Gold leaf decoration on medieval islamic glazed ceramics - in search of technological features with XRD
Résumé
Considered as luxury earthenware, haft-rangi ceramics are sometimes enlightened with gold leaves. This type of decoration appears on vessels in the Iranian world in the 12th-13th centuries and is exported to Central Asia on architectural tiles in the 14th-15th centuries. The questioning raised by this type of decoration mainly concerns the production process, its genesis and evolution in its well defined geo-chronological context. The innovative approach of the physico-chemical analysis of such a decoration so peculiar to medieval Islamic ceramic is thus essential. The study is concerned with the micro-structural features of the gold leaf itself. Because the studied samples are part of the cultural heritage, the non-destructiveness of the experiments is of very high interest. Therefore, some diffraction patterns, characteristic of the polycrystalline gold surface of the archaeological artefacts, have been obtained by synchrotron radiation at the ESRF. The results show that the diffractograms bear the signature of both mechanical and thermal treatments which the gold leaves underwent.