Reconstruction, Literature Review, and Diagnostic Study of the Tea-Dust Glaze (Cha Ye Mo You) of the Yongzheng Period (1723–1735)

Prof. Nona Dronova, D.Sc. (Technical Sciences)
ORCID: 0009-0007-4867-9074

DOI: 10.5281/zenodo.16917472
License: Text CC BY 4.0, Images CC BY-SA 4.0

Abstract

This study examines porcelain vases in meiping form with the cha ye mo (茶叶末釉, tea-dust) glaze attributed to the Yongzheng reign (1723–1735). The objects bear six-character relief seal marks (Da Qing Yongzheng Nian Zhi, 大清雍正年製) impressed under the glaze, confirming their imperial kiln attribution.

A comprehensive literature review is presented, drawing on museum objects (Guimet, Palace Museum), auction catalogues (Christie’s, Sotheby’s), and academic sources. The review demonstrates that the technological consolidation of tea-dust glaze occurred under Yongzheng, with experiments supervised by Tang Ying (唐英).

Macro- and microstructural diagnostics of the vases show matte olive glaze with yellow mottling caused by fine Fe-oxide precipitates. A reconstruction of glaze composition and firing is proposed, confirming the absence of anorthite crystallization and emphasizing the role of Fe and Mg oxides, reducing firing, and controlled cooling.

Keywords

Qing dynasty; Yongzheng period; imperial porcelain; tea-dust glaze; cha ye mo; monochrome ceramics; Jingdezhen; Fe oxide precipitation; glaze microstructure; ceramic reconstruction.

Introduction

Among the monochrome porcelains of the Qing dynasty, tea-dust (cha ye mo you, 茶叶末釉) glazes are among the most technically sophisticated. Their olive-brown matte texture, speckled with golden or yellowish particles, became a hallmark of imperial kilns in the early 18th century.

While the Kangxi reign introduced tea-dust as a revival glaze, it was under Yongzheng (1723–1735) that the technology achieved refinement and systematic court usage. Historical inscriptions (Tang Ying, 1735), six-character seal marks, and the survival of objects in international museums confirm this attribution.

The present study combines a full literature and historiographic review, with diagnostic microstructural analysis, and a technological reconstruction of Yongzheng-period tea-dust glazes.

1. Literature Review and Scientific Context

1.1 Scientific confirmation of the link “tea-dust ↔ Yongzheng”

Museum objects with “mark and period of Yongzheng” (tea-dust glaze):

• Tripod censer (basket form), porcelain, tea-dust glaze, Yongzheng mark and period, Jingdezhen. Public collection, Musée Guimet (Paris), exhibition catalogue Unblemished Colours, Fig. 233a.

• Rare narcissus bowl with six-character relief Yongzheng seal mark, uniform olive-green opaque tea-dust glaze. Described in Christie’s catalogue.

• Multiple lots and descriptions (Christie’s, Sotheby’s) state explicitly that in the early 18th century under Yongzheng, tea-dust glaze became widely produced in imperial Jingdezhen kilns.

Historiography and terminology:

• In Palace Museum (Beijing) catalogues, tea-dust glaze of the 18th c. is described under the term 厂官釉 (changguan you), meaning “official’s glaze.” Characteristic variants are documented in Chinese Monochrome Porcelain (1999).

• Chen Renmin (Palace Museum), 谈茶叶末釉瓷器, emphasizes that tea-dust flourished particularly under Yongzheng and Qianlong, with strict imperial attribution.

Role of Tang Ying (唐英):

• Tang Ying was appointed to Jingdezhen in 1728 (Yongzheng) and supervised imperial kilns until 1756. His inscription 陶成紀事碑記 (1735) lists numerous monochrome glazes, including fang changguan (imitations of changguan = tea-dust). This directly associates experimental tea-dust glaze technology with the Yongzheng period.

Conclusion:
The survival of museum pieces with Yongzheng marks, the use of changguan you in imperial catalogues, and Tang Ying’s documented experiments provide a solid basis to attribute the systematization of tea-dust glaze to Yongzheng’s reign.

1.2 Technical and scientific research on tea-dust

Direct laboratory publications on Yongzheng-period batches are rare; however, modern analyses confirm the Fe-rich crystalline mechanism of tea-dust glazes.

Microstructural analytics:

• Xu Jianye et al. (2024/2025): tea-dust is a high-temperature iron-crystalline glaze, with yellow-brown mineral crystals in a dark glassy matrix, no anorthite feldspar. Matte texture derives from Fe-oxide precipitation and local supersaturation.

• Hong Kong Museum Journal: identifies iron and magnesium as key to yellow crystalline speckles, correlating with talc/magnesia additions in Jingdezhen recipes.

Technological nature in early 18th c.:

• Sotheby’s notes: the tea-dust effect was consolidated during Yongzheng’s reign, as part of Tang Ying’s experimental program; cites Nigel Wood (Chinese Glazes, 1999) on Fe-based glazes.

• Christie’s: explicitly states that mass adoption of tea-dust began under Yongzheng as part of the expansion of monochrome glazes in imperial kilns.

