[ATM] BVC material properties

[George Anderson]

Mark Holm wrote:
> Tom Krajci wrote:
>>> From: George Anderson <tillerman1 at videotron.ca>
> 
>>> The mirror blanks are made from layers of BVC that are fused together.
> 
> According to Andre, also on this list several years ago (as I recall),
> the glass does not come from Pilkington in the BVC form.  He does indeed
> fuse stacks of sheets together.  In the fusing process, he also uses the
> heat to modify the glass micro structure, producing the BVC product from
> a starting material that was glassy and (probably) transparent.  At
> least one list member has attributed this transformation to
> "devitrification", a phenomenon in which prolonged heating at the right
> temperature causes crystals to precipitate in some glass compositions.
> 

Hi Mark

I remember Andre on the list having to defend his product. At one point 
he was referring to a "secret glass" from Pilkington. I guess that changed.
Interesting the theory about the devitrification, since the official 
name for BVC is "Black Vitrified Ceramic".

George Anderson
Montreal Canada

Clear skies and good health