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Subject: Window films

Window films

From: Robert L. Self <bself>
Date: Friday, September 27, 2002
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?

I'd like to respond with some specific information supplementing an
earlier comment about the shade material in use at Monticello.

We currently have tinted shade material suspended in front of the
windows from the inside by means of spring tension rods at the top
and the bottom.  They are not actually roller shades per se. These
shades have been in place since 1993. They screen out 99% of UV and
although specifiedd to filter out 90% of visible light, measurements
have indicated that 85% is more like it. The material is
manufactured by C.P. Films in Martinsville, Virginia. The specific
product is RS-10 B/B.  It is a metallic laminate rather than a dyed
material and is thus not as susceptible to fading as the dyed films
are.  In some locations on the northeast side, we have upped visible
light transmission by using a different material which takes out
65%. For these we have had to use a thinner film product rather than
the thicker shade material because the shade material is only
available in denser, darker grades.  We have had to replace the
shades once since they were initially installed due to decreased
effectiveness at filtering UV.

We have found this solution to be a simple, effective, low-tech
solution for solar filtering.  However, as noted by John Horton,
they are not ideal from the visual standpoint.  They have a rippled,
reflective appearance from the outside during the daytime.  At night
the effect is reversed and it is from the inside that they are the
most distracting. The thinner film material suspended in front of
some windows is particularly noticeable.  There have been many
complaints about the appearance of these solar shades.  Although
there is probably no perfect solution, we are once again in the
process of exploring other options which might be less of a
compromise visually- specifically rigid acrylic sheet (Plexi) which,
although still unavoidably dark in appearance, lacks the rippled
effect of the shade material. Films applied directly to the glass is
not being considered for reasons already noted by others on this
topic. We are also exploring the possibility of incorporating solar
filtering into a supplemental glazing system ("storm windows")as a
means of also combatting window condensation which is a serious
problem during the cold months even at lowered temperature and RH
setpoints.  This, of course, represents an entirely new thread
which I would welcome discussion on but which is not really part of
the current topic.

Robert L. Self
Architectural Conservator

                  Conservation DistList Instance 16:25
                Distributed: Wednesday, October 2, 2002
                       Message Id: cdl-16-25-004
Received on Friday, 27 September, 2002

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