Reflectance imaging spectroscopy for the study of archaeological pre-Columbian textiles

• Published in: Microchemical journal 2024-05, Vol.200, p.110168, Article 110168
• Main Authors: Grillini, Federico, de Ferri, Lavinia, Pantos, George Alexis, George, Sony, Veseth, Margunn
• Format: Article
• Language: English
• Subjects: Dyes mapping; Fibers mapping; Hyperspectral imaging; Reflectance imaging spectroscopy; Textiles
• ISSN: 0026-265X
• DOI: 10.1016/j.microc.2024.110168

[Display omitted] •Pre-Columbian textiles were studied using hyperspectral imaging (400–2500 nm).•Spectral unmixing was used to identify endmembers of possible dye mixes.•Both an a priori and an automatic processing approach were used to define endmembers.•The selected endmembers were mapped to reveal patterns of dyes and fiber materials.•A comparison between maps obtained with the two selection approaches is provided. In this study, two pre-Columbian textiles belonging to the Middle Orizon and Necropolis Paracas Cultures are studied by means of reflectance imaging spectroscopy. The non-invasive analysis of artifacts is a fundamental step when investigating the constituent materials and their state of conservation in order to target subsequent sampling campaigns in specific areas. The paper aims to explore the spectral properties in the Visible Near-Infrared (VNIR) and Short-Wave Infrared (SWIR) intervals and investigate the spectral correlation between the relevant identified regions of interest. Two ways of selecting relevant spectral signatures are proposed: manual selection and automatic filtering. According to these two selections, the regions of interest undergo spectral unmixing in the VNIR interval to investigate which dyes had been used as such. The hyperspectral images are then mapped according to the selected endmembers in both VNIR and SWIR intervals. Small areas that feature the usage of a peculiar black thread have been given particular attention and imaged with a macro objective. The SWIR mapping on one of the samples has helped to reveal a pattern that can be ascribed to the manufacturing processes or the burial conditions.