I am not a fan of tinted or UV films applied directly to windowpanes. Many
degrade after 8 years or so and the tinting fades away even sooner,
especially in south windows. They are difficult to remove and for that
reason should not be applied to old glass windows of hsitoric houses. 

For blocking UV and visible light, I always recommend more permanent
interior storm windows made of either tinted UV-filtering UF-3 Plexi or
tinted Lexan (polycarbonate). The Lexan is less expensive but more prone to
scratching. The Plexi filters more of the UV (97% vs 92%) and remains
clearer longer, as Lexan can tend to "gray" over a few decades. Both
products are special-order and can be obtained in various tintings. I like
the bronze tint because it gives a warmer view than the gray. Both can be
obtained in tints of 30%, 50%, 75%, 90% and 99%. One can hardly notice the
30% and 50% tints and can still view outside surprisingly well through 90%,
although it does look like a dark day as you view outside. Go online to find
distributors in your area and request samples of the various tintings. I
purchase scraps of at least one square foot since it is hard to get a good
idea looking through the small 2" x 2" samples usually provided.

In addition to filtering the visible and UV light, interior storm windows
also save energy by improve the tightness of the window units and prevent
condensation on the glass windows during the winter in cold climates. If
properly installed, they increase security by making the windows more
difficult to penetrate, especially if 3/8" or 1/2" Lexan is used. We mount
the plastic sheets between two strips of wood molding attached to all four
sides of the inside of the window frame. A silicon p-gasket is installed
between the window side of the Plexi and the inner wood molding to prevent
moisture from a humidified gallery from seeping between the windows.

We have installed this type of interior storm windows in 7 of our collection
buildings and are very pleased with their performance. Both IMLS and NEH
grants have supported the purchase and installation of interior storm
windows to improve the interior environments for the collections. Contact me
off list if you want more details. 

Richard L. Kerschner
Director of Preservation and Conservation
Shelburne Museum
(802) 985-3346  x3361

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