Characterisation of decoration and glazing materials of late 19th-early 20th century French porcelain and fine earthenware enamels: a preliminary non-invasive study

This study focuses on the development of a non-invasive multi-analytical approach for the study of glazing and decoration materials used in French pottery from the late nineteenth and early twentieth century. The considerable commercial success of this art makes this time frame of particular interest as it led, among others, to a general modernisation of the production processes and materials to satisfy the increased demand and the flourishing trade of potteries: new ceramic bodies, alternative glaze formulation and a wider range of materials became available. Considering the pristine conservation state of the twenty-one selected samples (deriving from six factories or manufacturers in four different production areas in France), a multi-technique, non-invasive and non-deliberatively destructive analytical approach was chosen for the characterisation of glazes, pigments and other superficial materials. Each object was firstly observed with optical microscopy and subsequently underwent elemental composition analyses such as MA-XRF (macro X-ray fluorescence) and IBA (ion beam analyses) at the INFN LABEC Laboratory in Florence. For the identification of some of the compounds present in coloured enamels, a selection of the objects was analysed with Raman spectroscopy at the ICCOM CNR in Pisa.