In situ noninvasive Raman microspectroscopic investigation of polychrome plasterworks in the Alhambra

A groundbreaking non-invasive Raman microspectroscopic analysis of the Alhambra's polychrome plasterworks, particularly in the Hall of the Kings, revealed the presence of ancient pigments like cinnabar and minium, alongside their degradation products. Notably, the study identified natural lapis lazuli in most blue decorations, confirming its origin, while synthetic ultramarine blue was detected in a recently restored vault. Conducted during conservation work using a portable Raman microspectrometer positioned on scaffolding, this method provided real-time data to conservators despite challenges like micro-probe positioning and scaffold vibrations. The findings highlight the potential of Raman spectroscopy for in situ analysis of cultural heritage sites.

Dominguez-Vidal, A., Jose de la Torre-Lopez, M., Rubio-Domene, R., & Ayora-Cañada, M. J. (2012). In situ noninvasive Raman microspectroscopic investigation of polychrome plasterworks in the Alhambra. The Analyst, 137(24), 5763. https://doi.org/10.1039/c2an36027f