Re: [CAD_CAM_EDM_DRO] re:flat glass

> Guess someone should tell the restorers of old houses! I've taken
> windows out of houses less than 100 years old, where the glass is at
> least twice as thick at the bottom (compared to the top)!
>
> Hope this helps.
>
> Ballendo
>

Glass just happens to be a second passion of mine.

It was installed that way. Glass manufactured before float or
precision rolled glass was 'blown' into a cylinder, the ends were
cut from the top and bottom, the remaining cylinder was slit
down one side and the cylinder was allowed to 'unroll' where it
was annealed. This lead to significant variations in glass thickness.

Installers would then make sure to place the thicker portion of the glass
at the bottom of the frame. This is more structurally sound as the thick
part was better at supporting the thinner part.

This was the case in the medieval cathedrals several hundred years
old. The variation in thickness is not proportional to the duration of
attitude.

Glass is not a liquid per se, as in not just a very high viscosity fluid, it
is a
super cooled liquid. Also known as an anamorphic solid. This state or
phase of matter is reached by cooling a fluid at an extremely high rate
(relatively to the materials normal freezing characteristics).

Even metal has been rapid frozen into an anamorphic solid 'glass' state
and if cooled slowly enough, glass will cool in to the crystallized state
more
common in metals and most other solids. This crystallization is known as
devitrification. It just turns out that molten glass is the only readily
available
liquid that has a high enough and shallow enough knee on the melting point
curve that is easily super coolable.

There are types of matter that have been artificially held in the super
cooled
liquid state. Because glass is the first, best known example, these states
are referred to as a glassuous state.

Hope this helps.

-G


_________________________________________________________
Do You Yahoo!?
Get your free @... address at http://mail.yahoo.com