Slashdot Mirror

http://www.cmog.org/article/does-glass-flow

Old glass windows more likely show variability in width due to the way "plate" glass used to be manufactured... It was spun out into a sheet under centripetal force by swirling a blob of molten glass on a rod (the center swirly piece, broken off the rod, sometimes being seen in old cottage windows, etc).

I'd suspect cost.

Apparently, Corning's 'Fusion draw process' is what they use for LCD-quality glass(to avoid issues with defects on the contact side that the were having with float glass). And with that process you can get any shape you want, so long as it's a rectangular sheet. According to this interview, any shaping is done from the sheet stock, but before the ion-exchange toughening process:

"FLATOW: Why can't you - I'm sorry, why can't you make it the shape itself beforehand?

VELASQUEZ: Well, it's much cheaper, more effective, to make these large sheets of glass and then cut it later, as opposed to trying to mold - or mold from molten glass into a small part.

FLATOW: It's not having to do with maybe the glass being too tough or brittle to work with at that point?

VELASQUEZ: No, that's a good question, but we - the chemical strengthening process actually happens after our immediate customers have cut the parts down to the size, the shape of the parts."

So, if that is the case, presumably doing a dead-flat face just requires rounding off the corners a bit, possibly drilling out a speaker grille or front button(if either is within the glass area), and then calling it a day, while doing a 'watch glass' style curve would require starting with thicker sheet stock and grinding and polishing, in a shallow version of lenscrafting, which is presumably a more vexing process.

Probably doesn't help that(unless you got really fancy, selectively messing with refractive indices in parts of the face or something like that) the curved face introduces slight distortions of the image and makes the phone look thicker.

I'm not saying that these are sensible in the broad sense(especially given the number of phones I see out and about that were carefully designed and exhaustively manufactured to be slim, perfect, slabs of featureless unobtanium, which their owners promptly swaddle in garish silicone and blurry screen protectors, ending up with something substantially more expensive than, and neither much smaller nor much more attractive than, one of the less tacky discrete-faceplate designs; but that's my guess as to why it is what it is...

If you're in upstate New York, the Corning Museum of Glass has a nice history of glass, including modern technological applications. It is close to the Glenn Curtiss Museum which has early airplanes, bicycles, and motorcycles.

3) They are suppressing free energy? Why? Free energy would launch an incredible boom for economy, help greatly in pollution reduction, provide an excellent way of getting rid of oil dependency, provide instant cheap space exploration (and thus access to the vast resources on the moon and in the asteroid belt, for example), erase any poverty and/or hunger etc. So WHY should anyone suppress that? Can anyone tell me why?

First, a historical parable: http://www.cmog.org/index.asp?pageId=742

Moral: radical change to your economic base can be seen as a bad thing that needs to be repressed or, preferably, destroyed outright.

blow glass. that's pure chemistry.
http://www.cmog.org/index.asp?pageId=426

or spin fire. it's close to pure math. lol.
http://www.homeofpoi.com/

get primal! \m/ stack rocks and dance in your underpants. i do, and i still lurve my tecknowledgey. ;) peace.

1. Solids can also evaporate, but they do so at a rate about 10^40 slower than say water, so it makes no sense to say that solids flow.
2. Glass does not flow, in fact it is about a billion times less viscous than lead http://www.cmog.org/index.asp?pageId=745
http://www.glassnotes.com/WindowPanes.html
3. Hydrogen cools when heated, per the Joule-Thompson effect. Search for the second instance of "James Dewar" http://www.hq.nasa.gov/office/pao/History/SP-4404/ app-a1.htm

And yooouuurrrreeee out!

This needs some serious modding up. It's not like the scientists at Corning are playing around. Glass is their life.

At any rate, I just read this article yesterday, in fact. In my other life outside of real work, I'm a glass artist - I work mainly in stained glass ("cold" work, solid enough if you're trying to score and snap!) glass fusing ("warm" glass) and beadmaking or lampwork (at the very edge of "hot.") The properties of my meduim are fascinating to me.

One point that the above quoted article brings up is the "viscosity" or flow-ability (for lack of a better way of putting it) of the lead that is used in stained glass work. Buh-leeve me, the lead is far more pliable and - dare I say it? - "fluid" than the glass. So is the lead/tin solder used in another method of glass work, copper foil.

At any rate, the Corning Museum of Glass has a web site that's good for all sorts of glass surfing.

what the hell are you talking about?
Glass is a SOLID at room temperature. It does NOT FLOW SLOWLY.