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. My question to the list is, does anyone know if there is a standard life for them (say 5 years as Light Impressions says), or if the lifetime differs based on the manufacturing process? University Products tells me that their filters will last indefinitely, does this ring true? Thanks for any responses, Cris Wolf Harper Collections Manager UIHC Medical Museum 8024A JCP/200 Hawkins Dr. Iowa City, IA 52242 (319) 356-8475 FAX (319) 356-3862 [log in to unmask]