Paintings mounted on sheet metal

For an environmental improvements project, I am trying to understand
the installation system that was used during the 19th century when
large paintings were installed in a large public building.  What we
do know is that the paintings are on   canvas and were installed on
sheet metal. As the paintings are in an upper story of a rotunda in
a cove wall area, I am unable to get examine the surface of the
paintings, except with binoculars. I can get behind the paintings in
an interstitial to closely examine the back side of the installation
.

>From what I can see, there are tacks (actually nails) that extend
through the canvases to the backside of the sheet metal.  The heads
of the tacks/nails are visible on the face of the painting. Also
visible on the face of the paintings are:

    Large areas where the canvases appear to have delaminated from
    the substrate sheet metal - these appear as large "bulges"

    The seams of the sheet metal - these don't appear to have
    penetrated through the canvas

    Possible surface bloom

The owner's files are very limited. We haven't found any
documentation concerning the installation of the paintings. We do
know that the artist lived in another part of the country and there
is no record of travel to this area to install the paintings. The
paintings may have been installed by the painter hired at the time
to decorate other areas of the building. There is a brief
conservation treatment report from several decades ago when the
paintings were treated during part of a building renovation.  The
report mentions that in addition to cleaning and in-painting losses,
there were areas that had been reattached to the metal substrate
through adhesive injection.

Does anyone have any information on adhesive systems that were used
in the 19th century to attach canvas paintings to architectural
metal?

Wendy Claire Jessup
Conservator
Wendy Jessup and Associates, Inc.
933 N. Kenmore Street, Suite 323
Arlington VA 22201
703-522-2801


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                  Conservation DistList Instance 29:40
                   Distributed: Sunday, March 6, 2016
                       Message Id: cdl-29-40-022
                                  ***