The Technology Transfer from Europe to China in the 17th–18th Centuries: Non-Invasive On-Site XRF and Raman Analyses of Chinese Qing Dynasty Enameled Masterpieces Made Using European Ingredients/Recipes

Abstract

Two masterpieces of the Qing Dynasty (1644–1912 CE), one in gilded brass (incense burner) decorated with cloisonné enamels stylistically attributed to the end of the Kangxi Emperor’s reign, the other in gold (ewer offered by Napoleon III to the Empress as a birthday present), decorated with both cloisonné and painted enamels bearing the mark of the Qianlong Emperor, were non-invasively studied by optical microscopy, Raman microspectroscopy and X-ray microfluorescence spectroscopy (point measurements and mapping) implemented on-site with mobile instruments. The elemental compositions of the metal substrates and enamels are compared. XRF point measurements and mappings support the identification of the coloring phases and elements obtained by Raman microspectroscopy. Attention was paid to the white (opacifier), blue, yellow, green, and red areas. The demonstration of arsenic-based phases (e.g., lead arsenate apatite) in the blue areas of the ewer, free of manganese, proves the use of cobalt imported from Europe. The high level of potassium confirms the use of smalt as the cobalt source. On the other hand, the significant manganese level indicates the use of Asian cobalt ores for the enamels of the incense burner. The very limited use of the lead pyrochlore pigment (European Naples yellow recipes) in the yellow and soft green cloisonné enamels of the Kangxi incense burner, as well as the use of traditional Chinese recipes for other colors (white, turquoise, dark green, red), reinforces the pioneering character of this object in technical terms at the 17th–18th century turn. The low level of lead in the cloisonné enamels of the incense burner may also be related to the use of European recipes. On the contrary, the Qianlong ewer displays all the enameling techniques imported from Europe to obtain a painted decoration of exceptional quality with the use of complex lead pyrochlore pigments, with or without addition of zinc, as well as cassiterite opacifier.

Full Spectral Range Raman Signatures Related to Changes in Enameling Technologies from the 18th to the 20th Century: Guidelines, Effectiveness and Limitations of the Raman Analysis

“…Figures 1-3 present the characteristic ceramics and enameled metalworks used as a reference of representative spectral signatures. The selection was made on the basis of hundreds of objects and shards analyzed in the laboratory and in situ measurements for the last twenty years [1][2][3][4][5][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Artefacts have been selected with the following criteria: variety of colors, structural types of pigments, substrates, firing temperature, etc.…”

“…The full spectral range is considered here. Vincennes (France) Palette cup porcelain [21] Sèvres (France) Coffee cup porcelain [21] Comte d'Artois factory(France) Vase porcelain [22] China Dish porcelain [23] X China Dish porcelain [23] X China Tea pot porcelain [24] China Bottle porcelain [24] Swiss Watch gold [15] France Watch gold [15] X China Ewer gold [25,26] France Sèvres (France) Ewer metal [27] Sèvres (France) Palette porcelain [2] Nevers (France) Factory (OA7739, Louvre) [22]; (d) Famille rose plate, Chinese factory (Private Coll. ), circa 1770 [23];…”

“…), circa 1770 [23]; (e) 'Chine de commande' porcelain plate, circa 1740-1750 (R1025, Louvre) [23]; (f) 'Thousand flowers pattern' tea pot porcelain, Jingdezhen Imperial Factory, 2nd half of 18th century (F1429C, Fontainebleau) [24]; (g) Chinese porcelain bottle (TH457, Louvre), Qianlong reign [24]; (h) enameled watch, end of 17th century-beginning of 18th century, Swiss factory (OA10079, Louvre), adapted with permission from ref. [15], 2020, Elsevier Masson SAS; (i) ewer, with painted (detail) and cloisonné enamel on gold body, 2nd half of 18th century (F1467.1, Fontainebleau), Qianlong Imperial workshop [25,26]. The collections and the inventory number of the objects are indicated.…”

“…The preparation of enamels has greatly evolved since the 15th century (Renaissance) with the development of European artisanal productions including the empirical knowledge of chemical processes and their circulation by means of the recipe books and later with the huge advances in industries and chemical technologies during the 19th century [17]. Globalization of the enameling technology starts during the 17th century with the longdistance trips and trade of European experts [12,[21][22][23][24][25][26].…”

“…On the other hand, the book by Richard A. Eppler and Douglas R. Eppler published in 2000 [39] presents a complete survey of contemporary enameling technologies. Based on these works and our previous publications [2,4,5,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][41][42][43], Table 2 lists the main structural types of pigments from different historical periods. The different phases are classified according to the criteria used in solid state chemistry and ceramics textbooks [48] for structural types.…”