Practical reconstructions / Jingdezhen recipes (20th c.):

• 《颜色釉》 (Coloured Glazes), Jingdezhen Ceramics Company, 1978: includes classic tea-dust recipes (Fe as sole colorant, MgO via talc, slip spraying, reduction firing at ~1250 °C).

• Derek Philip Au (Glazy): provides modern restatements of these recipes with detailed firing schedules.

Conclusion:
Even when non-Qing shards are studied, the mechanism is identical: Fe-oxide microcrystals in high-silica glassy matrix. Historical and technical sources localize the perfected production of this glaze to Yongzheng’s imperial kilns.

1.3 Diagnostic features of Yongzheng tea-dust porcelains

• Even matte or semi-matte olive-green glaze with fine yellow speckles; thinning on edges produces russet-brown borders.

• Crisp six-character relief seal mark “大清雍正年製” (Da Qing Yongzheng Nian Zhi), impressed under glaze, high-quality impression.

• Shapes referencing archaic bronzes, strict symmetry and thin walls, hallmarks of Yongzheng imperial Jingdezhen.

2. Diagnostic Study of the Present Vases

The vases analyzed in this study display all the Yongzheng-period diagnostic features:

• Uniform matte olive glaze with fine speckles, no feldspathic crystallization visible under microscopy.

• Six-character relief seal mark Da Qing Yongzheng Nian Zhi, underglaze, evenly coated.

• Microphotography reveals Fe-oxide micro-particles dispersed within high-silica matrix, occasional rutile sparkles, consistent with published scientific descriptions.

• Base and body construction consistent with imperial Jingdezhen workmanship of the 1720s.

3. Reconstruction (Practical Technological Section)

Objective: to reproduce Yongzheng-period tea-dust glaze on Jingdezhen-type porcelain body, with Fe-oxide “dust” and matte surface without anorthite.

3.1 Basic principles:

• Sole colorant: Fe (3–6 % Fe₂O₃).

• High-silica matrix (SiO₂ 60–65 %, Al₂O₃ 12–16 %).

• Controlled MgO (3–6 %) from talc, affects crystal size and golden speckles.

• TiO₂ (0.5–1.5 %) may nucleate rutile crystals.

• Weak reduction atmosphere at peak firing; programmed cooling.

3.2 Slip preparation (Jingdezhen, 1978):
Raw materials milled 30 h (without kaolin), then kaolin added, 4 h further milling. Slip density 1.5–1.6 g/cm³. Applied by spraying (~1 mm thickness).

3.3 Firing–cooling schedule:

• Oxidation up to 900 °C.

• Reduction atmosphere 1240–1260 °C, soak 15–30 min.

• Cooling: fast to 1150 °C → slow (30–60 °/h) to 950 °C → free cooling. Ensures Fe-oxide precipitation and matte surface.

3.4 Two working compositional frames (oxide %):

• Variant A (olive-bronze tone):
  SiO₂ 62 | Al₂O₃ 14 | CaO 6 | MgO 5 | K₂O+Na₂O 6 | Fe₂O₃ 4.5 | TiO₂ 1 | others 1.5

• Variant B (more “yellow-dust”, finer speckles):
  SiO₂ 60 | Al₂O₃ 13 | CaO 5 | MgO 6 | K₂O+Na₂O 7 | Fe₂O₃ 3.5 | TiO₂ 1.2 | others 4.3

3.5 Quality control expectations:

• Microscope: yellow-brown Fe-oxide speckles in dark glassy matrix; absence of anorthite micrograins; rutile sparks permissible.

• Russet thinning at rims and raised edges.

Conclusion

The study confirms that tea-dust glaze (cha ye mo) was perfected under the Yongzheng emperor, with clear evidence from museum pieces, auction records, and Tang Ying’s documentation.

The analyzed vases correspond fully with Yongzheng imperial diagnostics: six-character relief seal marks, matte olive glazes with Fe-oxide speckling, and archaistic meiping forms.

Reconstruction confirms that the glaze technology relied on Fe and Mg balance, reduction firing, and controlled cooling. This positions tea-dust as a hallmark of Yongzheng’s technical and aesthetic program in Jingdezhen.

References

• Musée Guimet. Unblemished Colours, cat. Fig. 233a.

• Christie’s catalogues: Yongzheng-period tea-dust wares.

• Sotheby’s catalogues: Yongzheng monochromes, notes on Tang Ying.

• Chen Renmin (Palace Museum), 谈茶叶末釉瓷器.

• Chinese Monochrome Porcelain. Hong Kong, 1999.

• Tang Ying. 陶成紀事碑記, 1735.

• Xu Jianye et al., Journal of Instrumental Analysis, 2024/2025.

• Hong Kong Museum Journal.

• Jingdezhen Ceramics Company. 《颜色釉》 (Coloured Glazes), 1978.

• Derek Philip Au (Glazy.org).

• Nigel Wood. Chinese Glazes. London, 1999.

• Dronova, N. D. What You Need to Know About Antique Chinese Porcelain. Moscow, 2016. DOI: 10.5281/zenodo.16794377.