Fluorescent tubes and UV

Gregor Trinkaus-Randall <gtrinkaus-randall<-a t->state< . >ma< . >us> writes

>Most of these institutions are lit with fluorescent tubes.  Most
>also do not have UV-filtering sleeves on these tubes.  However, many
>of them, the tubes that is, are located above the plastic shields
>that cover the bottom of the "boxes" in which the tubes are housed.
>Even so, I expected to get high UV readings below these lights. Much
>to my surprise, the readings are low - around 10uM/lumen or 2-3
>uM/M2.

In the CAP surveys I have done at small museums, plastic light
covers seem to provide UV filtering, even if the bulbs are not
screened.  I read (and can not find the source, now) that different
types of plastic films have different energy absorbing capabilities.
Thus, a polycarbonate clear light cover may absorb UV energy
readily, while a polyester covering would not without special
additives.  Before spending money on UV sleeves, I have been
recommending that museums test the UV levels of fluorescent lights
with plastic covers first.

In reference to the library with windows:  UV light *and* visible
light will damage the collection.  In a case like this I usually
recommend curtains and shades, they eliminate both.  The UV
filtering alone will not completely protect your collection.

Helen Alten
Field Services Director
The Upper Midwest Conservation Association

                                  ***
                  Conservation DistList Instance 10:62
                 Distributed: Friday, January 10, 1997
                       Message Id: cdl-10-62-003
                                  ***