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OO8.4.1

RECENT CASE STUDIES IN THE RAMAN ANALYSIS OF ANCIENT CERAMICS : Glaze Opacification in Abbasid Pottery, Medici and 18th century French Porcelains, Iznik and Kûtayha Ottoman Fritwares and an Unexpected Lapis Lazuli Pigment in Lajvardina Wares

Ph. Colomban Laboratoire de Dynamique, Interactions et Réactivité (LADIR), UMR 7075, Centre National de la Recherche Scientifique & Université Pierre & Marie Curie, 2 rue Henry-Dunant, 94320 Thiais, France ABSTRACT

We demonstrate the potential of Raman spectroscopy as an on-site technique for the characterization of ancient ceramics. This non-destructive analysis offers a way to get information on the process and even sometimes on the date of ancient artifacts. Much information remains written in the microstructure of ceramics bodies and in the nanostructure of glasses, glaze and enamels. Raman signatures are specific to the technology that was applied to a given starting batch and to the process of manufacture. Recent studies that demonstrate : i) the use of cassiterite for opacification and its role in Islamic three-color wares and polychrome lustred pottery from the Abbasid to Fatimid period, ii) the invention of the “hybrid-paste porcelain” by the Duke of Medici, known as Medici porcelain and of the “softpaste” porcelain by the French Manufactures in the eighteen century (Chantilly, Mennecy, Saint-Cloud), iii) the development of the underglaze pigment technology by Iznik and then Kütayha Ottoman potters; iii) the use of lapis lazuli gem as an unexpected pigment in the Iran Lajvardina wares. Finally we explore the relationship between glass makers and potters.

INTRODUCTION

Leading experts generally base their certification of ancient artifacts on stylistic analysis and on a personal feeling involving the five senses. More objective proof is mandatory for authentication and dating purposes. We demonstrate the potential of Raman spectroscopy as a non-destructive on-site technique [1-7]. Salient features thus can be extracted from bodies, glazes and pigments from different types of production covering the history of ceramic industry. In this review we will demonstrate the potential of on-site Raman spectroscopy for the identification of precious artifacts and better understanding of past technologies. Tin oxide (cassiterite) is a very good Raman scatterer and its detection is straightforward from its 635-775 cm-1 doublet, for example see the Chantilly glaze in Figure 1. Thus, the recognition of its use is one of the very useful applications of Raman scattering. We review here some of our recent examinations. First, Abbasid copies of three-color Tang Dynasty pottery and eighth to fourteenth lustre pottery. We demonstrate the un-expected use of cassiterite to opacify some early Iznik fritwares as well the use of cassiterite to lighten some pigments [8]. The data processing of the Raman signature of Iznik and Kütahya pottery glaze is used to discriminate between early and late productions [9]. Particular attention is paid to Iznik and Kütayha pigment, the role of black