergarteners, who can't read and are therefore not candidates for Wikipedia readership.


 * I think you're confusing a newspaper lede from a Wikipedia lead. See Manual of Style/Lead section. WP leads are substantially longer than news ledes and should be a summary of every important section of the article, not just a definition. A summary should be concise but thorough. Leads should therefore include as many wiki-links as feasible, for conciseness. But the lead should contain nothing, except for possibly the definition, that is not restated in the detail below.


 * Nevertheless, I believe that the article's lead is too long. In my opinion, the way to shorten it is to reduce the sentences in each paragraph, rather than reduce the number of paragraphs in the lead. For example, does
 * A very clear and durable quartz glass can be made from pure silica which is very tough and resistant to thermal shock, being able to survive immersion in water while red hot. However, quartz must be heated to well over 3,000 °F (1,650 °C) (white hot) before it begins to melt, and it has a very narrow glass transition, making glassblowing and hot working difficult. In glasses like soda lime, the other compounds are used to lower the melting temperature and improve the temperature workability of the product at a cost in the toughness, thermal stability, and optical transmittance.
 * have to be in the lead or wouldn't it be better positioned somewhere else?


 * Being bold, I've changed the definition in lead paragraph. If you think it would be better the old way, please change it back. --RoyGoldsmith (talk) 19:19, 18 October 2015 (UTC)


 * I don't necessarily follow with Wikipedia's MOS, because it's still in its infancy. To be honest, I've never actually read it too much, because I've been doing this sort of thing since long before there was a Wikipedia. When a subject is very complex, splitting the lede and formatting in the standard pyramid structure is a very common way of delivering information. I don't edit war nor have any intentions of changing your edits. I'm just trying to offer useful suggestions in the spirit of collaboration. Just keep in mind that elementary school children (K--6) are indeed capable of reading, and understanding far more than you're giving them credit for. Wikipedia is for everybody, so there is no need to exclude a particular group. (Glass and metals have always interested me since I was very little. I rebuilt my first small engine at the age of 7, built a crossbow at 10, and forged my first sword at the age of fourteen. I read up on these things, experimented with them, and always hated those articles which condescended to me.) Zaereth (talk) 23:34, 19 October 2015 (UTC)

Lead as a network Former
Lead silicate glasses: Binary network-former glasses with large amounts of free volume

S. Kohara, H. Ohno, M. Takata, T. Usuki, H. Morita, K. Suzuya, J. Akola, and L. Pusztai Phys. Rev. B 82, 134209 – Published 29 October 2010

Shows that PbO can change to be PbO4 or 3 and act as a glass former, with up to 90mol% Pb and no phase separation. Clearly lead is more complicated that just that as a network modifier — Preceding unsigned comment added by 2001:630:12:106C:FC73:183E:A794:5102 (talk) 11:23, 13 May 2015 (UTC)


 * The article already mentions this in the network section. Zaereth (talk) 22:24, 7 January 2016 (UTC)

Semi-protected edit request on 21 March 2016
Please change "In cell biology there is recent evidence suggesting that the cytoplasm" by "In cell biology there is recent evidence suggesting that the cytoplasm and the membrane" to include recent results that suggest that also the lipid membrane behave as a colloidal glass(as is shown in the reference number 38[^ Munguira, Ignacio (9 February 2016). "Glasslike Membrane Protein Diffusion in a Crowded Membrane". ACS nano. doi:10.1021/acsnano.5b07595]).

176.190.108.134 (talk) 23:13, 21 March 2016 (UTC)
 * Red information icon with gradient background.svg Not done: please establish a consensus for this alteration before using the template.  B E C K Y S A Y L E S  06:24, 25 March 2016 (UTC)

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Ingredients
The list in the Ingredients section is highly suspect. All the ratios information is from this source: I'm not convinced how authoritative it is. The exact material ratios are suspicious, since a range of ingredient ratios are used (e.g. borosilicate glasses). Better references are needed for each of them. For now, I'm removing the ingredient percentage. T.Shafee(Evo &#38; Evo)talk 08:08, 2 January 2017 (UTC)
 * Mining the sea sand. Seafriends.org.nz (1994-02-08). Retrieved 2012-05-15.

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Semi-protected edit request on 30 January 2017
Under "Silicate glass" -> Ingridients-> 3. Sodium borosiliate glass, Pyrex -> line 3: (e.g. Pyrex) -> New: (e.g. Duran, Pyrex) -> And link on Duran Under "Silicate glass" -> Ingridients-> 5. Aluminosilicate glass -> New: Link on Aluminosilicate glass --Middlesea (talk) 14:20, 30 January 2017 (UTC) Middlesea (talk) 14:20, 30 January 2017 (UTC)
 * ❌ Pyrex is a the most well known example, Duran in discussed in the Borosilicate glass article. Polyamorph (talk) 16:12, 30 January 2017 (UTC)

Semi-protected edit request on 9 February 2017

 * 1) Sodium borosilicate glass, Pyrex: silica + boron trioxide (B2O3) + soda (Na2O) + alumina (Al2O3). Stands heat expansion much better than window glass. Used for chemical glassware, cooking glass, car head lamps, etc. Borosilicate glasses (e.g. Duran, Pyrex) Soecor (talk) 14:33, 9 February 2017 (UTC)
 * ✅ Polyamorph (talk) 16:21, 9 February 2017 (UTC)

