Window films

Monica Dean <mdean [at] mollybrown__org> writes

>I have been reading the archives, and wondered if there were any
>different feelings on this subject since 1999.  I am the Curator of
>Collections at the Molly Brown House Museum in Denver, CO.  We have
>had UV filtering Plexi on our windows since the late '80s, and it is
>time for it to be replaced.  We are in the process of researching
>whether to replace the Plexi again with Plexi or to try the UV film.
>The reason I am attracted to the film is that it also blocks out
>heat (a major problem here in the summer time).  However, the
>windows are historic, and I have heard all of the horror stories
>about windows breaking when film removal was attempted.  Does anyone
>know of anything new on the market that is easier to remove, or are
>we safest staying with the Plexiglas?

Is the Plexiglas also serving as an interior storm window so that
the heat build-up in the cavity between the window and the Plexiglas
is a concern? If you were to put film on the historic glass, would
you still have a need for a storm window?

There is only one museum house in my region that has used film--Fort
Defiance in Happy Valley, NC (ca. 1790). The only problem I have
heard of is sloppy application which leads to wrinkles and bubbles,
so they have had to redo some windows. The old glass is so irregular
that the application of a film is never ideal. Of course, cleaning
the film is also a housekeeping issue since it is easily damaged. If
you wish to contact the site manager send me an email and I will
forward the contact info.

Another museum house--Quaker Meadows in Morganton, NC (ca.
1812)--used interior glass panels with a UV coating, so they double
as storm panels to some extent. However, there is ventilation top
and bottom to prevent heat build up. (Unfortunately these gaps let
bugs and dirt in also--a constant housekeeping issue).

I recall that Monticello uses a film in the form of roller shades
that hang loose in front of the windows. Although this may be a bit
visually distracting, the obvious advantages are 1) minimal
intervention to the historic fabric; 2) ease of housekeeping; 3) no
risk of heat or moisture build up in the cavity.

If a panel is decided upon, you might consider using a UV resistant
laminated glass instead of Plexiglass. The laminated glass would be
resistant to warping from any heat build up in the cavity, and would
be less trouble to clean. An important detail to consider either way
is how to ventilate the cavity to avoid potential condensation.

John Horton, RA
Restoration Specialist
NC State Historic Preservation Office
Western Office - Archives and History
1 Village Lane, Suite 3, Biltmore Village
Asheville, NC 28803
828-274-6789
Fax: 828-274-6995


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                  Conservation DistList Instance 16:22
                Distributed: Friday, September 20, 2002
                       Message Id: cdl-16-22-004
                                  ***