Re: [ATM] Pyrex Quality Suffering

[artbianconi@blast.net]

The 15" I am working on was fine annealed by Newport to relieve any 
internal stresses. Wonder where they bought the glass.

Of course you are right about my inappropriate use of the word 
"tempered". Thanks for pointing that out. The stresses within your 
typical tempered glass are enormous. Such stresses would eventually 
distort even the most precise figuring


If our mirrors were tempered, as I suggested, they'd shatter in 
thousands of tiny pieces at the slightest chip, which is one reason 
who DOT requires laminated safety glass on the front windshields of 
cars. 

Art Bianconi

On Sun, 21 Mar 2004 artbianconi@blast.net wrote:

> I went on a 3 day weekend with some bikers last year to Wellsboro,
> PA. (just 20 miles east of Cherry Springs State Park.)
>
> There aren't many jobs to be had out there and the nearest employer
> of an consequence, Corning Glass works (2 hours north), was rumored
> to have laid off 3000 employees.
>
> This year, Steve Swazie again supported the DelMarva groups Mirror
> Making  event in Delaware. I heard him share his opinion that the
> quality of Pyrex has suffered ever since Corning shut down it's New
> York operation and moved it to England.
>
> The name "Pyrex" is a copyrighted trademark for Corning's brand of
> tempered glass. They are far from being the only supplier of such
> glass and I have noticed many call their glass Pyrex, even when
> there is reason to suspect that it may be someone elses glass.
>
> What I know about glass I can put into a shot glass and still have
> room for a gallon of Pepsi. One thing is clear however (sic!), the
> times they are a changin'.
>
> The assumptions we are used to making about the quality and
> predictable behavior of tempered glass, Pyrex especially, may no
> longer be justified. I am not sure if we should be concerned about
> this or not.
>
> Art Bianconi

Ages ago, 1970's, some suppliers took the Corning blanks and
re-annealed them for the telescope trade.  (If my memory serves me). 
Perhaps this will start up again.

Hmmm.  Dunno about a Corning layoff north of Wellsboro, but there was
a big hit in Altoona, (about 2+ hrs south) at a works that made
television picture tubes.  Shut the plant, sold the machinery to the
Chinese.  *poof*

Nit-pick -- Pyrex isn't tempered, it just has a low thermal expansion
coefficient, so it can, in sections somewhat thicker than regular 
soda glass, take thermal shock without cracking.  I believe Pyrex is 
a "borosilicate" glass.

Dave



_______________________________________________
ATM mailing list http://www.atmlist.net/