The AFU and Urban Legend Archive
Science
Glass Flow
 old glass




Newsgroups: alt.folklore.urban
From: hsm@unislc.slc.unisys.com (Helge Moulding)
Subject: Re: Old windows thickening at the base?
Date: Tue, 30 May 1995 17:11:33 GMT

Someone had asked,
: : Could the egyptians have found an extremely efficient way of blowing
: : glass or found aditives which stengthened the molecular bonds in
: : their glass?

And I quipped,
: >Sure. The famous glass pyramids of Bizet are proof of that.

: >(Where the hell have you seen man-made glass more than a few hundred
: >years old????!!!)

GryphonSus wrote,
: Try the Grand Rapids (MI) Public Museum, on Jefferson St.

Ah, yes. I did some reading on this business in the past few days. Glass has been around a while, indeed. Egyptians made mostly glass beads, although they did manage to pour glass vessels in sand molds. The folks in Carthage apparently came up with glass blowing, and did try their hand at slab pouring. The problem with slab pouring is, of course, that the glass isn't all that transparent...

I described an earlier version of producing crown glass, and my supposition of how window glass was produced without modern tech was all wrong. (They slab poured, and polished like the dickens. The pouring process was nothing like even, and resulted in a thickened edge on the side of the slab that had longer to cool as they used a roller to press the glass flat.)

I also found that glass coloring has been around forever. In fact, colorless glass is a lot more difficult to make than colored glass. Mostly, colorless glass is made by adding colorants that reduce existing, obvious color to a sort of gray, which is no longer noticable.

Glass flowing is a matter of silliness. Glass viscosity is around 10^13 poise, which amounts to forces several orders of magnitude greater than what is needed to break glass, should it flow perceptibly at room temperature -- even over several centuries.

Someone mentioned diamond on this subject, claiming it was a liquid because it evaporates. Was he trolling? -- 

        Helge "True, they aren't forever." Moulding
        (Just another guy with a simple .sig)



Any proceeds (net proceeds from merchandise sales) from TAFKAC solely benefit The Chuck Reed Fund.

Copyright Information

http://tafkac.org/