Discrimination of traditional plant fibers used in Japanese cultural artifacts by infrared spectroscopy

Abstract

The fibers of kudzu (Pueraria montana var. lobata), basho (Musa basjoo), hemp (Cannabis sativa), and ramie (Boehmeria nivea var. nipononivea) plants were once widely used to produce fabrics. Indeed, the production of dyed fabrics using these fibers, which were commonly used in historical cultural artifacts, was widespread until cotton became popular. It is highly likely that fabrics composed of these four fibers have been misidentified in the process of preserving and/or restoring cultural artifacts. However, reliable methods for discriminating these four types of fiber have not yet been established. In this study, infrared spectroscopy and multivariate analysis [principal component analysis (PCA), Fisher’s discriminant orthogonal decomposition (FDOD), and partial least-squares discriminant analysis (PLS-DA)] were used to discriminate among threads and fabrics composed of these four fibers. First, FDOD or PCA was used to separate the samples to two groups; one group contained kudzu and basho, and the other contained hemp and ramie. PLS-DA was effective for discriminating between kudzu and basho, and between hemp and ramie. External validation revealed that this discriminant procedure could be applied to the practical identification of historic dyed fabrics composed of these materials.