Non-invasive Raman analyses of Chinese huafalang and related porcelain wares. Searching for evidence for innovative pigment technologies

Eighteen Chinese painted enamelled porcelains and three Chinese enamelled Yixing stonewares dated to the 16th to 19th centuries and kept at the Musee national des arts asiatiques-Guimet (MNAAG), have been analysed with a mobile Raman set-up to identify their enamelling technology. Different Grand Feu (leadless or lead-poor colourless and blue enamel) and Petit Feu (lead-rich red (hematite), yellow and green (Pb-Sn/Sb/X pyrochlore) and black enamels) glazes were respectively identified on wares from the wucai group, the Famille verte group, and the huafalang group. Calcium phosphate was detected in a 17th century vase as a rare opacifier. Cassiterite was identified in the light green glaze of an imperial huafalang bowl dated to the final period of the Kangxi reign (1662-1722), ca. the 1st quarter of the 18th century. Lead arsenate was identified in the blue glaze of two artefacts, a huafalang bowl and a painted enamel water dropper, and in the blue enamel of a 19th century Yixing teapot. Lead arsenate found in some of the blue enamels appears to arise from the arsenic content in Erzgebirge cobalt ores (Saxony) and not due to voluntary addition. This may prove the use of raw materials or enamel powder imported from Europe in developing these opaque colours. The use of lead arsenate as white opacifier is clear for a water dropper bearing the Yongzheng emperor's mark (r. 1723-1735). The technological palette appears different for the artefacts expected to originate from the same period and provenance (imperial workshop) which is consistent with a period of intense innovation, open to technological skill from abroad i.e. from French/European painted enamel technology as revealed by ancient French (Jesuits) and Chinese historical reports.