Non-Invasive Raman Analysis of 18th Century Chinese Export/Armorial Overglazed Porcelain: Identification of the Different Enameling Techniques

Anh-Tu Ngo,Nicolas Fournery,Philippe Colomban

doi:10.3390/heritage5010013

Abstract

Six rare porcelains of the Qing Dynasty, in particular, dishes ordered respectively for Philibert Orry, the Duke of Penthièvre and a tureen from the service of Louis XV, with royal coat-of-arms, were analyzed non-invasively by Raman microspectrometry. A coffee pot with a rare decoration attributed to Cornelius Pronk was also analyzed as well as two plates, one decorated with an Imari-style pattern and the second post-decorated in the Low-Countries/Holland. The enamel types and coloring or opacifying agents were identified on the basis of combined Raman and SEM-EDXS analysis previously published as well as new section and surface analysis of five plate samples representative of different technologies (blue-and-white, Famille rose). The use of lead oxide for the preparation of overglaze is demonstrated. For the first time, the use of borax in the blue overglaze according to the recipe from the 1753 manuscripts of French chemist Jean Hellot is demonstrated on Chinese porcelain. This fact, like the use of cobalt free of manganese, demonstrates the use of European ingredients and/or recipes for ceramics exported from China to Europe. The highlighting of the use of different recipes or raw materials for porcelain from the same period can therefore be the signature of different workshops. For instance, three different Raman signatures of red decoration were identified from the hematite vibration modes: very narrow modes for Pronk’ coffee pot and Louis XV tureen, broad for Orry’ dish and intermediate for the others. Three workshops are thus expected. It is interesting to note that the use of arsenic for the realization of white enamels corresponds to the latest objects, made after 1738. China was therefore in the 18th century both an importer of European know-how, design and an exporter of enameled products made with imported technologies to Europe.

Highlights

The import of Chinese blue-and-white porcelain by the Portuguese traders in the16th century and on a larger scale in the 17th and 18th century by the Dutch, English, French and Swedish companies led to a craze among European elites for Chinese and Japanese ceramics [1–9], which decorations inspired in return those of the many porcelain and faience factories built in Europe in the 18th century [10–12]
One of the fundamental contributions of European enameling technologies to Japanese and Chinese craftsmen is the superposition of layers of colored enamels to obtain a complex, naturalistic decoration allowing to obtain on different supports a similar decoration to that obtained in oil painting
In the lack of joint XRF measurement, a good-knowledge of the Raman signatures obtained on similar samples analyzed by SEM-EDXS appears to be sufficient for an unequivocal identification of most of the phases constituting the glaze and the enamels

Summary

Introduction

The import of Chinese blue-and-white porcelain by the Portuguese traders in the16th century and on a larger scale in the 17th and 18th century by the Dutch, English, French and Swedish companies led to a craze among European elites for Chinese and Japanese ceramics [1–9], which decorations inspired in return those of the many porcelain and faience factories built in Europe in the 18th century [10–12]. One of the fundamental contributions of European enameling technologies to Japanese and Chinese craftsmen is the superposition of layers of colored enamels (so-called overglaze) to obtain a complex, naturalistic decoration allowing to obtain on different supports (glass, metal or ceramic) a similar decoration to that obtained in oil painting. This technique initially developed by enamellers on metals requires strongly colored enamels (highly loaded with one or more coloring agent(s)) fired at decreasing temperatures

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