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Subject: UV filtering materials

UV filtering materials

From: Niccolo Caldararo <caldararo<-a>
Date: Saturday, July 16, 2005
In response to Joachim Huber on UV filtering materials. Here is a
lesson in relying on technical data. In the early 1980s Bob
Futernick asked me to acquire data on the UV filtering properties of
different materials on the market as the Fine Arts Museums of San
Francisco was investigating reducing light from the windows and
skylights. I contacted the available vendors and manufacturers and
received their reports. I received a variety of responses from
manufacturers about the longevity and effectiveness of the UV
absorbing or blocking agents. Garry Thomson  in his Museum
Environment (1978) related that the various plexi glass formulations
like UF-3 had a life of 10 years, the manufacturers often argued
that there was no reduction at all over time. Lexan was supposed to
be much longer lived according to the vendors. Instead of taking
this information at face value, Bob did UV transmission tests
himself and was very dissatisfied by the results.

There are a number of factors to consider, tints, the films and
their adhesives, Titanium dioxide paint. We eventually took the
latter route as it seemed the most durable and cost effective.
Things may have changed, and the various products improved. I do not
know. I have a copy of Bob's report but it was an internal document.
You might want to talk to him to find out if his testing results are
still valid.

Niccolo Caldararo
Conservation Art Service

                  Conservation DistList Instance 19:6
                   Distributed: Sunday, July 17, 2005
                        Message Id: cdl-19-6-009
Received on Saturday, 16 July, 2005

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