XRF CHARACTERIZATION OF A QINGBAI EWER: GLAZE AND BODY COMPOSITION IN THE CONTEXT OF SONG DYNASTY CERAMIC TECHNOLOGY

Keywords: Qingbai porcelain, Song Dynasty, Jingdezhen, Hutian kiln, XRF analysis, ceramic technology, calcium glaze, Chinese ceramics, archaeometry, provenance studies Abstract This study presents the results of portable X-ray fluorescence (pXRF) analysis of a Qingbai-type ceramic ewer attributed to the Song Dynasty ceramic tradition of China. Two analytical measurements were performed: one on the glazed exterior surface and one on an unglazed area of the base representing the ceramic body. The results demonstrate a clear chemical distinction between glaze and body. The glaze is characterized by elevated calcium content (9.093 wt.% Ca) combined with silica-rich composition and low concentrations of lead. The ceramic body exhibits significantly lower calcium content (1.013 wt.% Ca) together with increased aluminum, iron, and titanium concentrations. The compositional relationship between glaze and body is consistent with the technological structure of traditional high-fired Qingbai wares, in which a calcium-rich glaze was applied to an aluminosilicate ceramic body. Trace element distribution, including Rb, Sr, Zr, Nb, Y, La, Ce, and Ba, provides additional geochemical information relevant to provenance studies. Morphological characteristics and compositional data together place the object within the Qingbai technological tradition associated with Song-period Chinese ceramic production. 1. Introduction Qingbai (青白瓷) represents one of the most significant ceramic traditions of Song China (960-1279 CE). Characterized by a translucent bluish-white glaze and refined porcelain body, Qingbai ceramics achieved wide distribution throughout East Asia and beyond. The most famous production center was Jingdezhen, particularly the Hutian kiln complex, although comparable wares were manufactured in several regions of southern China. Recent archaeometric investigations have demonstrated that compositional analysis of both glaze and ceramic body provides valuable information concerning manufacturing technology, raw material selection, and kiln traditions. X-ray fluorescence spectroscopy has become an important non-destructive method for evaluating historical ceramics and comparing archaeological materials with museum and private collection objects. The present study examines a Qingbai-type ewer using portable XRF analysis in order to characterize the chemistry of both glaze and body and to place the object within the broader technological framework of Song-period ceramic production. 2. Description of the Object The investigated vessel is a ceramic ewer with: globular body; high cylindrical neck; everted rim; elongated curved spout; loop handle; molded floral decoration in relief. The relief ornament appears to represent peony motifs arranged around the vessel body. The glaze exhibits a pale grey-green to bluish-green coloration typical of Qingbai wares. Increased color intensity is observable within recessed decorative areas, indicating local variations in glaze thickness. The base contains a clearly defined unglazed area exposing the ceramic body. The exposed body is light beige to pinkish-beige with scattered dark inclusions and a sharp transition between glazed and unglazed zones. These morphological characteristics correspond closely to established Qingbai vessel forms of the Song period. 3. Materials and Methods Portable X-ray fluorescence analysis was conducted on 3 November 2026 using a Geochem (3-Beam) Extra spectrometer. Measurement conditions: acquisition time: 30 seconds; analytical mode: Geochem (3-Beam) Extra; non-destructive in situ analysis. Two measurements were collected: Measurement 14 Glazed outer surface of the vessel. Measurement 15 Unglazed base representing the ceramic body. Results are reported as elemental concentrations in weight percent and parts per million (ppm). Major elements were additionally converted into oxide-equivalent values to facilitate comparison with published archaeometric studies of Qingbai ceramics. 4. Results 4.1 Elemental Composition Table 1. Principal elemental concentrations Element Glaze (%) Body (%) Si 36.80 29.49 Al 7.89 14.25 Ca 9.093 1.013 K 2.072 2.768 Fe 0.529 1.073 Ti 570 ppm 1300 ppm Mn 1057 ppm 677 ppm Y 100 ppm 125 ppm Pb 26 ppm 103 ppm The glaze contains approximately nine times more calcium than the body. In contrast, the body contains: substantially higher aluminum; higher iron; higher titanium concentrations. This compositional separation demonstrates the use of chemically distinct materials for glaze and ceramic body. 4.2 Trace Elements Table 2. Selected trace elements (ppm) Element Glaze Body Rb 167 281 Sr 126 29 Y 100 125 Zr 47 63 Nb 19 23 Ba 199 230 La 160 ND Ce 140 ND Pb 26 103 The trace-element spectrum reveals a geochemical signature typical of high-fired aluminosilicate ceramic systems and provides a basis for future provenance comparisons with kiln production centers in Jiangxi Province and related Qingbai manufacturing regions. 