Should a Conservationist Irradiate a Wax Sculpture to Repair It?

by Matt Fleischman

Since 1927, a tinted wax sculpture of Anna Pavlova wearing a decorative Russian headdress has been in the Carnegie Museum of Art collection, but early damage resulted in cracks so severe that the piece has not been exhibited in decades. A copy of the original 1924 portrait at The Metropolitan Museum of Art, the Carnegie's sculpture is in the museum's conservation lab, where I am formulating a method to repair it. An extremely delicate medium, wax was used by artist Malvina Hoffman to "catch some of Pavlova's fantastic lightness and grace."

To construct the portrait of her dancer friend, the artist made a plaster mould directly from the subject's face. From this Hoffman modeled a positive form in clay, which she then refined. She then made a mould from the clay portrait and built up layers of wax within the mould. After layers of wax had been applied, the fragile wax shell was filled with plaster. A round brass rod was mounted into the plaster as it dried, allowing the sculpture to rest securely atop its base. Finally, the surface was embellished with pigments.

The sculpture is cracked on the front, back and sides, all of which resulted from a blow to the nose. The resulting sections shifted like tectonic plates, creating gaps of 1/16 to 1/8 of an inch, and are lifting slightly away from the plaster substrate. There are a few surface losses, most notably from the tip of the nose.

To treat the sculpture safely and appropriately, I addressed the following questions: What are the physical properties of the materials? What materials and methods are viable for treatment of the object? To what extent will the object be restored?
After carefully extracting tiny samples of wax from an area with surface loss I determined its melting range to be 147-151°F, which corresponds to that of beeswax, a material commonly employed by the artist.

Knowing the melting point of the wax, I could formulate a plan for stabilizing the portrait. There were several options: one was to stabilize the sections in their current configuration and fill the gaps with wax of a lower melting point. However, I preferred not to adhere the wax sections in their current configuration, but to somehow coax the sections back together into their original configuration, without marring the delicate wax surface. At a typical room temperature of 68° to 70°F (and at lower temperatures) the wax is too brittle to force into alignment and would break into smaller pieces. Warming the entire object slightly would increase the pliability of the wax but would also make the outer surface more vulnerable to damage. If, however, the object could be heated in such a way that just the interface of the wax and plaster would be directly heated-allowing the delicate wax surface to become only slightly warmed-then it might be possible to reposition the sections close to their original configuration without marring the pigmented wax surface.

But adhering the pieces is another challenge. Various solvents and adhesives have been suggested by colleagues, but based on experimentation, the only adhesive that seems viable is wax itself.

Since it would be too risky to experiment on the original object, I created mock-ups to try out various potential treatments. The mock-ups were intentionally damaged to simulate the kind of damage sustained by the original. Attempts to apply molten wax to the surface of the wax mock-ups have been unsuccessful and have proven this method to be unsatisfactory and extremely risky for treatment of the sculpture. I have been experimenting successfully with a more novel approach: using a microwave oven to melt wax at the interface of the wax and plaster. The microwaves do not heat the plaster or wax, but they heat water that has been fed into the interface. The beauty of this method is that it is very controllable. I can vary the amount of water, the location of the moisture and the duration of exposure to microwaves.

By controlling these variables I may be able to soften the wax from the interior without making the fragile surface more vulnerable to potential damage, allowing the fragmented sections to be pressed together. This procedure might also allow controlled melting of wax to adhere the sections to the plaster substrate.If this method were eventually employed for treatment of the sculpture, the metal rod would of course have to be extracted prior to irradiation.

Continued experimentation is necessary to assure the safety and maximal benefit of using microwaves to treat such an object. Shall we "nuke" Anna Pavlova's head? The answer right now is...maybe.

Matthew Fleischman is Carnegie Museum of Art's objects conservator.