Re: ATM Annealing Pyrex

["Brian L. Nestel" <blast@aloha.net>]

Tim Walters wrote:
> Hi All,
> I just spoke at length with a gentleman in Atlanta that's been producing
> laboratory glassware (Pyrex) for close to 40 years. He says the way he
> anneals Pyrex is to bring it up to 600 C and let it "soak" FOR 10
> MINUTES and let it cool off gradually FOR 3 HOURS. I always assumed it
> took days/weeks to anneal "stuff". He checks all his glassware with a
> polarimeter and he says -NO- stress is evident.
Lab glassware is alot thinner than a mirror, the ammount of time that
it takes to anneal pyrex properly depends on the thickness, a large
thick
mirror is going to take alot longer. Check the archives, Richard
Swarthz the resident expert has made many posts on the subject, 
or contact him direct.

> 1) Do you anneal Pyrex before or after you grind it?
before. 
> 2) Which would you rather make/have?:
>     a) 14" dia., 1 1/2" thick mirror
>     b) 16" dia., 1 1/4" thick mirror
1 1/4 is not too thin, think aperture, any extra photons count.


-- 
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Brian   Middle of the Pacific,
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