On-site identification of Sceaux porcelain and faience using a portable Raman instrument

Abstract

During the 18th century many European manufactures tried to imitate Chinese, Vietnamese and Japanese porcelain. To address the lack of kaolin source they had to test new processes inspired from the fritware technology. Unfortunately, the Sceaux Factory production is poor documented: it was only vaguely reported that different technologies were used to produce soft-paste and hard-paste porcelain as well as different kinds of faiences, including an undocumented “faïence japonnée”. In order to bring new information, a selection of 25 objects from the Département du Patrimoine et des Collections de la Cité de la Céramique, Sèvres, France, attributed to the 18th century Sceaux Factory production, has been analyzed with a portable 532nm Raman spectrometer in museum reserves. Identification of the crystalline phases of the body and glaze as well as pigments allows differentiating the different technologies. According to previous studies on porcelains produced by other factories in Paris area (Chantilly, Saint-Cloud, Mennecy, Vincennes/Sèvres, etc.), wollastonite (β CaSiO4) appears to be characteristic of soft-paste porcelain paste. Therefore, the absence of wollastonite peaks is consistent with a faience body and the concomitance with the presence of quartz peaks can correspond either to hard-paste porcelain or to faience. Cassiterite, wollastonite and quartz are identified as glaze opacifiers. Different olivine and pyrochlore compositions have been evidenced for blue and yellow pigments, respectively. This fact can be related to different pigment technologies (periods or Master).