XRF CHARACTERIZATION OF A LAVENDER-GLAZED VASE WITH POETIC INSCRIPTION AND BIRD DECORATION: CHEMICAL COMPOSITION OF AN EXPERIMENTAL MONOCHROME GLAZE

Abstract This paper presents the results of portable X-ray fluorescence (pXRF) analysis of a decorative vase covered with a lavender monochrome glaze and decorated with poetic calligraphy and bird motifs. The investigation was conducted using portable X-ray fluorescence spectroscopy on the glazed surface of the vessel. The analytical results reveal a silica-rich calcium-bearing glaze system containing cobalt, manganese, iron, barium, and strontium. Particularly noteworthy is the combination of cobalt (563 ppm), manganese (990 ppm), iron (3370 ppm), and barium (4220 ppm), which may be regarded as a characteristic chemical assemblage contributing to the formation of the unusual lavender coloration of the glaze. The compositional data indicate the use of a sophisticated high-temperature decorative glaze technology specifically designed to achieve a distinctive monochrome visual effect. Keywords: monochrome glaze, lavender glaze, Chinese ceramics, archaeometry, XRF, cobalt, barium, manganese, high-fired glaze. 1. Introduction Monochrome glazes occupy a special position in the history of Chinese ceramic art. Unlike painted ceramics, the aesthetic effect in monochrome wares is achieved not through pictorial decoration but through the complex interaction of glaze chemistry, firing conditions, and the optical properties of the vitreous phase. Among the rarest varieties are lavender, lilac, and grey-violet glazes, the production of which required careful control of both coloring agents and fluxing materials. The present study examines the chemical composition of a decorative vase featuring a lavender monochrome glaze enhanced by poetic calligraphy and bird imagery. 2. Description of the Object The investigated object is a decorative ceramic vase covered with a monochrome glaze displaying a complex lavender coloration. The artistic decoration includes: a poetic calligraphic inscription; bird motifs; a monochrome glazed ground; a glossy semi-translucent surface. The glaze exhibits subtle chromatic transitions ranging from pale lilac to grey-blue tones. The surface displays a pronounced vitreous luster characteristic of well-developed high-fired glaze systems. 3. Materials and Methods The investigation was performed using portable X-ray fluorescence spectroscopy. Instrument: Geochem (3-Beam) Extra Analytical conditions: acquisition time: 30 seconds; Geochem Extra analytical mode; non-destructive in situ measurement. A glazed surface area of the vase was selected for analysis. 4. Analytical Results Table 1. Principal Chemical Components of the Glaze Element Concentration Si 20.35% Al 2.83% Ca 4.162% K 1.270% S 2.371% Fe 3370 ppm Mn 990 ppm Co 563 ppm Ba 4220 ppm Sr 180 ppm Rb 226 ppm Pb 803 ppm The analytical results demonstrate a glaze system characterized by silica and calcium enrichment combined with relatively low aluminum concentrations. 5. The Role of Calcium in the Glaze System Calcium represents the principal fluxing component of the investigated glaze. The measured concentration is: Ca = 4.162 wt.% Calcium promotes the formation of a transparent vitreous structure and improves glaze fluidity during firing. Together with silicon and potassium, calcium forms the fundamental framework of the high-temperature silicate glaze system. 6. Cobalt and the Formation of Lavender Coloration The presence of cobalt is one of the most significant features of the analytical results. The measured concentration is: Co = 563 ppm Cobalt is among the most powerful colorants used in ceramic glazes. Even at relatively low concentrations, cobalt is capable of producing blue, violet, and lavender hues. In the present glaze, cobalt is not present in isolation but occurs together with iron and manganese, forming a complex coloring system. 7. Iron, Manganese, and Chromatic Effects In addition to cobalt, the glaze contains: Fe = 3370 ppm; Mn = 990 ppm. Both iron and manganese exert an important influence on glaze coloration. The simultaneous occurrence of: cobalt; iron; manganese; creates a complex chromatic system capable of generating transitions between blue, grey, violet, and lavender tones. This chemical combination provides a plausible explanation for the distinctive lavender appearance of the glaze. 8. Barium as a Technological Component One of the most unusual findings of the investigation is the elevated concentration of barium. The measured value is: Ba = 4220 ppm Barium occurs in considerably higher concentrations than most other trace elements detected in the glaze. Its presence suggests the use of specific mineral raw materials or specialized glaze ingredients. Together with calcium and strontium, barium forms a distinctive alkaline-earth element assemblage within the glaze. 9. Technological Characteristics of the Glaze The chemical composition of the investigated surface reveals several notable technological characteristics: A silica-rich vitreous matrix. Calcium as the principal fluxing component. Cobalt functioning as a chromophoric element. Manganese and iron contributing to color modulation. Elevated barium content. Relatively low lead concentration. The combination of these components forms a sophisticated decorative glaze system specifically engineered to produce a rare monochrome visual effect. 10. Archaeometric Interpretation The investigated vase represents a significant example of an artistic monochrome glaze technology. The most diagnostically important components of the glaze are: cobalt; manganese; iron; barium; calcium. The lavender coloration can be understood as the result of interaction among multiple chromophoric elements dispersed within a single vitreous phase. The chemical composition demonstrates a deliberate adjustment of raw materials aimed at achieving a refined decorative monochrome appearance. 11. Conclusion The XRF investigation of the lavender-glazed vase established the following characteristics: The glaze contains significant concentrations of silicon (20.35 wt.%) and calcium (4.162 wt.%). Cobalt (563 ppm), manganese (990 ppm), and iron (3370 ppm) are present as important chromophoric elements. The most unusual component detected is barium (4220 ppm). The coloration system is based on the combined presence of cobalt, manganese, and iron. The glaze represents a sophisticated high-temperature monochrome composition developed to produce a distinctive lavender visual effect. General Conclusion: The chemical composition of the investigated glaze reflects the use of a specialized decorative technology based on a multi-element coloring system. The association of cobalt, iron, manganese, calcium, and barium creates a unique archaeometric signature that characterizes the artistic lavender glaze of this vessel and documents an advanced approach to monochrome ceramic coloration.