Pat et al., I got some additional information on UV Plexi from our house curator. The plexiglas is 1/8" UF3 or OP2 plexi. The manufacturer doesn't matter as much as the rating. We also use flexible plexiglas coverings for the one flourescent fixture in the house. The curator chose the flexible plexi because it can be easily cut to size and slipped over bulbs without taking them out, and can be easily switched when the bulbs are changed. They were also installed in the fixtures in our registrar's office, where they were apparently double layed because of the excessive number of lights. The UV meter is a Crawford meter, and costs $1,200. We bought ours from Art Preservation Services in New York City (539 E. 81st St, NYC, NY 10028, fax 212-794-3045). Leslie Johnston Historic New Orleans Collection [log in to unmask]