2 EXPERIMENTAL

FIRST, several photographs were taken of the glassy fracture in the plastic, using our Zeiss Epitechnoscope (Fig. 2). Small samples of the plastic were removed under the stereomicroscope and solubility tests were made. The plastic was not soluble in naphtha, slightly soluble in toluene, readily soluble in MI2 solvent mixture (toluene 70%, ethanol 10%, ethylene dichloride 10%, cellosolve 5%, cellosolve acetate 5%), and soluble in ethylene dichloride.

Fig. 2. Detail of conchoidal fracture. Magnification ca. �4 (to 2�″ by 3�″ print).

A small sample was removed from behind the proper left eye for identification by infrared spectrometry. The sample was sent to the Conservation Analytical Laboratory of the Smithsonian Institution (CAL no. 1538) and was found to be a styrenated alkyd resin (Fig. 3a). After some thought about what resins might have been employed, considering the fact that it was not a methyl methacrylate, an epoxy or a polyester, the commercially available plastic “Clearcast” (purchased at American Handicrafts, Washington, D.C.) was tested after setting by the Conservation Analytical Laboratory (CAL no. 1615, Fig 3b). The two samples proved to be essentially identical. These analyses gave us an idea, at least, of what the original material might be.

Fig. 3. Two infrared spectrometer traces. The lower shows a sample of Clearcast plastic; the upper shows a trace from the clear plastic of the mask.