Re: [ATM] Does exposed Pyrex lose polish over time?

[Thomas A Simmons <tasimmons@raytheon.com>]

Virgil,

  Apples to oranges. Perhaps your experience gives evidence
to the article on Mel's web page that polishing is as much a
chemical reaction as it is a planing of the glass?

  In effect, isn't this a long duration contact of pyrex in a very
thin polishing slurry?

Tom
Tucson, AZ

Date: Thu, 6 May 2004 15:08:44 EDT
From: Raidoflostdark@aol.com
Subject: Re: [ATM] Does exposed Pyrex lose polish over time?
To: toolontop@yahoo.com, atm@atmlist.net
Message-ID: <1e6.1f6ee839.2dcbe73c@aol.com>
Content-Type: text/plain; charset="US-ASCII"

I had an enteresting experience with a piece of pyrex once. I was in the
figureing stage of a 6" mirror that I had been placing face down on a paper
towel
that was laid ontop of a plastic coffeee can lid. I was kind of fond of
this
storage method because the mirror fit into the lid and paper towel so well.
I
liked the way the lip on the lid seemed to protect the edge of the mirror.

I had no problem until I was in a hurry once and put the mirror onto the
towel slightly damp.  Next day on the tester, there appeared  a very narrow

circular zone that perfectly matched the diameter of the raised center area
of the
lid.  This was the radius where the contact on the surface was. Washing
couldn't touch it. It took about 1/2 hour to polish it out.

This was an early mirror where figureing was all over the board and back.
It
had been polished out weeks before this occured!.

Virgil Johnson
Raider of the Lost Dark

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