Pyrex
Since Pyrex brand products are not made of borosilicate glass since before the existence of Wikipedia, it would only be appropriate to not mention as if they are. http://www.snopes.com/food/warnings/pyrex.asp — Preceding unsigned comment added by Ibmua (talk • contribs) 22:42, 19 February 2017 (UTC)
 * Might be true in North America, but not elsewhere. It is explained in the Pyrex article. Polyamorph (talk) 10:29, 20 February 2017 (UTC)

Picture of lead glass
Not sure this can be the case. From what I remember, PbO glass has a faint greenish colour. This is more likely sodium borosilicate glass (i.e. pyrex). User:Rvlaw 4 January, 2016


 * I'm not sure which photo you're referring to. If it's the welding photo, that is definitely common lead-glass used in neon-lighting construction. I have a ton of it at home. It's very clear in thin sections, but in cross-section (when I cut the tube and look down its length, it is very yellow in color (as opposed to the turquois-blue of soda-lime or the white of fused silica). Borosilicates can have a range of colors, from white BK7 to brown Pyrex. Greenish-blue tint is usually from iron. Zaereth (talk) 22:31, 7 January 2016 (UTC)

Really? What causes the colour in the flame then ? When you heat lead glass you usually get a grey-white flame from the ions in the glass. Likewise, if you heat soda glass you get a yellow flame from the Na ions, the same occurs with sodium borosilicate glass (i.e. pyrex). I don't know that much about the subject so I might be wrong. User:Rvlaw 21 September, 2016 —Preceding undated comment added 09:18, 21 September 2016 (UTC)


 * Couldn't tell you much about the color of the flame, except that I have some fused silica, soda-lime, and borosilicate here that I could try it on and let you know. As the person doing the welding (my sister holding the camera), I can tell you that it is definitely lead-glass, used in neon-lighting construction. I bought a whole case of feed-tubes from the local supply house for about five bucks. (Sold by weight, but roughly 1000 4' sticks to a case.) The OD is 5mm and the ID is 3mm. The flame is a carburizing flame from a simple, handheld propane-torch. (No oxy to make it neutral. Such high temps are simply not needed for lead glass.) The manufacturer of the glass tubing is Voltarc, which I purchased from Sun Supply many years ago. Zaereth (talk) 11:11, 21 September 2016 (UTC)


 * I tried it with other glasses and get the same yellow flame with the propane torch. I'm guessing this is from the unburned carbon, reigniting as it flows past the hot glass. Carbon has a strong spectral-line in the yellow. The lead glass can be welded at a reddish-orange heat. Soda-lime at an orangish-yellow. However, the fused-silica and borosilicate require an oxy-gas flame (preferably oxy-hydrogen), and they melt at a white-hot temp. It's impossible to see the color of the neutral flame because these glasses are so much brighter. These give off so much light it's more like greybody radiation rather than blackbody (the glass is not opaque to its own light) and require a welding helmet with a minimum shade-10 filter just to even see them. I hope that helps. Zaereth (talk) 18:12, 21 September 2016 (UTC)
 * Hi User:Rvlaw. I was talking to a friend of mine, and this came up. She's in a position to know these things, and what she said is that you need to use an oxidizing flame to get the effect that you're talking about. You don't use those for welding ... nor, for that matter, any other manufacturing process I know about. (Too destructive. I'll have to refill my O 2 bottle and try it.) Zaereth (talk) 01:26, 25 March 2017 (UTC)

Semi-protected edit request on 23 May 2017
May I please edit this page??? 135.0.61.60 (talk) 22:07, 23 May 2017 (UTC)


 * Due to persistent vandalism this page has been semi-protected from editing. This means that you need to be an auto-confirmed user to edit the article. If you like, you can create an account, then make some constructive edits to other articles, and within a short time you will be able to edit this page.


 * Otherwise, you can make a specific request here and people like myself can decide if it is constructive or not and edit the article for you. Please be specific in your request (ie: this needs to be changed to that because...) because general or vague requests will typically be ignored. Zaereth (talk) 00:02, 24 May 2017 (UTC)

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Misleading image
Image at Glass is misleading and wrong - silicon is shown as 3 coordinate - even as a 2d projection this error is not acceptable.5.198.10.236 (talk) 08:48, 10 April 2018 (UTC)
 * That is the conventional way of representing a continuous random network that you would find in all sources from Zachariasen's original model. Polyamorph (talk) 10:13, 10 April 2018 (UTC)

Semi-protected edit request on 25 October 2017
I understand that Glass is NOT a solid, is liquid, but at our atmospheric temperature it solidify. 104.36.138.18 (talk) 15:53, 25 October 2017 (UTC)
 * Yes, but just what did you wish to change? Vsmith (talk) 16:09, 25 October 2017 (UTC)
 * "Yes,..."? Why did Vs say that, rather than "No, but in accordance with your request via the title of your talk-contrib immediately above, specifically what did you wish to change or have changed?" ?? --Jerzy•t 20:39, 31 May 2018 (UTC)

Lime
change ((lime)) to ((Lime (material)|lime)) — Preceding unsigned comment added by 2601:541:4500:1760:F5D7:5960:169F:B409 (talk) 14:52, 11 November 2018 (UTC)


