I've posted this before and hope I'm not boring everyone.

Using an excellent and expensive Crawford UV meter and testing a whole
line-up of gliders one day there was a distinct pattern of older
gliders passing UV and newer gliders not. Eric, one of these days
I'll be out at EPH the same time as you are and we can do some
research on the line-up out there, but we won't get wavelength charts

My sense of this issue is that higher quality plastics have more
chemicals in them to protect the plastic itself from UV damage and
that it is protecting us as an unintended consequence. Most plastics
used in the lighting industry are very good UV filters, for example
the lenses on under cabinet fluorescent fixtures usually are very good
even on the cheapest fixtures. On the other hand there is a very
nice, small German under cabinet fluorescent (Hera) that I used to
light part of a rare book collection and ended up having to add UV
film. UV film is cheap so it was no big deal.


Brian