Opaque ancient K2O–PbO–SiO2 glass of the Southern Song Dynasty with fluorite dendrites and its fabrication

Abstract

Here we first report a piece of K 2 O-PbO-SiO 2 ancient glass opacified by fluorite dendrites with archaeological background. This piece of glass was excavated from Nanhai I shipwreck, a merchant ship once heading for Southeast Asia, but sinking near Yangjiang, Guangdong province. Analysis of scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and Raman spectroscopy were used to identify the glass matrix and the fluorite dendritic crystals within it. The elemental feature is consistent with the prevailing K 2 O-PbO-SiO 2 glass system during Tang and Song Dynasties. However, the presence of fluorite dendrites with almost no Na, Al and P elements strongly suggests an astonishing conclusion that the fluorite has already been used as an opacifying agent around 800 years ago. Moreover, through replication of glass samples with similar compositions to the ancient one, it is suggested that fluorite dendrites with a similar size can be obtained when fired at around 1000-1050 °C and cooled within the furnace. On the basis of different crystal growth outcomes of two cooling strategies and the presence of the large undisturbed dendrite, it is inferred that the original glass vessel was probably made though die-casting instead of blowing technique.

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

“…In the yellow area, the presence of intense Pb and Sn peaks indicates the use of lead pyrochlore pigment (also called Naples yellow ) [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. The red area also shows the significant contribution of copper, indicating the ancient technique of red coloration in Chinese glass and glazes [ 75 , 76 , 77 , 78 , 79 , 80 , 81 ] where the red color is obtained by dispersion of Cu° nanoparticles. Additionally, the Fe peak seems to be greater than in the white and blue enamels, pointing out that it may have contributed to the red color in the form of hematite precipitation.…”

“…Raman analysis is particularly effective in the identification of crystal phases present in the glassy silicate matrix. In the white cloisonné enamel of the incense burner, the weak peak at 315 cm −1 is assigned to fluorite (CaF 2 ) as an opacifier which specifically belongs to an ancient Chinese tradition of glass opacification [ 38 , 52 , 81 , 88 ]. The continuous use of fluorite in Chinese glassy materials has been reported from the Tang Dynasty to the Qing Dynasty, in glass objects [ 81 ] as well as cloisonné enamels [ 38 , 87 , 88 , 89 ].…”

pXRF Data Evaluation Methodology for On-Site Analysis of Precious Artifacts: Cobalt Used in the Blue Decoration of Qing Dynasty Overglazed Porcelain Enameled at Customs District (Guangzhou), Jingdezhen and Zaobanchu (Beijing) Workshops

“…The opacification in white was traditionally obtained in China by the use of fluorite (CaF 2 ) [10,14,25,35]. The use of lead arsenates with variable and complex compositions [11][12][13]21,23,[25][26][27][28][29][30][31] is also considered a Western contribution.…”

“…The European technique for obtaining different shades of green by dispersing a yellow pigment ('pure' tin yellow or, more widely, the different Naples yellows with a complex pyrochlore structure and composition) in a blue-colored matrix by cobalt ions is much more versatile [11,[30][31][32][33][34][36][37][38][39][40][41][42][43]. Shades of pink to purple are obtained by the dispersion of colloidal gold prepared by dissolving gold in aqua regia and the precipitation of gold in the form of nanoparticles by a redox reaction with the addition of tin (purple of Cassius) or arsenic (Perrot's red), the color depending on the size of the nanoparticles then dispersed in the glassy silicate [11,21,34,35,44,45].…”

A Transparent Dialogue Between Iconography and Chemical Characterisation: A Set of Foreign Stained Glasses in Portugal

“…In the present work, a relation between the stylistic, formal and iconographic studies, and the chemical characterisation of some of the glass fragments allowed to attribute the set to the same origins, highlighting the widely recognised and used potential of heritage scientific studies for solving historical complex questions (e.g. [8,9]). Micro Energy Dispersive X-Ray Fluorescence (µ-EDXRF) was used in order to obtain a non-destructive characterisation of the composition the glass and grisaille used in the production of three of the panels (Virgin of the Apocalypse, Saint Ambrose, Saint Gregory).…”