Removing UV-filtering film from historic glass

Approximately 10 years ago, a client of mine installed UV film on
the glass of one of their 18th-century buildings.  At the present
time, and as noted in a General Conservation Assessment conducted in
1991, the adhesion of the film on some of the lights has failed and
there is lots of evidence of bubbling and film pull-off.  The
assessor in 1991 recommended replacing the film and the client began
a program to replace it but found that they were breaking glass.
They've asked me to inquire if anyone has any suggestions.

I have recommended that they conduct a complete window by window,
light by light, inventory of the efficacy of the film (they have a
UV monitor which is functioning properly) and document which ones
have failed either in UV filtration and/or film adhesion.  Then, we
can work to replace UV filtering on the windows where we know the
film has failed.  We are looking at the installation of interior
storms fabricated of UV filtering sheet goods, however we need to
assess the impact on the historic sash. Anyone developed any tricks
for safe removal of the film that has partially lost its adhesion on
18th century glass?  Thanks,

Wendy Claire Jessup
Wendy Jessup and Associates, Inc.
210 Little Falls Street, Suite 203
Falls Church, Virginia  22046
703-532-0788
Fax: 703-532-1661

                                  ***
                  Conservation DistList Instance 10:13
                  Distributed: Thursday, July 25, 1996
                       Message Id: cdl-10-13-007
                                  ***