African stool

William Low <wlow [at] abacus__bates__edu> writes

>... The stool
>is African (specific origin unknown--possibly Cameroon) ...
>... We
>recently noticed white, powdery looking substance on the underside
>of the stool and supporting figures. Older condition reports list
>"white accretions" on parts of the piece. ...
>...
>While this does not appear to be a bloom, I don't want to rule it
>out.

The condition described on the African stool may be fatty bloom
which is commonly found on African wooden objects.  It is
characterized by the formation of a thin layer of fine, clear-white
crystals.  Fatty bloom is caused by the ethnographic application of
fats/waxes, commonly shea butter, to the surface of the wood.  In
hotter climates, like many regions of Africa, they do not
crystallize; however, in cooler climates--including
climate-controlled museum storage and exhibition areas--crystals
form on the surface.  Our museum has numerous objects with this
condition,  which is not thought to be harmful to the artifacts.
When the objects are displayed, upon curatorial request, we
sometimes remove the bloom by swabbing the area with dry swabs for
mechanical removal or with xylene or naphtha-moistened swabs.  This
treatment is temporary and the condition will return as more of the
fatty substance solidifies.

A thorough discussion of the subject can be found in Ellen
Pearlsteins's article "Fatty Bloom on Wood Sculpture from Mali,"
Symposium 86: The Care and Preservation of Ethnological Materials,
Proceedings, ed. R. Barclay et al., Canadian Conservation Institute,
130-136.

Stephanie Hornbeck
Objects Conservator
National Museum of African Art
Smithsonian Institution


                                  ***
                  Conservation DistList Instance 15:15
                 Distributed: Wednesday, August 8, 2001
                       Message Id: cdl-15-15-012
                                  ***