Jianzhan: A Starry Sky Within a Cup | The Imperial Art of Song Dynasty
Jianzhan is one of the eight great porcelains of China’s Song Dynasty. Named after its place of origin, Jianyang in Fujian Province, it is thus called Jianzhan. During the Song Dynasty, Jianzhan served as the imperial tea ware for the royal family.
The glaze of Jianzhan is predominantly black,featuring patterns such as hare’s fur, oil spots, yohen (iridescent starlight), and partridge feathers. The hare’s fur patterns are as fine as rabbit hair, the oil spots resemble droplets of oil, and the yohen patterns are as dreamlike as the cosmic starry sky. The patterns on every single Jianzhan are truly one of a kind.
The glaze of Jianzhan falls under the category of ancient Chinese crystalline glazes. During the firing process, due to the varying kiln temperatures and atmospheres in different positions within the kiln, the glaze transforms into a variety of naturally bizarre and fascinating patterns. This kind of pattern, generated by the natural changes of the glaze itself rather than being artificially controlled through colored glazes, is referred to as “kiln transformation”. Kiln transformation is accomplished in one continuous process: entering the kiln in a single color and emerging with thousands of variations. Whether successful or not, there is only this one chance.
The birth of every Jianzhan typically goes through thirteen production processes: mineral selection, porcelain ore crushing, elutriation (washing and sorting), batching, aging, pug milling, clay kneading, throwing (wheel-forming), trimming, bisque firing, glazing, kiln loading, and firing. These thirteen procedures truly test the craftsman's skill, patience, and perseverance.
1.Premium Clay Selection
Clay selection and mineral sourcing: Unique local clay from the Shuiji area of Jianyang, featuring high iron content, along with red clay and high-temperature clay, is selected as the body material. Additionally, hematite and similar minerals are chosen as the raw materials for the glaze.
2.Clay Preparation
Elutriation and filtration: The crushed clay and minerals are stirred with water and passed through a sieve to filter out impurities. The resulting slip is then left to stand and settle, separating the pure clay and glaze materials.
Batching: The materials are blended according to different types and proportions to finalize the formulas for the body and the glaze, meeting the specific requirements for various glaze colors and body textures.
Mineral crushing: The selected porcelain and glaze minerals are crushed using mechanical or water-powered pestles to break them down into fine particles, facilitating subsequent processing.
Aging: The filtered clay and glaze materials are stored in a dark, unventilated environment to age naturally for a period of time. This process enhances the strength, uniformity, and plasticity of the clay.
Pug milling and kneading: The aged clay undergoes pug milling to eliminate any trapped air, ensuring a completely uniform consistency. It is then kneaded into appropriately sized blocks, ready for shaping.
3.Shaping and Trimming
Throwing: Using techniques such as pulling, pinching, and hollowing by hand, the craftsman shapes the kneaded clay into pre-designed forms, creating different bowl shapes such as wide-mouthed, everted-rim, inverted-rim, and constricted-rim vessels.
Trimming: After throwing, the rough blank is trimmed on the wheel to achieve a uniform thickness and a neat, aesthetically pleasing shape. Specific areas such as the foot wall, foot edge, and rim are refined to meet the design requirements.
4.Bisque Firing and Drying
Bisque firing: The trimmed body is subjected to bisque firing, which involves a pre-firing at a relatively low temperature (generally around 750℃) to increase the hardness and strength of the body.
Drying: After bisque firing, the body must undergo a drying process. This can be achieved through natural air drying or by using drying equipment to completely evaporate any residual moisture within the body. This brings the body to the proper level of dryness, fully preparing it for glazing.
5.Glazing
Glaze preparation: According to the formula, natural iron-rich glaze minerals, plant ash, and other raw materials are mixed and ground to prepare a suitable glaze slip. Parameters such as the concentration and viscosity of the slip are carefully controlled to ensure the fluidity and adhesion of the glaze.
Glaze application: Methods such as dipping, brushing, or pouring are employed to apply the glaze slip evenly onto the surface of the body. Jianzhan typically adopts the "half-glazing" technique, where the glaze covers most of the body, but the outer lower section near the foot is left unglazed. This prevents the glaze from flowing and sticking to the kiln shelf at high temperatures.
6.Kiln Loading and Firing
Kiln loading: The glazed bodies are carefully loaded into the kiln. Based on the type of kiln (such as a wood-fired, electric, or gas kiln) and the specific firing techniques, the positions and arrangement of the bodies are strategically planned to ensure they heat evenly during the firing process.
Firing: This is the most crucial stage in the making of Jianzhan, requiring the pieces to be fired at high temperatures between 1200℃ and 1300℃. Throughout the process, the craftsman must closely monitor changes in the kiln temperature and precisely control the timing, extent, and frequency of the reduction atmosphere. This precise control triggers the necessary chemical reactions within the glaze, ultimately forming the unique patterns and glaze colors.
7. Unloading and Inspection
Unloading: Once the firing is complete, the kiln is left to cool down naturally. After the temperature drops to a safe and suitable level, the kiln door is opened, and the finished Jianzhan pieces are carefully taken out.
Inspection: The unloaded Jianzhan pieces undergo a rigorous quality check. Any substandard pieces with deformations, cracks, or glaze flaws are weeded out. Only those that pass this strict inspection are allowed to enter the market or become part of a collection.
About Vivid Ceramic: Crafting Timeless Art with Passion
Vivid Ceramic is a premium artisan studio specializing in handcrafted ceramics and specialty glazes. Our team of professional ceramicists combines years of technical expertise with a lifelong love for craftsmanship to create functional art for the modern home. From our signature Crystalline Glaze collections to traditional Jian Ware (Jianzhan), we are committed to preserving the beauty of ceramic heritage while pushing the boundaries of innovation.