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 end ************************************************** 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] **************************************************