 * ✅. By the way, links use brackets: ..., rather than parentheses: ((...)). –Deacon Vorbis (carbon &bull; videos) 15:02, 11 November 2018 (UTC)

sustained glass production in South asia is earlier than Mesopotamia, Egypt
Bead Technologies at Harappa, 3300-1900 BC: A Comparative Summary JONATHAN MARK KENOYER 115.135.118.112 (talk) 18:38, 5 January 2019 (UTC)

A Commons file used on this page has been nominated for deletion
The following Wikimedia Commons file used on this page has been nominated for deletion: Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 19:06, 21 June 2019 (UTC)
 * Healing the World (Tikkun).jpg

Formability
The lede refers to the formability of glass but that linked page makes no reference to glass, only to metals. Perhaps someone with knowledge in these areas (i.e. not me) can either add a referenced sentence to glass being formable on the linked page or, if the use of the term in the lass article is incorrect, replace it with another, more appropriate term. thanks Geopersona (talk) 04:58, 22 March 2020 (UTC)
 * In some sense this is more a problem with the article formability than glass. This is referenced in the article with the sentence: In the manufacturing process, glasses can be poured, formed, extruded and moulded into forms ranging from flat sheets to highly intricate shapes.[54]. But perhaps malleable is a more accurate term? Cheers Polyamorph (talk) 12:03, 22 March 2020 (UTC)
 * Or ease of manufacture into different shapes? Polyamorph (talk) 12:09, 22 March 2020 (UTC)

Broken glass
I agree that image doesn't fit in the section where it exists, but I think it's a little strange that the article on glass doesn't have any section about fracture mechanics or failure mechanisms. Is there something I'm missing, or is this just conspicuously absent? jp×g 08:28, 15 December 2020 (UTC)
 * The physical properties section states that glass is brittle and will fracture. There are links to Tempered glass and Laminated glass. There could perhaps be an expansion of this section to include fracture mechanics and thermal shock etc. but as this is a GA these will need to be well sourced and any figures will need to fit the text. Polyamorph (talk) 09:28, 15 December 2020 (UTC)

Semi-protected edit request on 20 March 2021
Please remove this

rather than true glass, which did not appear until 15th century BC.

and add this

rather than true glass, which did not appear until the 15th century BC.

Thank you. 108.39.223.134 (talk) 18:14, 20 March 2021 (UTC)
 * Yes check.svg Done &#8209;&#8209; El Hef  ( Meep? ) 21:25, 20 March 2021 (UTC)

Article was originally in American English before being changed to British English in February of 2020
This article's first stub was originally in American English and the vast bulk of its edits remained in American English until a rework of the article by user Polyamorph in February of 2020. A cursory review of the history reveals this, to wit: https://en.wikipedia.org/w/index.php?title=Glass&oldid=343117046. This is the original stub and it uses the American spelling of the word "color".

The relevant policy at https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style#Retaining_existing_styles states:

"When an English variety's consistent usage has been established in an article, maintain it in the absence of consensus to the contrary. With few exceptions (e.g., when a topic has strong national ties or the change reduces ambiguity), there is no valid reason for changing from one acceptable option to another.

When no English variety has been established and discussion does not resolve the issue, use the variety found in the first post-stub revision that introduced an identifiable variety. The established variety in a given article can be documented by placing the appropriate Varieties of English template on its talk page."

I endeavor to give here the most fulsome picture possible of the history of the article to emphasize the point. Apologies if this is lengthy, I have tried to make it as comprehensible as possible, with details.


 * Circa February 10, 2020, a substantial and lengthy series of edits was conducted by user Polyamorph, who had previously done work on the article going back for over a decade. Interestingly, his or her prior edits were all in American spellings. Note:


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=939958647 -- an edit by Polyamorph on 9 February 2020, in which American spellings are exclusively used. This was one of the last before he reworked the article and changed things


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=932226701 -- an edit, chosen at random (not cherry-picked), from December 24, 2019, in which American spellings are exclusively used


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=771353809 -- an edit, chosen at random, from 21 March 2017 in which all spellings are American and none are British in the article


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=632837645 -- an edit by Polyamorph from 7 November 2014 in which all spellings are American and none are British


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=608178776 -- an edit chosen at random from 12 May 2014 in which all spellings are American and none are British


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=438502355 -- an article from 9 July 2011 in which the word "color" appears 13 times, "colour" appears zero times in the text body (once as a citation); "fiber" appears once and "fibre" appears twice


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=314162573 -- an edit by Polyamorph from 15 September 2009; "color" appears 28 times, "colour" appears zero times in the text body (twice in citations); "fiber" appears 16 times and "fibre" appears once


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=192514783 -- a randomly chosen edit from 19 February 2008 which is among the most evenly split. "Color" appears 14 times and "colour" appears 14 times, as well. "Fiber" appears 4 times and "fibre" appears 3 times


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=1062976 -- a randomly chosen edit from 20 June 2003, early in the article's history; spellings are exclusively American with the exception of a single use of "fibre optic"

User Polyamorph had been heavily involved in creating the article over a period of over a decade and operated within the existing style of American spellings until his rework that commenced around February 10 of 2020. As the history of the article shows, there was a very great number of edits by Polyamorph during which the body of the article was significantly expanded and improved. The first edits by Polyamorph retained the pre-existing American spellings, as is seen in https://en.wikipedia.org/w/index.php?title=Glass&oldid=939963111 on February 9 of 2020 which hails from early in his process. It was not until these series of edits that Polyamorph began to change the spellings, which was not substantively related to the work he or she was doing on the article's text:


