Plaster casts

John E. Simmons <jsimmons [at] ku__edu> writes

>I am looking for (1) any conservators with expertise in the
>preservation, repair, restoration of plaster casts; and (2)
>references in the literature to the preservation, repair, and
>restoration of plaster casts.  The casts in question are 19th
>century casts of classical statuary and friezes.

In the past months I have carried out some cleaning tests on plaster
casts of classical statuary. A gel of 4 to 5% Laponite RD and 5%
Acematt (Aerosil) in deionised water worked very well. However, the
gel won't have the same good cleaning effect on plaster coated with
paint.The recipe is from a German article on the cleaning of plaster
casts. There is also a dissertation on plaster in German.
Unfortunately, I haven't come across any literature in English in my
limited search.

I also tried the old technique of removing dust with Agar, but found
that residues from the gel are an ideal "feeding ground" for mold.
Laser cleaning will also give good results, but at a wavelength of
1064 nm the plaster (or dirt on its surface) turns yellowish brown.

Regarding repair I have so far used Paraloid B 72 for adhering
broken off pieces, and plaster for small repairs. A colleague of
mine recommends "Keramiplast", which is a ceramic-like, air-drying
material.

Jorun Rebekka Ruppel
Archaeological Institute
Goettingen, Germany


                                  ***
                  Conservation DistList Instance 17:33
                 Distributed: Tuesday, October 7, 2003
                       Message Id: cdl-17-33-003
                                  ***