Re: [ATM] Does glass retain moisture?

["Mel Bartels" <mbartels@bbastrodesigns.com>]

changes a tiny bit after the mirror as a whole equilibrates to a different
temperature. Given that, why do some people with mirrors of very high
quality claim that the star test is different at warm temperatures than at
cold temperatures?? (Of course, I'm talking about AFTER the mirror has
equilibrated to the ambient temp. We are fully aware that the star test is
horrible AS the mirror equilibrates.)

You can see this effect in average to poor quality mirrors.  It's simply due
to the unequal cooling of the glass, that is, the front of the glass cools
at a different rate than the back portion of the glass.  Plate glass has it
worse than pyrex.

Mel Bartels

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