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=940160047 & https://en.wikipedia.org/w/index.php?title=Glass&oldid=940159649 -- 10 February 2020, changed color to "colour" for no relevant reason


 * https://en.wikipedia.org/w/index.php?title=Glass&oldid=940398312 -- 12 February 2020, this is the first time that "fiberglass" turns into "fibreglass" throughout the article

A review of the History for the Talk page shows that there was no template for an English version until after Polyamorph changed the spellings to British, at which point a British English template was added. This occurred at https://en.wikipedia.org/w/index.php?title=Talk:Glass&oldid=940159817 on 10 February 2020 with the edit summary "BE" indicating that Polyamorph was claiming the article to be in British English. Although there was no formal template added until this point, policy does not require there to be a template in order for an article to have established an English standard. The history of usage in the body of text, and specifically the standard used in the first revision edit in the history, are controlling. An examination of the history clearly shows that the article was both primarily in American English over the course of its history and that its original post-stub was also in American English, which is conclusive.

It appears that user Polyamorph felt that substantially reworking the article in February of 2020 represented a valid occasion to spontaneously change the spellings from American to British. However, he is incorrect on that score. While I commend his enthusiasm for editing the article, changing the spellings was inappropriate. This is why I have undone it. I have left the substance of his article improvement intact, however. PhilHudson82 (talk) 05:59, 19 April 2021 (UTC)


 * Sorry why is this so important? I write in British English and wrote most of the content. Prior to this there was a mix of ENGVAR. Please focus on something more constructive. Polyamorph (talk) 10:51, 19 April 2021 (UTC)
 * It is regarded as important, but looking at the history I can't detect any engvar in 2001; by 2004 it used both "colour" and "color" and so on, and seems to have been mixed for many years thereafter. The only discussion in the archives supported BREng - see Talk:Glass/Archive_4 from 2014-15. Perhaps you could point to a "pure American" version in the history? Johnbod (talk) 14:23, 19 April 2021 (UTC)
 * Not important enough to warrant a wall of text detailing very specifically my editing behaviour. IMO. There was mixed ENGVAR throughout the history of the article. Polyamorph (talk) 14:33, 19 April 2021 (UTC)

Glass art

 * Rather more important than asking for sky-is-blue references on improvements to a truly piss-poor art section. I've no idea what User:Chiswick Chap was doing passing that at GA. Johnbod (talk) 14:52, 19 April 2021 (UTC)
 * How rude, but easily answered as a matter of fact: art is a subsection of this article on glass-as-a-material, and three articles that deal with glass-in-art are linked. The GA criterion here is "covers the main points", which I take to be that glass has been and is used in art, basta. Detail is for the linked articles. Believe me when I say that the article's coverage of art was greatly improved in the GA process. Chiswick Chap (talk) 15:04, 19 April 2021 (UTC)
 * I can believe that, but it was still terrible, with several actual inaccuracies, and unduly small compared to the physics stuff. There is also next to nothing on glass as an industry. Johnbod (talk) 15:26, 19 April 2021 (UTC)
 * So in your opinion ENGVAR pedantry is more important than reliable sourcing the content you add. OK then...I'll just removed any unsourced content, easily solved. Polyamorph (talk) 16:51, 19 April 2021 (UTC)

Ok, to me this seems like much ado about nothing. To a very small number of people (relatively speaking) the superiority of British over American English (or visa versa) seems like this all-important thing, and that has always puzzled me, because it is all just idiomatic. The question I would have to ask them is why? Sometimes there are very good reasons, and I can agree with those, but like 90% of the time the answer to this question tells me a lot about the person answering it, but little in the way of why it really matters to the article.

I'll admit, I've always been a little fascinated at how some British people cling so hard to these French spellings, but equally fascinating are the Americans who reject them with equal fervor/fervour. But then again, I've always been fascinated by the brain, the mind, and the history of the English language. ("If you want to understand a people, first learn their language, to learn how their minds work, then understand their religion so you'll know their hearts.") Spelling standards are relatively new. Just try reading Old or Middle English.

In my opinion, it doesn't matter one way or the other, as long as the article is consistent throughout. This article really started off with both, as the liquid/solid debate took off quite rapidly very early on, and it remained that way for quite a long time, and nobody seemed to care. In any of these conversations, I have not seen anyone even try to give a compelling, logically valid reason why it should be one over the other. What I do know is: starting off with a combative stance like this and trying to play some kind of blame game is an extremely poor way to try and build consensus for whatever point a person is trying to make. If there is a good reason to change it, people should just start with that, and you'll get a lot more accomplished. The rest is all just a distraction and is likely to have the opposite effect as intended.

