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Main Author:	NONA, Dronova
Format:	Recurso digital
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Published:	Zenodo 2025
Online Access:	https://doi.org/10.5281/zenodo.16762103
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Abstract: This study presents the first comprehensive microscopic analysis of authentic Doucai glazes on a confirmed Chenghua-period porcelain vase (meiping form). The red copper glaze, green and yellow lead glazes, and underglaze cobalt painting are examined in detail to identify key structural, chromatic, and technological markers of authenticity. These glazes, considered masterpieces of 15th-century Chinese ceramic craftsmanship, have never been successfully replicated in their full complexity despite mass imitation attempts. The documented microphotographs serve as benchmark images for the scientific attribution of original Chenghua glazes. Introduction: This research is of exceptional importance as it represents the first detailed microscopic documentation of authentic Doucai glazes on a verified Chenghua-period porcelain object. The red copper glaze, green copper glaze, yellow sacrificial glaze, and underglaze cobalt decoration exemplify the technological sophistication achieved during the mid-Ming dynasty. The layered glaze structures, the dual firing atmospheres (oxidizing and reducing), and the painterly pigment diffusion cannot be replicated in modern imitations. Red Glaze: <ul> <li> Color: Deep and metallic due to the reduction of copper (Cu⁰). Produced by applying copper pigment over a transparent lead-silicate underglaze, followed by reduction firing in a low-oxygen atmosphere. Any deviation in kiln conditions results in oxidation (producing dull brownish tones) or glaze failure. The color is chemically unstable and depends on precise control of temperature, duration, and oxygen availability. </li> <li> Structure: Features bubbles of varying sizes, metallic reflections, and visible brushstrokes. Diagnostic features include: • Asymmetric gas bubbles in pigment-rich zones • Metallic luster in central areas • Surface or internal microcrystals (Cu₂O, PbSiO₃) • Layered glaze matrix with pigment suspended in depth • Diffused edges blending with adjacent glazes • Brushstroke traces and uneven pigment distribution </li> <li> Diagnostic Value: Authentic red glaze shows non-uniform bubbles, localized luster, deep internal structure, and irregular hand-applied brushwork—all absent in modern fakes. </li> </ul> Green Glaze: <ul> <li> Color: Grass-green with optical depth. Microscopy reveals three-dimensional layering, with pigment diffused within the lead-silicate matrix. </li> <li> Structure: Soft gradients, non-uniform pigment thickness, and reaction-based bubble formation. </li> <li> Diagnostic Criteria: • Irregular color gradients due to natural diffusion • Variation in pigment layer thickness • Asymmetric embedded bubbles • Absence of artificial crackling or uniform coverage </li> <li> Technological Basis: Fired in oxidizing atmosphere; copper remains in Cu²⁺ form, stabilizing the green hue. Contrasts with red glaze, which requires reducing atmosphere (to Cu⁰). Dual-kiln strategies were strictly controlled at imperial kilns in Jingdezhen. </li> </ul> Yellow Glaze: <ul> <li> Color: Lemon-yellow, semi-transparent with optical vibration. Diagnostic microscopy reveals: • Faint phase boundaries between color and base glaze • Microinclusions and small bubbles indicative of low-temperature firing • Irregular light refraction, not reproducible in synthetic yellow glazes • Subtle tonal shifts (lemon–green–ochre), absent in imitations </li> <li> Structure: Hazy texture, flussed zones, and absence of lacquer-like gloss </li> <li> Diagnostic Value: The glaze appears soft, not perfectly transparent, with variable hue and natural internal scattering. Authentic sacrificial yellow glazes never show absolute clarity or synthetic homogeneity. </li> </ul> Underglaze Cobalt Decoration: <ul> <li> Painted before firing, with characteristic "halo" effect. </li> <li> Diagnostic Microscopic Features: • Diffused pigment penetration into clear matrix • Color transitions from deep blue to greyish-blue due to impurities (Mn, Fe) • Soft boundaries and no stencil lines • Bubble-rich lines and flussed dispersion • Absence of surface gloss from post-firing pigment application </li> <li> Literature Correlation: Yin (2020) notes cobalt