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 © 2016 John Wiley & Sons, Ltd.