Non-Invasive Mobile Raman and pXRF Analysis of Armorial Porcelain with the Coat of Arms of Louis XV and Others Enamelled in Canton: Analytical Criteria for Authentication

Abstract

Nine glazed porcelain artifacts bearing the coat of arms of France, from King Louis XV tableware orders, were analysed at the laboratory or in their conservation secure room. Based on the experience acquired in the study of 18th century European and Chinese porcelain using mobile XRF (pXRF) and Raman microspectroscopy, a comparison of the impurities in the paste (Y, Rb, and Sr), the elements associated with cobalt in the blue overglaze (Bi, Mn, Zn, and As) and those present in the tin yellow and Naples yellow pigments (Sn, Sb, and Zn) highlights the use of different raw materials for some of these objects. Differences regarding the Ag content in the gold decorations also provide information. Raman identification of the different types of yellow pigment confirms the categorization. The results obtained on the Louis XV tableware are compared to those of "Chine de commande", attributed to the same places and periods of production or recognized copies. The clustering of the quantitative comparison pXRF signals of the abovementioned elements and a consideration of the Raman parameters of the yellow pigments appear to be effective tools for object categorization to confirm or refute questions about the authenticity of objects.