----- Original Message -----
From: "Don Cox" <[log in to unmask]>
> > Yes, they're playable but even glass changes shape over time.
> I saw an exhibition of Roman glass a few years ago. Those bottles etc
> didn't show any signs of having changed shape over 2000 years.
Well, glass is technically a liquid (as is the shellac compound used to
press 78's). It does not have a crystalline structure, as do solids.
It's my understanding that very old window panes are marginally wider
at the bottom, exhibiting proof that the component material has flowed
over the centuries...
(whose physique has noticeably flowed over the past decades...)