Gesso

Birgitte Speake <birgitte.speake [at] pitt-rivers-museum__oxford__ac__uk>
writes

>Does anyone have any experience with securing lifting gesso and
>paint layers back onto a wooden substrate.  We have a number of
>wooden masks with large (1-2cm square) areas of lifting gesso. The
>gap between the lifted layer and the wood is in places as wide as
>2mm making simple consolidation inappropriate.

Our experience with ethnographic and ancient Egyptian polychrome
wood has shown that a solution of Paraloid (Acryloid in the US) B72
in acetone, applied as a consolidant, acts as an intermolecular
lubricant for some time after the surface is touch dry, while the
body of the gesso/paint is still filled with solvent. During this
period a considerable amount of reshaping (with great care) can be
done which may allow some lifting surfaces to be relaid. If the
lifting surface is larger than the substrate (because of shrinkage
of the substrate) a gap-fill to support the paint/gesso may be more
appropriate. In this case a viscous solution of Paraloid B72 mixed
with aerated silica or glass microballoons has proved effective. See
Jaeschke, R.L. "A method of reshaping cartonnage without water." in
Proc of 2nd Conference on Conservation of Ancient Egyptian Materials
1995, published 1996 by Archetype Publications. Hope this helps,

Richard and Helena Jaeschke
Archaeological conservators


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                  Conservation DistList Instance 16:24
               Distributed: Thursday, September 26, 2002
                       Message Id: cdl-16-24-007
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