Determination of the type of lacquer on East Asian lacquer ware

Abstract

Simple and easy analytical methods, which are applicable to precious artistic objects, have long been desired to determine the type of lacquer on lacquer ware. Direct inlet mass spectrometry (DIMS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were applied to the determination of the coating film on a lacquered wooden dish obtained in Okinawa. The above two-step mass spectrometry confirmed the coating film: the lacquer to be East Asian lacquer, or natural urushi derived from Rhus verniciflua. These two-step analyses are very useful for the determination of the type of lacquer on any lacquer ware. The first step analysis with DIMS is used to distinguish the natural urushi including the urushi-type lacquers from non-natural urushi: imitation urushi and lacquer containing synthetic resins. And the second step with Py-GC/MS is used to discriminate one type among the three natural urushi-type lacquers. These two-step analyses need only a small amount of sample ranging 0.01–0.5 mg without any pre-treatment so that these analyses can be used for precious lacquer ware with archeological interest.