Consolidating plaster of Paris sculptures

I am a paintings conservator, posting this query on behalf of
Estelle, historian to the Voortrekker Museum, Pietermaritzburg.
Unfortunately we do not have an objects conservator in the province,
so we would be most grateful for any advise. The treatment would
therefore also have to be carried out by myself, a qualified
paintings conservator.

The query is with regards to plaster of Paris casts. The collection
of sculptures is from the Stainbank Collection.

Estelle writes of the collection: The collection of sculptures
contains busts which were cast in plaster of Paris, some moulds, and
cast relief panels. Some of the busts have been painted with what
seems to be a water-based acrylic paint. These works seem to be
stable. However, some of the unpainted busts have been exposed to
water while they were in storage in the artist's studio and I am
concerned about their conservation. The outer layer of these casts
appears to be thick and smooth, but the plaster itself seems quite
soft and where there is damage, the inside is quite porous and full
of bubbles. The room where these sculptures are on display has no
air-conditioning, but the windows have been sealed and the humidity
levels and temperature are within the range suitable for South
African museums. Yet, there is some dust, and the sculptures are
dusted on a weekly basis. How can plaster of Paris works be
conserved adequately? Is there any substance that can be painted
onto works to prevent further damage?

Having seen the works myself, my greatest concern is those works
which have been exposed to water dripping on them in the past. The
water drips have eaten away cavities, leaving a bubbled,
glacier-looking cavity. These cavities are crumbling and weakening
the sculptures. I would like to know whether there is a way of
consolidating these plaster casts, perhaps by injection or
impregnation. Conservation materials are not always easily available
to us here in South Africa, but we would have access to any of the
solvents, adhesives, waxes, resins etc. used in painting
conservation treatments. We would appreciate any advice.

Lucy Campbell-Ker
Paintings conservator
Durban Art Gallery
South Africa
+27 31 337 5435
Fax: +27 31 368 3093


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                  Conservation DistList Instance 14:15
                 Distributed: Thursday, August 24, 2000
                       Message Id: cdl-14-15-011
                                  ***