Identification of pigments from the Shrine of Kaiping Diaolou by micro-Raman spectroscopy

Abstract

Shrines (or altars) are constructed in China for worshiping ancestors, Bodhisattva, and God of Wealth. In this work, pigments from the shrine of Kaiping Diaolou tower were analyzed by micro-Raman spectroscopy, in conjunction with other analytical methods including scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF). Paintings of the shrine were composed of 2-3 pigment layers and the total thickness was determined as about 200-300 μm by optical microscopy and SEM, indicating the fine painting skills applied in the construction of the shrine. The green pigments on the surface layer of the green fragment were identified as a mixture of lead phthalocyanine (PbPc) and cornwallite (Cu 5(AsO4)2(OH)4) by XRF and micro-Raman spectroscopy with two different excitation wavelengths (488 and 785 nm). Underneath the green layer, red and yellow ochre were found. The pigments on the surface layer of red and blue fragments were identified as hematite (Fe2O3) and lazurite or synthetic ultramarine [(Na 8(Al6Si6O24)S3)], respectively. Finally, the pigments under the two surface layers were identified by EDX and micro-Raman spectroscopy as chromium oxide (Cr2O 3), gypsum (CaSO4·2H2O) and calcite (CaCO3). Copyright © 2011 John Wiley & Sons, Ltd.