5. Oxide Equivalent Composition Table 3. Oxide-equivalent values Oxide Glaze Body SiO₂ 78.72% 63.10% Al₂O₃ 14.91% 26.92% CaO 12.72% 1.42% K₂O 2.50% 3.33% Fe₂O₃ 0.76% 1.53% TiO₂ 0.095% 0.217% The glaze is dominated by silica and calcium, whereas the body exhibits a more refractory aluminosilicate composition. 6. Glaze Technology The most significant feature of the glaze is its elevated calcium concentration. The measured value of: 9.093 wt.% Ca (corresponding to approximately 12.72 wt.% CaO) indicates a calcium-rich high-temperature glaze system. Calcium acts as an effective flux, lowering melting temperatures and promoting formation of a transparent glassy phase during firing. The glaze also contains: moderate potassium content; detectable manganese; low iron concentration; extremely low lead content. The lead concentration of only 26 ppm confirms that the glaze belongs to a fundamentally lead-free technological system consistent with high-fired porcelain production. Iron concentration of approximately 0.76% Fe₂O₃ falls within the compositional range capable of contributing to the characteristic bluish-green optical appearance of Qingbai glazes when combined with reducing kiln atmospheres. 7. Ceramic Body Composition The body exhibits elevated levels of aluminum and silica together with comparatively low calcium concentrations. The calculated body composition includes: SiO₂ = 63.10% Al₂O₃ = 26.92% K₂O = 3.33% CaO = 1.42% Fe₂O₃ = 1.53% TiO₂ = 0.217% A particularly informative parameter is the Al₂O₃/SiO₂ ratio: 0.427 This value indicates a highly alumina-rich ceramic body, reflecting the use of refractory clay materials suitable for high-temperature firing. The elevated aluminum content is consistent with porcelain-associated ceramic technologies developed in southern China during the Song period. 8. Technological Interpretation The compositional relationship between glaze and body demonstrates a coherent technological system: A silica-rich, calcium-fluxed glaze. An aluminosilicate ceramic body. Minimal lead content. Controlled iron levels contributing to glaze coloration. High-temperature firing technology. This combination is characteristic of the ceramic engineering principles underlying Qingbai porcelain production. Particularly noteworthy is the strong chemical contrast between glaze and body, confirming intentional technological differentiation rather than chemical homogenization. 9. Archaeometric Significance The present analysis demonstrates that the vessel combines morphological and compositional characteristics associated with the Qingbai ceramic tradition. Key diagnostic features include: calcium-rich glaze; silica-dominated glass phase; alumina-rich ceramic body; very low lead concentration; moderate iron levels; geochemically coherent trace-element assemblage; traditional Qingbai vessel morphology. Together, these data provide a detailed archaeometric characterization of the object and contribute to the growing body of analytical research on Song-period Chinese ceramics. 10. Conclusion Portable XRF analysis of the Qingbai-type ewer produced the following principal results: The glaze contains elevated calcium (9.093 wt.% Ca), indicating a calcium-fluxed high-fired glaze system. The ceramic body contains substantially higher aluminum (14.25 wt.% Al) and lower calcium (1.013 wt.% Ca), demonstrating clear chemical differentiation between body and glaze. Extremely low lead concentrations support classification within a lead-free porcelain technology. Iron concentrations are consistent with the formation of the characteristic bluish-green coloration associated with Qingbai ceramics. The ceramic body exhibits an elevated Al₂O₃/SiO₂ ratio (0.427), reflecting an alumina-rich refractory composition. The analytical results establish a well-defined technological profile corresponding to the Qingbai ceramic tradition and provide an important contribution to the archaeometric documentation of Song-period Chinese high-fired ceramics. References Unveiling the Secrets of the Song Dynasty Qingbai Porcelain. DOI: 10.1142/S2010135X25500092. Provenance and Firing Technology of Qingbai Porcelain. Analytical Methods. DOI: 10.1039/D5AY01790D. Early Development of Jingdezhen Ceramic Glazes. Archaeometry. DOI: 10.1111/arcm.12539. Provenance of Qingbai Wares from Shabian Kiln. Archaeometry. DOI: 10.1111/arcm.12540. Qingbai and Grey-Greenish Ware Production at Husi. Archaeological and Anthropological Sciences. DOI: 10.1007/s12520-021-01464-4. Smithsonian National Museum of Asian Art. Qingbai Bowl (F1944.47). The Metropolitan Museum of Art. Qingbai Vase (26.292.87).