Copper Red Monochrome Glazes in Chinese Porcelain: From Early Experiments to Kangxi Perfection

Author: Prof. Nona Dronova, D.Sc.ORCID: https://orcid.org/0009-0007-4867-9074 Abstract This study examines the technological and artistic characteristics of Chinese copper-red monochrome glazes, focusing on two historically significant types: Ox Blood (牛血紅, niu xue hong) and Horse Liver (馬肝紅, ma gan hong). These glazes, achieved through precise control of copper oxide chemistry and reducing kiln atmospheres, reached their peak refinement during the Kangxi period (1662–1722). As a case study, we present a double-gourd vase with a deep copper-red glaze of the Horse Liver type, bearing a six-character Kangxi mark in underglaze blue. Macro- and microstructural observations confirm the authenticity and imperial workshop origin of this example. Keywords Kangxi period, Qing dynasty, copper red glaze, Ox Blood, Horse Liver, Langyao, Jingdezhen, reducing firing, microstructure, porcelain authentication, imperial kiln, double gourd vase 1. Historical Context Copper-red monochrome glazes represent one of the most technically demanding and aesthetically celebrated achievements in Chinese porcelain. Introduced experimentally in the late Tang and Song dynasties, their production reached a new level of stability and sophistication in the imperial kilns of Jingdezhen during the Kangxi reign. The rarity of successful firings, due to the volatile chemistry of copper under reduction, made these wares highly valued both at the Qing court and in later collections worldwide. 2. Principal Types of Copper Monochrome Glazes 2.1. Ox Blood (牛血紅 / niu xue hong) Colour: deep, vibrant ruby red, sometimes with subtle tonal gradients. Colour mechanism: reduction of CuO to Cu₂O under low-oxygen firing. Surface: even, glossy, with possible transparent pooling near the footrim. 2.2. Horse Liver (馬肝紅 / ma gan hong) Colour: darker, subdued, velvety burgundy with purple-brown overtones. Features: often exhibits pronounced natural crackle (craquelure) and soft tonal transitions. Favoured in late Ming and Kangxi for dignified, sober vessel aesthetics. 2.3. Apple Red (蘋果紅 / ping guo hong) Lighter red, evenly distributed pinkish-red tones. More common in smaller forms, such as bowls and small vases. 2.4. Special Effects and Variations Langyao (郎窯紅): Ox Blood with white or pale rings at the mouth or foot, due to glaze thinning and pooling. Flambé (窯變 / yao bian): multicolour streaks and iridescence, more typical of Yongzheng and Qianlong production. 3. Technology of Production 3.1. Glaze Composition Pigment: copper oxide (CuO) as primary chromophore. Transparent silica-lead glaze matrix. Additional fluxes to lower melting point and stabilise colour. 3.2. Firing Atmosphere Strictly reducing (oxygen-deficient) conditions. Firing temperature: ~1260–1280°C. Charcoal fuel ensured strong reduction in Jingdezhen kilns. 3.3. Colour Formation Reduction of CuO to Cu₂O produces the characteristic red. Localised variations in kiln temperature and oxygen content produce tonal gradients and depth. 4. Diagnostic Features of Authentic Kangxi Copper-Red Glazes Microbubbles within the glaze, visible under magnification, caused by vigorous melting during high-temperature firing. Natural craquelure from thermal expansion mismatch between glaze and porcelain body. Smooth colour transitions from saturated areas to paler rims. Footrim with unglazed biscuit body, ash patina, and no modern grinding marks. Underglaze blue mark with cobalt pigment granules visible under magnification. 5. Case Study: Double-Gourd Vase with Horse Liver Glaze, Kangxi Period Specifications: Height: 22 cm Form: double gourd (雙聯壺 / shuang lian hu) Glaze: deep, complex copper-red with burgundy tonality and pronounced natural craquelure Mark: six-character Kangxi reign mark (大清康熙年製) in underglaze blue Microstructure: uniform microbubble distribution, zonal tonal variation, white unglazed ring at footrim Comparative Examples: Palace Museum, Beijing — Kangxi Horse Liver double-gourd vase, similar tonality and microstructure. Metropolitan Museum of Art, New York (Acc. No. 29.100.642) — Ox Blood glaze, Kangxi period, with comparable form and glaze pooling effects. State Museum of Oriental Art, Moscow — Kangxi Horse Liver vase with identical craquelure patterning. 6. Conclusion Copper-red monochrome glazes of the Kangxi period represent the pinnacle of Jingdezhen technical artistry. Ox Blood and Horse Liver are closely related in chemistry but distinct in visual character. The examined vase exhibits all hallmarks of authentic Kangxi imperial production in terms of glaze structure, colour depth, firing evidence, and mark execution, supporting its attribution to the first third of the 18th century.