Objects Specialty Group – Wednesday, May 12, 2010 – Cont.

3:00 – 3:30 p.m. Plaster, Pliacré®, and Paper

Mina Thompson and Conor McMahon, Associate Conservators, Museum Resources Division, Department of Cultural Affairs, New Mexico

Mina Thompson gave this talk about the history of conservation in the Museum of New Mexico System, focusing on archaeological ceramics and Spanish Colonial Santos as examples of artifacts who’s retreatment and reexamination have influenced choices made in recent years toward less toxic and more easily reversible treatments.

The Mimbres ceramics in the Museum’s collection had suffered under previous treatments which resulted in extensive staining and discoloration. These disfiguring stains prevented accurate reading of the ceramic vessel’s illustrations and designs. Research revealed the previous treatments included coating/consolidation with cellulose nitrate and Plaster of Paris fills. Joint masking was achieved through natural resins and polyvinyl acetate resin. Linseed oil-based overpaint had been used to tone the fills. The staining appeared to be a result of oil absorption into the ceramic body.

An ammonium bicarbonate poultice applied over a mulberry tissue interleaf was used to reduce the staining. Removal of the stains and coatings revealed paint polish strokes, use-wear marks, and in some cases previously filled kill holes in the base of the vessel. Other plaster fills were left in, as they provided structural support; they were toned with acrylic paints. Where additional structural fills were needed, Pliacré® epoxy was used.

The second collection type examined were Spanish Colonial Santos. In 1952 the Museum hired Elizabeth Boyd, an artist/restorer, as the Curator of Spanish Colonial Art. It was E. Boyd who contacted Gettens in the 50s for help with Spanish pigment identification. The carved and painted Santos that Boyd focused her research exhibit numerous areas of wear and paint loss, some of which is quite distracting. Losses were masked by creating mulberry tissue fills toned with acrylic and tacked at the edges of the loss using methylcellulose. This covered the exposed gesso with a completely removable fill. [blogger’s note: post-talk comments revealed that this technique has been written/presented by P. Hatchfield and M. Maricolo and is available in previous AIC post-prints (year uncertain) – successful tissue fills have been made on stone, wood sculptures, and ceramics]

The Museum of New Mexico’s continuing goals for conservation are to make knowledge about treatments available for shared collections, so that other institutions with similar collections/problems can benefit from their knowledge. They are also very interested in the idea of a database of early conservators with archival documents and images.