The same really goes with the art. I'm often a very blunt critic when it comes to writing, but if I just say things like "terrible" and stop there, then I'm nagging. It's always better to point out actual problems and give possible solutions, or try to fix them yourself, but I'd like to see sources of equal or better quality than is found in the rest of the article. Polyamorph and I talked about this during the GA assessment, because neither of us know jack about art, so we did the best we could with the few resources we had, knowing that it could likely use some improvement. So why not just improve it? It makes little sense to start off combatively. Zaereth (talk) 18:38, 19 April 2021 (UTC)
 * I did better than that - I just rewrote it to be a lot less terrible. I think if you look at the recent edits here you can see who started combative, & who then upped the stakes. Sources will follow. Johnbod (talk) 21:05, 19 April 2021 (UTC)
 * You repeated content that already existed in the history section, which is actually making matters worse. And it was unsourced. And take responsibility for your own behaviour here please, if you want improvements then you have to work with us which means adjusting your attitude significantly. Polyamorph (talk) 21:34, 19 April 2021 (UTC)
 * Thanks I'll add to that, if an editor is willing to help improve the glass art section then they are most welcome, or any other section (such as industry). But please make sure any additional content is sourced and doesn't repeat information already provided (e.g. in the history section). I also agree with  that while it is essential we have a section on glass art, in depth coverage belongs in the three main articles that are clearly linked (Studio glass, Art glass, Glass art). Actually if those articles were improved it would be a lot easier to summarise here. Polyamorph (talk) 18:55, 19 April 2021 (UTC)
 * You seriously think we are within a million miles of anything that could be called "in depth coverage", or that anyone proposed that here??? Johnbod (talk) 21:05, 19 April 2021 (UTC)
 * This article is about the material. There are 3 main articles on glass art which need significant improvement, it would be wise to improve the content there. We don't need in-depth coverage here, a summary is fine. Of course improvements are welcome. Polyamorph (talk) 21:31, 19 April 2021 (UTC)


 * I'll start by saying that this should probably be in a different section, because it's an entirely different issue from Phil's problem. Sometimes less is more. As contradictory as that sounds, the quicker and briefer that you can get the gist of the information across; the better it will usually sound to the reader, and the easier it will be for them to read and comprehend. While I see what you were going for Johnbod, I also see a lot of personal insight and opinions woven into the work. For example, "best in Europe" is an opinion, which would be better explained in terms of what makes it better. Likewise, "terrible" is an opinion, but it does nothing to help us see what you find so terrible about it.


 * In my opinion, this is an article about the material, so that is really the main crux of this entire article. We should explain what it is, how it's made, where it came from, and briefly touch upon all its uses, but we don't need to give undue weight to any one of those uses. This is what I'd call a "parent article". This subject is far too large to fit everything in one article, so it all is very briefly summarized here, with "sub-article" links to the subordinate articles. It really serves as a brief summary and a sort of directory to the relevant articles.


 * For example, Energy is the parent of Kinetic energy and Potential energy. Potential energy, in turn, is the parent of gravitational potential energy, chemical potential energy, etc... As an analogy, the Mirror article discusses the object, but gives only very brief summaries of their uses with main-article links to the sub-articles. Anyone who wants more info can click on those links to learn more.


 * Likewise, an article I am rather proud of is Basic fighter maneuvers. It gives the most basic, general information about the principles, concepts, history, and uses, but the maneuvers themselves need only the briefest of descriptions with main-article links. See, the vast majority of people who view an article will never bother to read the whole thing. In fact, readers are by far in the minority. The largest percentage of people are just researching an answer to a very specific question, followed by those only looking to answer, "What the hell does this word mean?" For all these people, it's best to keep the parent article as generalized and brief as possible, and put the details in the sub-articles. It's just a more logical order, and makes everything easier to read and find.


 * For this article, I would just briefly summarize the glass art article in one or two paragraphs, whatever is concise yet still precise, and let that article serve as the parent for all the other art articles. Likewise, those article could use a little more of the science, such as explaining how adding different colors can create stresses in the glass. (Why stained glass is usually leaded together rather than welded.) That's my two cents. I hope that helps. Zaereth (talk) 22:47, 19 April 2021 (UTC)
 * Well, I was thinking this might be better stripped down a bit and renamed to Glass (material science) or Glass (material).  But if you are going to take the plain term as a title, you can't just say "of course we only mean the material science". You need to cover what readers will reasonably expect from the general title, which certainly includes the history, industry and art.  And do it properly. Without complaining about it.  The article seems to me to go into tremendous detail on the science, though no doubt there is much more to say, and to be unbalanced in that respect, given its general title.  Johnbod (talk) 02:46, 20 April 2021 (UTC)


 * Glass as a material is clearly the primary topic and does not require disambiguation in the title given its ubiquitous use in modern society. Glass art is a sub topic and an application of the material. So I agree with Zaereth, we should only be providing a summary here, linking to the relevant articles, as we already do. Although, just to be clear, I do agree with you Johnbod that our summary coverage of glass art should be improved. Polyamorph (talk) 06:43, 20 April 2021 (UTC)
 * Also, for the record, during the GA review I actually twice requested expert assistance for the Glass art section at the visual arts wikiproject (where Johnbod is an active participant) and got crickets Wikipedia_talk:WikiProject_Visual_arts/Archive_20. Polyamorph (talk) 08:37, 20 April 2021 (UTC)
 * Ah, so it's all my fault then. Johnbod (talk) 13:13, 20 April 2021 (UTC)
 * I did not say that, but you were aware of the issues at the time of the GA review and only now, a year later come here to tell us what a shit job we did. I would be very happy to work with you to sort out these problems, if you would like our assistance then please start a new section here on what you think is missing or needs doing and how we can help. In the meantime I am closing this specific thread. Polyamorph (talk) 14:39, 20 April 2021 (UTC)
 * Actually, I have no recollection of seeing that, & if I had, I might have helped. Johnbod (talk) 14:52, 21 April 2021 (UTC)
 * OK, I seem to recall you editing the article around the time of the GA review, but it doesn't matter, my only point was that this isn't something I intentionally tried to brush under the carpet. Polyamorph (talk) 15:32, 21 April 2021 (UTC)

