Identification of laccol as a paint binder in Neolithic pottery from China

Some precious painted pottery have been excavated from a late Neolithic site (6000-5300 BP) in China recently. The materials and technique of the paint were comprehensively studied. The analytical techniques conducted include optical microscope (OM), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Ultra Performance Liquid Chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) and thermally assisted hydrolysis-methylation pyrolysis-gas chromatography/mass spectrometry (THM-Py-GC/MS). The results revealed the painted pottery is lacquer-painted pottery, which is the earliest evidence of using laccol as binding media to paint pottery. Moreover, a two-layer structure of the paint technique was found. Cinnabar and a kind of yellow dye were detected in the first layer, while iron red was determined in the ground layer. Laccol, instead of urushiol as a binding medium, was identified in both two layers. Laccol is the maker compound from the tree of Toxicodendron (Rhus) succedanea, which mainly grows in Vietnam. Its presence in the painted pottery represents that the use of Toxicodendron (Rhus) succedanea resource can be as early as the late Neolithic period in China. The possibility of the origin of laccol was also discussed in the paper.