AMS radiocarbon dating of a Western Han period (3 rd -1 st century BC) lacquer-coated earthenware jar
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AMS radiocarbon dating of a Western Han period (3rd-1st century BC) lacquer-coated earthenware jar G. W. L Hodgins1, 2, E. Farrell3, and R. D. Mowry4 1 University of Oxford, Oxford Radiocarbon Accelerator Unit, Oxford, U. K., 2University of Georgia, Center for Applied Isotope Studies, Athens GA, U.S.A., 3Harvard University Art Museums, Straus Center for Conservation, Cambridge MA, U.S.A., 4Harvard University, Arthur M. Sackler Museum, Cambridge MA. U.S.A. ABSTRACT The chronometric dating of ceramic objects is normally achieved by thermoluminscence techniques (TL). Here we report both TL and a radiocarbon measurements on a Chinese earthenware hu jar (Harvard University Art Museums LTL1.2001.23 a,b). TL dates were obtained from earthenware core samples using established methods. The radiocarbon date was obtained from an organic coating present on the jar surface. The coating was preliminarily identified as urushi by a comparison of its FTIR absorption spectrum to absorption spectra obtained from modern and ancient lacquer standards. The material was found to be insoluble in a variety of solvents, mineral acids, and bases. Combustion and elemental analysis revealed that 64% of the coating mass was carbon. 14C measurement by AMS was carried out on a 3.9 mg sample of chemically cleaned lacquer. This measurement generated a date of 2191 ± 38 BP. Calibration of this measurement placed the age of the jar between 390BC and 160 BC at the 95% confidence interval. The calibrated radiocarbon date corroborated the TL measurement placing the jar at between 2400 and 1500 years old (400 BC to 500 AD). These findings also agreed with stylistic evidence that the jar was produced during the Western Han period (206 BC-AD 9). The literature on urushi composition, its pigment compatibility, its high carbon content, its apparent chemical stability, and the small sample required for 14C-accelerator mass spectrometry suggests that other lacquer-coated objects might be dated using a similar approach. INTRODUCTION One aspect of research in the field of accelerator mass spectrometry investigates the dating of new materials. This report is a preliminary investigation into radiocarbon dating urushi, the natural oriental lacquer. Urushi is a remarkably durable material. Lacquerware objects have survived from the beginning of the Chinese Neolithic (ca. 6000 years ago) [3]. Traditional methods of construction involve the application of lacquer over a substrate composed of wood, textile, or basketry. Many such examples survive from as far back as the late Zhou and Han periods (5th to 1st Century B.C) [5]. A much more rarely encountered composition is lacquer-coated earthenware. A lacquercoated earthenware hu jar (figure 1) was recently presented to the Harvard University Art Museums. The vessel, one of a pair, is stylistically related to lacquered earthenware vessels excavated from Western Han tombs in Shandong and Hubei Provinces [5]. A striking feature of the jar is the remarkable state of preservation of its lacquer coating. Although the age of th
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