More general points

 * The lead is much too short for the size of the article. Per WP:LEAD all 4 available paras should be used. Johnbod (talk) 14:52, 21 April 2021 (UTC)
 * I can't judge the scientific aspects, but the history section seems very weak on the social history of glass. People (especially those with homework to do) are likely to come here to find the answers to questions like "When and where did people start using glass in windows/drinking out of glasses as a common thing?"  They won't get much help here. Johnbod (talk) 14:52, 21 April 2021 (UTC)
 * Many of the references, especially in the history section, are weak, & some probably not RS. Generally the references seem to be a collection of individual web sources, in an all too familiar WP pattern. None of the many, easily available, large books actually about glass seem to be used much, which might give a more balanced view. Johnbod (talk) 14:52, 21 April 2021 (UTC)
 * There are 16 See also's, much too high a number, and probably not the right ones. They should be worked into the text or just cut. Johnbod (talk) 14:52, 21 April 2021 (UTC)
 * Thanks Johnbod. For the lead, sure lets expand it. Most references cited in this article are reliable, but as you say there are some web sources in the history section are probably not quite so good. There is actually a substantial amount of history detailed in the 1911 Encyclopædia Britannica on glass which is public domain material. In fact this is cited in the history section but could be used more extensively. It's not much use for 20th century history but seems a great resource for the early history. Any recommendations for any other good books on the history of glass or glass art? Cheers Polyamorph (talk) 08:25, 23 April 2021 (UTC)
 * In general it is best to avoid sources over a century old. On a google search, the kind of secondary/tertiary sources we should using probably include:


 * 
 * Glass: A World History, By Alan Macfarlane, Alan Macfarlane Gerry Martin University of Chicago Press, Gerry Martin · 2002
 * 
 * 
 * Maybe

On the art side, I only have (just on general glass): -but I wouldn't add there yourself. The Corning Museum has a lot online, & there are Metropolitan Museum catalogues online. Johnbod (talk) 16:09, 23 April 2021 (UTC)
 * Battie, David and Cottle, Simon, eds., Sotheby's Concise Encyclopedia of Glass, 1991, Conran Octopus, ISBN 1850296545
 * Osborne, Harold (ed), The Oxford Companion to the Decorative Arts, 1975, OUP, ISBN 0198661134 (20 double-column pages in the main "glass" article)


 * Thanks. Some comments:
 * [1] Shelby is a Glass scientist, we already cite in the glass types and colour sections. It is a good resource for glass science but only a small amount on history of glass.
 * [2] The Macfarlane book looks promising but unfortunately I can't even see a preview.
 * [3] Shackleford we also already cite, again is an excellent resource for the glass science.
 * [4] is a good reference for physical properties of glass, which would be useful in the Properties and Types sections. But in this reference there is a bibliography for history of glass, including,.
 * I don't have much time right now. But when I do (likely in a few weeks) I will take a look at improving the history section. If you would like to have a go at the art section (if you have time) then that would be very welcome. Polyamorph (talk) 18:35, 23 April 2021 (UTC)
 * Yes, the 2nd one looks best on the history, which the art books also cover. I will return to the art section, but after circling round the the truly awful glass art etc. I hope the scope of that vs art glass and studio glass is already clearer. I've just discovered we don't have anything at all on cut glass, which redirects to something completely different; etc. So I may be some time. David Whitehouse (your first link) is a top guy, long with the Corning Museum, they have tons of his stuff online. Johnbod (talk) 19:45, 23 April 2021 (UTC)
 * Hi, just to let you know, I haven't forgotten about this. I'm just very busy in real-life. Once I get some free time to read the references I will start working through the history section. Polyamorph (talk) 14:35, 22 May 2021 (UTC)

Semi-protected edit request on 21 May 2021
"Although brittle, silicate glass is extremely durable and many examples of glass fragments exist from early glass-making cultures." makes no sense. Suggestion is to remove "Although" from the beginning. MattDaCatt (talk) 23:43, 21 May 2021 (UTC)


 * The sentence is colloquially correct, although you're right in that, in the very technical sense, "although" is a conjunction, thus in formal writing is not normally used to begin a sentence, although people do it all the time. It's like beginning a sentence with "and" or "but". What it means is that glass still has very high yield strength, compressive strength, tensile strength, and hardness despite having rather low shear strength and fracture toughness. However, simply removing the word would definitely not make sense, because the adjective "brittle" would be sitting there all alone. I changed it to a formally correct construction, while still maintaining the original meaning. Zaereth (talk) 01:49, 22 May 2021 (UTC)
 * see above Run n Fly (talk) 14:18, 22 May 2021 (UTC)
 * Yeh, that would be my writing, I'm not very good at knowing the rules when it comes to formal writing...I don't remember ever properly being taught! Thanks for fixing Polyamorph (talk) 16:49, 22 May 2021 (UTC)
 * The adjustment doesn't solve the problem that "brittle" and "durable" appear to be contradictory, unless you think about it. "Durable" is probably not the best word, as in practice non-brittleness is something we expect from "durable" things. Another issue is that ancient glass tends to be very thin by modern standards. It would be better to say something like "Although brittle, buried silicate glass will survive for very long periods if not disturbed, and many examples of glass fragments exist from early glass-making cultures."  In fact we have more Roman glass than from other periods before the 17th century, if nearly all as fragments (Battie & Cottle, 26).  Johnbod (talk) 17:31, 22 May 2021 (UTC)
 * Your re-wording sounds good to me. Polyamorph (talk) 18:18, 22 May 2021 (UTC)


