It seems to me I was once told that some glass was transparent to UV at one
point in it life but that quickly changed. I also think it was transparent
at the start and become more opaque over time (a relatively short time
too.) If this is true (and I am really stretching my memory) then a plastic
film that failed after a few years would be alright behind a glass that had
by then become opaque by then. I also think that the specral curves, shown
in glass catalogs, are drawn right after the glass comes out of that pot. I
also suspect that for glazing material they are most concerned about the
visual end of the spectrum. I'll also bet those rascals at the Corning
Company in Corning, New York know all about such things.

END
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Douglas W. St.Clair
Tir Na Nog
400 Burton Highway
Wilton. NH 03086-5022
PH: 603-654-9321
FAX: 603-654-5440
EMAIL: [log in to unmask]
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