Raman spectroscopic analysis of an English soft-paste porcelain plaque-mounted table

Raman spectroscopic studies were made of a porcelain fragment of a unique 18th century table with inlaid porcelain plaques prior to its restoration and compared with the body and glaze of a damaged, marked porcelain plate from the Rockingham factory. The spectra are consistent with the two specimens having the same manufacturing source around 1840. The analysis of the body of the plate and the plaque fragment shows that both contain beta-wollastonite, feldspar and calcium orthophosphate; in addition, a trace of gypsum was found on the bottom surface of the plaque fragment, indicating that plaster was used as an adhesive and bedding agent for the plaques on their wooden table-top substrate. The porcelain bodies of the plaque and the plate are classified as English soft-paste porcelain with bone-ash additive and differences in the spectra can be ascribed to changes in the firing temperature and kiln cycles. The glaze compositions are also very similar with the identification of borax in each specimen. It is concluded analytically that the porcelain plaques were derived from the Rockingham factory around 1835-40, which can be correlated with historical provenancing. Copyright (C) 2004 John Wiley Sons, Ltd.