 * Looks great to me. It helps clear up any confusion. I wasn't really sure what Matt was asking for, so took a shot in the dark that it was a simple grammatical problem. Go ahead and change it. I'd do it myself but I'm going to be off in the wild with the bears and moose and wolves, and the dreaded mosquito. Zaereth (talk) 01:58, 26 May 2021 (UTC)

English
Write short notes on

Some properties of glass

Coloured glass 2401:4900:5026:67A9:FF03:1196:BBB0:B046 (talk) 13:40, 29 November 2021 (UTC)

First sentence
The first sentence is written rather awkwardly:

"Glass is a non-crystalline, often transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics."

I propose changing it to:

"Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative uses such as window panes, tableware, and optics." — Preceding unsigned comment added by 71.11.5.2 (talk) 20:46, 4 May 2022 (UTC)


 * Done. Zaereth (talk) 18:42, 9 November 2022 (UTC)
 * I do agree - Proceed Sandkuhle (talk) 07:29, 10 November 2022 (UTC)

Hi! Are glass knives a noteworthy use?
For the purpose of inclusion in the uses section of this article, (for example, as surgical implements, or as cultural objects vis. obsidian tools) should glass be mentioned in the context of cutting tools, like knives? Honestly not sure if it would be outside of the scope of the article, since it's a rather specific niche, wanted to field it for discussion : )  Atomic putty? Rien!  16:22, 22 May 2023 (UTC)


 * There is an article on this topic at Glass knife. Plant surfer  16:43, 22 May 2023 (UTC)

Main image
I prefer to have the current image of a glass building facade, windows are a ubiquitous use of glass and would be immediately recognizable. They are not a narrow view of glass at all, window glass is among the most widespread applications of glass materials. It is also the image used when the article was promoted to GA. The recent alternative and more niche examples would be more suitable as the lead images of glass art / glass manufacturing or related articles. Polyamorph (talk) 09:30, 23 May 2023 (UTC)


 * The making of a tiny glass elephant 04.jpg adding some molten glowing glass to cool transparent glass]]
 * The current picture only show glass in 1 type, in 1 use case. I think it's an oversimplification of what glass is, and it give of corporate and "generic picture" vibes. A better picture would show glass in its 'raw' form (see for example pictures in Salt), which can be used to create all kinds of stuff, and that's the reason why I pick that "molten glass and cool glass" picture. I do agree that the pick might not be immediately recognizable though, but I think it's a worthwhile tradeoff. CactiStaccingCrane (talk) 16:12, 23 May 2023 (UTC)
 * The current picture is instantly recognisable as glass of the most common and widespread type. An image showing the making of a tiny elephant out of glass does not. We have images throughout the article of a wide variety of different uses, including its molten form. I don't see any reason for a tradeoff here. Polyamorph (talk) 17:55, 23 May 2023 (UTC)
 * For me it's like using table salt pic in the Salt article, or using oak wood in the Wood article. It's just not a good representation for the topic. CactiStaccingCrane (talk) 04:12, 24 May 2023 (UTC)
 * We're not going to agree on this, hopefully other users will come here and comment. If not we can start an RFC. Cheers Polyamorph (talk) 04:44, 24 May 2023 (UTC)
 * I think that's fair too :) Thanks for your willingness to discuss. CactiStaccingCrane (talk) 04:46, 24 May 2023 (UTC)
 * Thanks. Also note, the current image is a Quality image - that's not to say an alternative image of similar quality cannot be found or that your image couldn't be classified as a quality image. One day, I'd like this article to get to FA, but it was a lot of work to get to GA and I haven't done the improvements to the Glass Art section I promised I'd do...still, there is no time limit here! :) Polyamorph (talk) 07:21, 24 May 2023 (UTC)
 * Very classy and classical debate style, you two. For what it's worth, as the first respondent, I !voted without reading this previous discussion, or the prompt (guess I was a little on auto-pilot, having responded to a large number of these "choose the lead image" RfCs over the years, which are arguably one of the more (if far from completely) subjective calls we can be asked to make on the project.  Anyhow, what I'm getting at is that I saw the value in both photos similarly to each of you, so it was interesting to read those descriptions so cogently (but also clinically and neutrally) discussed. I mean maybe it is a testament to how much acrimony I have seen here over recent years that two contributors just lobbing a relatively minor issue back and forth without losing their minds over it stood out...but I'd rather take a more positive outlook and say that there was just something very traditional in the way you each took turns in succinctly presenting your cases. SnowRise let's rap 10:41, 30 May 2023 (UTC)
 * Sorry, but I'm not the most civil ones out there (evident by my recent ANI thread and sometimes flamboyant comments). I should work on civility more. CactiStaccingCrane (talk) 13:14, 30 May 2023 (UTC)
 * You've been perfectly civil here :) Polyamorph (talk) 05:12, 31 May 2023 (UTC)

RFC on main image
Should the current image be replaced? Consensus is needed on the most appropriate image to use as the main image in this article. The current image shows a glass building facade; it is a Quality image, used when the article was promoted to GA, and is instantly recognisable as glass of the most common and widespread type. However, it has been criticized as an oversimplification of what glass is and a somewhat corporate and "generic picture". An alternative has been proposed which shows a glass figurine being manufactured; while it might be less recognisable it shows glass in it's 'raw' form in both the molten and solid-state, indicating how glass can be used to make a variety of products and forms. The two images under discussion are provided below.

