Ultraviolet filtering window glass

A question about the length of time ultraviolet filtering in glass is
effective.  UV filtering glass has been recommended for our renovated
Special Collections reading rooms.  Most of the literature I've
consulted indicates that effectiveness is 10 to 30 years.  I doubt glass
will be replaced after 30 years (unless I intentionally break it).

Alternately, translucent or opaque glass with smooth outside surface
and cockled/rippled/fretted inside surface has been proposed.  The
smooth opaque outside surface for reflectance; the cockled inside to
refract and diffuse UV ... similar to the effect produced by fluorescent
light fixture screens.  I am inclined to support the latter. Anyone seen
any literature on the subject lately?

Erich J. Kesse.

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                  Conservation DistList Instance 5:57
                   Distributed: Sunday, May 17, 1992
                        Message Id: cdl-5-57-007
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