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[ATM] convex secondary

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Subject: [ATM] convex secondary
From: "Greg Jones" <gregj888@comcast.net>
Date: Fri, 11 Mar 2005 23:18:18 -0800
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 "Pyrex is not homogenous and has a lot of fine grain boundaries.."

I've read this in all the old texts too but am wondering if it's true (or still true).  Has anyone checked a Pyrex blank in the last 10 yrs?  Seems like to be low expansion it would need to be homogeneous, and how do you make it so it is not?  Has to be annealed too.  I'm not saying it's any better now than 40 yrs ago, just suspicious.

It's on my "to do list" to check, but still a ways from the top.


Greg Jones
http://home.comcast.net/~dac20/dac_001.htm

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