diffusion and metallic impurities. Hou (2021) highlights thermal integration, edge softness, and absence of modern stamps. </li> </ul> Foot Rim and Porcelain Body: <ul> <li> The so-called “Grandson of the Emperor’s Foot” (term used by collectors) refers to a brownish oxidation zone at the junction of glazed and unglazed areas. It results from late-stage atmospheric variation and volatile component migration (especially iron) during high-temperature firing. Its presence indicates authentic kiln behavior unique to imperial production. </li> <li> The porcelain body is exceptionally thin and translucent. Viewed against light, the underglaze cobalt mark is clearly legible. The base glaze is smooth, lustrous, and precisely transitions from glazed to bare sections. </li> </ul> Full Diagnostic Summary: All expected features of authentic Chenghua-period porcelain are confirmed in this vase: • Pigment diffusion in lead-silicate matrix • Metallic luster in red glaze • Optical depth in green and yellow glazes • Multi-sized gas bubbles • Brushstroke evidence • Lack of artificial crackling • Cobalt halo effects • Oxidized foot rim ("grandson of the emperor") • Underglaze mark legible from below • Thin, luminous body and high-quality base glaze Conclusion: The combination of microstructural and visual evidence confirms the authenticity of this meiping vase as a product of the imperial kilns during the Chenghua reign. The glaze structures, pigment behavior, and firing characteristics correspond precisely with scientific literature (Hou 2021, Yin 2020, Nature Materials 2024). This object constitutes a reference standard for the scientific attribution of Doucai glazes from the 15th century. Keywords: Chenghua, Doucai, copper red glaze, green glaze, yellow glaze, underglaze cobalt, Ming dynasty porcelain, glaze microstructure, kiln atmosphere, pigment diffusion, authenticity 关键词(中文): 成化、斗彩、铜红釉、黄釉、绿釉、钴料、明代官窑、瓷器微观结构、还原气氛、釉层扩散、真伪鉴定   <h2>Appendix: Microphotographic Atlas and Figure Descriptions</h2> <h3>Full Atlas Reference</h3> A comprehensive atlas of microphotographs of the Chenghua-period copper-red glaze can be explored in Nona Dronova's detailed study: <a href="https://www.academia.edu/143317678/Microstructural_Analysis_of_Copper_Red_Glaze_from_the_Chenghua_Period_Meiping_Vase_Form_Part_1_Author" target="_new" rel="noopener">Microstructural Analysis of Copper‑Red Glaze from the Chenghua Period (Meiping Vase Form, Part 1, Author)</a>. <h3>Summary of Microphotographs Included</h3> Figure 1. Duck motif detail: Demonstrates the layered application of red, yellow, green, and cobalt pigments in the Doucai technique, highlighting chromatic interplay and microdiffusion. Figure 2. Blue duck detail: Underglaze cobalt painting with classic “halo” diffusion and tonal transition from dark to lighter blue — diagnostic of genuine Chenghua workmanship. Figure 3. Base with six-character reign mark: “Da Ming Chenghua Nian Zhi” beneath the glaze; finely painted and visible through the thin, translucent porcelain. Figure 4. Imperial foot (“Grandson of the Emperor’s Foot”): Brownish oxidation band at the base, resulting from iron migration in late-stage high-temperature firing (collector’s term: 孫腳). Figure 5. Cobalt halo effect: Underglaze cobalt pigment with diffused, concentric ring structure — a key marker of authentic imperial firing. Figure 6. Green copper glaze diffusion: Shows natural pigment diffusion within the clear glaze matrix, smooth transitions, and embedded bubble inclusions from oxidizing atmosphere firing. Figure 7. Red copper glaze penetration: Depicts diffusion halos, pigment penetration depth, and granulated edge — evidence of carefully controlled reducing atmosphere. Figure 8. Copper red accumulation: Microstructures showing metallic crystallization, micro-bubbles, and copper segregation — hallmark of sacrificial red glaze from Chenghua. Figure 9. Green-over-red stratigraphy: Overlap of green pigment on red glaze with clear phase boundary and embedded bubbles, showcasing multi-color Doucai layering. Figure 10. Copper-red boundary: Dense, vitrified red island in the matrix with blue halo and stratified microstructure — signature of high-temperature reduction firing. Figure 11. Yellow sacrificial glaze: Semi-opaque yellow layer with pigment gradient and fine particle inclusion, characteristic of hand-applied sacrificial glaze with structural depth.

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