Investigation of Asian lacquer films using ToF-SIMS and complementary analytical techniques

Abstract

Lacquer has been used in Asian countries for thousands of years as a natural coating material owing to its durable, adhesive, decorative, and protective properties. Protection and restoration of lacquer-coated cultural remains has become an important subject, and identification of the lacquer types in old lacquer-wares has also become very important for conservation and restoration research. This paper provides identification of several molecular species of vegetal-source Asian lacquers with the aim of providing a methodology for application in the field of cultural heritage. Several chemical markers of the vegetal species in Asian lacquers were identified using a methodology consistent with the sampling restrictions required for cultural-heritage objects. Surface analytical methods such as time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize Korean, Chinese, and Vietnamese lacquers; avoiding time-consuming and destructive extraction processes. These ToF-SIMS results provided the structural characterization of a series of catechol derivatives. The ToF-SIMS spectra of Rhus vernicifera from Korea and China, and Rhus succedanea from Vietnam indicated a series of urushiol and laccol repeat units, respectively, in the mass range of m/z 0-1800. Because of its sensitivity, specificity, and speed of analysis, the ToF-SIMS technique can be used to investigate cultural lacquer-coated treasures as well as to discriminate among different Asian lacquer coatings or binding mediums for the conservation or restoration of lacquer-ware. Copyright (C) 2016 John Wiley & Sons, Ltd.