Natural lacquer was used as a coating and an adhesive 8000 years ago, by early humans at Kuahuqiao, determined by ELISA

Natural lacquer is one of the first polymeric materials used by humans and has both functional and aesthetic uses. It has been used as coating by human since the Neolithic Age. It was discovered that lacquer was not only used as a coating but also an adhesive at the Kuahuqiao site 8000 calibrated years before present. This site, a Neolithic settlement, is located in the Chinese Yangtze River Delta. The three lacquered relics-obtained there consisted of a mulberry bow, the earliest known canoe-like boat, and a broken pottery fragment. The mulberry bow coated with lacquer film has been reported. There is a hole at the bottom of the canoe-like boat and it was repaired by a timber and an adhesive, recently. And the pottery fragment was also repaired by an adhesive, 8000 years ago. The analysis of infrared showed that the coating of the bow and the adhesives of the boat and the pottery are likely to be natural lacquer. However, the coating of the bow and the adhesive of the boat are impure, because of burial conditions and post-processing. They don't meet the requirements of Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), the common method to identify lacquer. Therefore, enzyme-linked immune sorbent assay (ELISA) was selected as the main analytical method. Detection of lacquer by ELISA is almost no requirements for samples, therefore it can be used to search for earlier lacquerwares and identify the lacquerwares in poor condition. It was determined that the coating of the bow and the adhesives of the boat and the pottery were all the natural lacquer from Toxicodendron vernicifluum by ELISA. Only the adhesive of the pottery was analyzed by Py-GC/MS, and it determined that it was natural lacquer, consistent with the result of ELISA. These discoveries prove that natural lacquer was widely used as a coating and an adhesive by Neolithic humans at the Kuahuqiao site, 8000 years ago.