Best wishes, Polyamorph (talk) 07:54, 30 May 2023 (UTC)


 * Current: Either would be acceptable at first blush, but if put in the position of choosing between the two, I gravitate more towards the one that displays the glass in a finished state and in one of it's more practical and common applications. The article would not be hurt either way, though. S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 10:15, 30 May 2023 (UTC)
 * I don't think either is ideal; further suggestions please (anyone)! Johnbod (talk) 14:49, 30 May 2023 (UTC)
 * Hmm... if anyone want to have a crack at this see Commons:Category:Glassblowing
 * ]] CactiStaccingCrane (talk) 16:26, 30 May 2023 (UTC)
 * Or Commons:Category:Glass! Johnbod (talk) 16:41, 30 May 2023 (UTC)


 * Current: If it ain't broke, don't fix it. Tom94022 (talk)
 * Current: Sadly, most people associate glass with windows and then beverage glasses before they think of art glass. Plant surfer 18:27, 30 May 2023 (UTC)
 * Current, it's obviously glass; the proposed image wasn't obviously glass until I clicked through to the big image at Commons and examined what was going on. It could have been, for example, a blacksmith working some very hot iron. -- Red rose64 &#x1f339; (talk) 21:14, 30 May 2023 (UTC)
 * If we must change the image, I think that ideally, we should find a single photo that in one image shows several different applications for glass - for example, c:File:Bundesarchiv B 145 Bild-F023259-0002, Bonn, Landesvertretung Baden-Württemberg.jpg shows glass used for drinking vessels, vases and other decorative items, and also as shelving. I'm not saying to use that particular image - it doesn't show any windows or mirrors, among others. -- Red rose64 &#x1f339; (talk) 09:41, 31 May 2023 (UTC)
 * That was my sentiment as well when I looked through our options in terms of other images: really only those with multiple varieties of glassware seemed particularly appropriate. But then the problem there becomes that suddenly we are causing potential confusion about which article is the one about "glass" (a material) and "a glass" (as in an example of specific type of glassware used for drinking). In any event, I still have yet to see an image that seems as utilitarian as the current one. I suspect that whoever added it did a fair bit of searching before settling on it by default. <b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 09:35, 1 June 2023 (UTC)


 * Current Nothing wrong with the current image. The critique of being "corporate" and "generic" is meaningless and may actually support the use of this image. –<b style="color:#77b">Laundry</b><b style="color:#fb0">Pizza</b><b style="color:#b00">03</b> ( d c̄ ) 05:36, 31 May 2023 (UTC)
 * Current image is more suitable because it represents the word "glass" better. The proposed image is very neat on its own accord, of course. Merko (talk) 18:28, 1 June 2023 (UTC)
 * I think both look really good. The second image is more of a primitive version showcasing a human interfacing with its production. SWinxy (talk) 00:11, 2 June 2023 (UTC)
 * Current. It's more practical and recognizable and represents possibly the most common use of glass. The other picture is great, but it feels too specific, especially since there's already a page for glass art. If the current image seems dull, there are probably more interesting images of glass facades that could be used. Pillowcrow (talk) 18:22, 2 June 2023 (UTC)
 * Current. I think the general reader would most likely associate glass with the form that is displayed in the current image. As has already been mentioned, the proposed replacement image is too vague and can even be mistaken as a blacksmith working on iron. JoseJan89 (talk) 01:53, 6 June 2023 (UTC)
 * Current - If the choice is only between the two, then I'd have to go with the current image hands down. The other is a fine image, but is a bit too busy for the opening pic and difficult to really see in a thumb view. I had the same reaction when someone once picked my own glass-welding image for the lede. I mean, I was honored someone chose it, but I took that shot for the welding article and thought it was too busy for the lede image of this article, so I took a simple picture of a jar and replaced it with that. Still, I'm no photographer and didn't mind having those images replaced with the current.


 * I will say that the lede image should be the best, highest-quality image we can find, and we are by no means limited with these two options. It should be a simple, portrait-style image with the subject facing (or looking directly at, as the case may be) the camera. It should have a good background that contrasts well yet does not detract from the subject, but rather highlights it.


 * The problem I see with the current pic is that it lacks any background to provide the reader with a point of reference. Don't get me wrong, it's a very artsy picture, like the kind you'd hang on a wall in a high-class restaurant or an art gallery, but it's a bit too close for context. It's like those artsy pics where they take really close shots of an insect's eye, or an orange peel, or whatever, and let you try to guess what it really is. That's what I mean by no context. It's pretty easy to see it's glass, but I have to read the caption to tell it's the face of a building. Even with inanimate objects, I think it's still best to go with a simple yet high-quality, portrait-style image that best represents the subject. Zaereth (talk) 00:38, 8 June 2023 (UTC)
 * @Polyamorph, could we close this RfC with consensus to keep the old image? CactiStaccingCrane (talk) 20:30, 8 June 2023 (UTC)
 * Sure, as the matter is not contentious and the consensus is clear, it doesn't need a formal close. Closing now. Polyamorph (talk) 11:12, 9 June 2023 (UTC)