Plexiglass support for canvas paintings

On behalf of a client of mine I would like to pose his question (to
me) to other paintings conservators in the conservation community.

   "I have a Mendjisky, a French artist. The painting is probably
    about 30-40 years old, and it has been worked on by a
    conservator in Houston. (His contact information is on the back
    of the painting). For reasons unknown to me, perhaps valid, the
    canvas was adhered to plexiglass. The painting is worth about
    $40,000 so I need to make sure it was restored correctly."

Please comment on the use, advantages /disadvantages and/or practice
of using Plexiglas as a rigid support for paintings.

Dennis Baltuskonis
Art Conservation Services
San Antonio, TX


                                  ***
                  Conservation DistList Instance 20:26
                 Distributed: Monday, November 13, 2006
                       Message Id: cdl-20-26-019
                                  ***