Chris, We have tried to figure out the same thing; none of the vendors we have spoken to know the shelf-life of the UV filter tube; we have been told these things work indefinitely, blocking UV waves. At the same time, it kind of depends on how long the lights are left on in your storage and exhibit areas. Perhaps the thing to do is to set up a policy whereby you switch the tubes out at a certain time, let's say 5 years for exhibits and ten years or longer for the storage spaces. There's a little booklet out there that addresses UV in its quantifiable nanometers. Something about staying between 400 nm and 700 nm. If you have a UV meter you can take a reading and see if you are between those acceptable nm's. Just to be on the safe side we always frame with UV glazing and our plex tops are UV filtered. O Olivia S. Anastasiadis, Curator Richard Nixon Library & Birthplace 18001 Yorba Linda Boulevard Yorba Linda, CA 92886 (714) 993-5075; fax (714) 528-0544; e-mail: [log in to unmask] On Wed, 2 Jul 1997 13:53:19 -0500 Christine Wolf <[log in to unmask]> writes: >Hello all, > >I'm trying to determine how long UV florescent light filters last >before >they should be replaced. I've called several archival companies that >sell >these filters and have gotten different answers.....