Specifications for glazing

The chief danger of using the laminate is that it will turn out that
the level of visible light filtration will not be high enough, and
that someone will want to suggest that further filtration with
sheets of tinted Plexi be added.  This will not be a happy day,
given the expense.  We have found that many historic houses can
tolerate a rather high level of gray or bronze Plexiglas for
filtration and that it actually aids viewing because in many houses
visitors look directly at the windows when viewing the rooms.
Interior lighting then has to be added, of course.  I don't know the
set-up of the space that is being redone, but I would suggest some
serious tests using different grades of Plexiglas to make sure that
the decision is correct.  One requirement for successful uses of
visible filtration is that the viewers not see any bright source
even out of the corner of their eyes, so even tests have to be
controlled carefully for contrast.

B. Appelbaum

                                  ***
                  Conservation DistList Instance 12:4
                  Distributed: Thursday, June 18, 1998
                        Message Id: cdl-12-4-012
                                  ***