AMS radiocarbon dating of a Western Han period (3^rd-1^st century BC) lacquer-coated earthenware jar

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. C 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 C-accelerator mass spectrometry suggests that other lacquer-coated objects might be dated using a similar approach.

Radiocarbon Dating of Asian Lacquers: Molecular Characterization and Assessment of a Pretreatment Method Prior to Accelerator Mass Spectrometry

“…From the authors' knowledge, there are only few studies published in English dealing with the radiocarbon ( 14 C) dating of Asian lacquer objects (Sato et al 1969;Strahan 1993;Hodgins et al 2002;Beavan et al 2012;Sokha 2014;Orillaneda 2016;Sung et al 2016;Matsumoto 2018;Wu et al 2018;Grave et al 2019;Park and Lee 2019;Brunskog and Miyakoshi 2021b;Durier et al 2021). Of these studies, only some involved the direct dating of the lacquer, but pretreatment methods used were not always described.…”

“…For others, the researchers performed 14 C dating on other compounds taken from the lacquered objects, such as wood or textiles. When a pretreatment methodology on the lacquers was reported, it was usually an acid washing or an acid-alkali-acid (AAA) pretreatment, also called acid-base-acid (ABA) (Hodgins et al 2002;Grave et al 2019;Durier et al 2021). Hence, due to incomplete information, there is a need to further explore 14 C dating of Asian lacquer-based materials.…”