Mold on wax resin lined paintings

I am writing for advice on remediation treatment of mold found to be
present on the lining support of a wax-resin lined painting.  This
painting is one of many from a museum collection.  The collection
was treated over 40 years ago; all the paintings were removed from
original stretchers, lined with a single fiberglass lining infused
with a wax-resin adhesive.  Upon removal of a 40 year old plus
pressboard backing on one of the paintings that was in the studio
for treatment, a strong odor of mold/mildew was detected.

A state licensed  mold firm was contacted to test for the presence
of mold. The backing test was negligible (although the backing
tested for a high moisture content); however, the swab test on the
back of the lining (a single layer of fiberglass infused with
wax-resin adhesive) tested in a high range for two types of mold
(cladosporium and aspergillus with a prevalence score of 5 for
extensive).

The museum environment and storage area is controlled at 50% rH.  I
gently swabbed the back of the lining with xylene in one area,
naphtha in another area and mineral spirits in a third area.  The
swabs were yellow. I am going to have the painting re-tested in
these areas as well as under the stretcher bar to see if the mold
has been reduced significantly and test for the presence of mold
under the stretcher bar).

I am writing for suggestions on how to proceed with this problem.
The backing can be removed and simply left off as it is trapping
moisture behind the painting.  The rH can be lowered in the
museum/storage area.  However, if the wax-resin is the "host" for
the mold there is not much we can do but remove it as safely
possible from the back and stretcher, etc. and control the
environment.

Is there something else that should be done to solve/manage this
problem?  I would greatly appreciate any suggestions you might
offer.  Thanks so much,

Helen A. Houp
Conservator
2626 Lombardy Lane, Suite 106
Dallas, TX  75220
214-366-4700
Fax: 214-366-4740


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                  Conservation DistList Instance 22:55
                  Distributed: Friday, March 27, 2009
                       Message Id: cdl-22-55-018
                                  ***