Regular picture framing glass filters about 49% of the UV. As fdi has indicated that UV glass such as TruVue Conservation glass filters 97% of the UV and the Cyro Acrylite (Plexiglass) filters 98% of the UV. To avoid some of the issues of scratching the Acrylite that Scott has mentioned, Cyro makes the AR OP3 -abrasive resistant, optically pure (3) which is abrasively resistant. But it is very expensive; but it does scratch and it is a static magnet. I normally use glass up to 32" X 40" in size. You will have better luck using glass in wooden frames rather than metal because the wood will absorb, while the metal transmits shocks.
My wife did some artwork using acrylic painting on acrylic - and only uses canned air to clean as she doesn't trust any sort of wiping for cleaning. Seems to work OK, too.
B & D Rochester, NY
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