Investigation and analysis of Ryukyu lacquerwares decorated with wisteria vine by pyrolysis GC/MS and 87 Sr/ 86 Sr isotope ratio

Three lacquer trays decorated with wisteria vine (rattan) produced in the 18–19th century in Ryukyu Kingdom were analyzed by cross‐section, pyrolysis gas chromatography/mass spectrometry, strontium isotope ratios ( 87 Sr/ 86 Sr), radioactive carbon‐14 dating, and field emission scanning electron microscope with energy dispersive X‐ray spectrometry. One sample had only one red lacquer layer, and the other two samples had two layers with top red lacquer and a bottom layer of natural lacquer, respectively. The 87 Sr/ 86 Sr isotope ratios of three samples were 0.7091–0.7107, consistent with that of the Japanese mainland (<0.7110). The wood species of lacquer objects were identified as Japanese white pine, Japanese cedar, and Cunninghamia lanceolata , which grow in the Japanese islands. The carbon‐14 dating results showed that the lacquer films were about 1719–1785. In pyrolysis gas chromatography/mass spectrometry, 3‐heptylphenol (C7) and 3‐pentadecylphenol (C15) were detected in the mass chromatograms at m / z = 108 and palmitic acid and stearic acid were detected in the mass chromatograms at m / z = 60, implying that the coating material was sap collected from Toxicodendron vernicifluum lacquer tree and included a drying oil. Energy dispersive X‐ray spectrometry revealed that mainly mercury sulfide was used as red pigment in these three Ryukyu lacquerwares.