A stone kneeling figure in the Art Institute of Chicago: new evidence from scientific investigations and archaeological finds in China

Abstract

An ancient stone sculpture of a figure kneeling with hands bound behind him was bequeathed to the Art Institute of Chicago in 1950 and for many years had no known counterpart. Comparable finds are now confirmed by a group of similar figures discovered since 1984 at several archaeological sites in the Chengdu plain of China's southwestern Sichuan province, which are datable to the late second millennium B.C. E. Unlike those recently unearthed figures, carved of more roughly textured, yellowish gray or dark green stones, some of which preserve traces of pigment that partially highlight their facial features, the Art lnstitute's example bears a smooth and shiny blackish green surface. Questions about the nature of this surface--whether coated with a paintlike film and/or darkened by heating- prompted a thorough investigation of the figure. Nondestructive techniques such as in situ Raman microscopy, x-ray diffraction, environmental scanning electron microscopy, and near infrared reflectance spectroscopy were used to fully characterize the sculpture. Fourier transform infrared spectroscopy was employed to shed light on the nature of applied materials such as fills, surface accretions, and possible coatings. Results of these extensive scientific examinations, evaluated together with experimental tests of heating and polishing as well as with relevant archaeological evidence recently brought to light, have enhanced our understanding of the surface treatment of this fascinating and hitherto enigmatic sculpture.

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