Chinese ceramics have gained global renown through centuries of evolution, closely linked to continuous innovation in production techniques. This article outlines key ceramic-making processes.
**Wheel Throwing** A traditional method in Chinese ceramic production, wheel throwing involves placing clay on a potter’s wheel (called a ‘lulu’) and using rotational force to shape the material with both hands. This technique forms round vessels like plates and bowls. **Trimming** When the thrown clay reaches a semi-dry state, it is returned to the wheel for surface refinement using knives. This trimming process ensures smooth surfaces and uniform wall thickness. **Foot Carving** After wheel throwing, a 3-inch clay handle remains at the base. Carving this into the final foot ring completes the vessel’s foundation. **Coil Building** As a primitive forming technique, coil construction involves rolling clay into long strips and spiraling them upward according to the desired shape. The interior and exterior are then smoothed by hand or simple tools, often leaving visible coil marks inside finished pieces. **Wheel Manufacturing** Utilizing a wooden wheel with vertical axes rooted in the ground, this method employs rotational energy to shape clay. Originating from the late Dawenkou culture (Neolithic period), wheel-made wares demonstrate remarkable consistency in form and thickness, signaling the emergence of professional potters. **Kiln Firing Techniques** Firing represents the most critical phase in ceramic production, with kiln designs reflecting historical technological advancements. Two primary methods include: – **Upright Firing**: Placing vessels right-side up on supports within saggars – **Inverted Firing**: Firing pieces upside-down on support rings, a technique pioneered by Ding kilns during the Northern Song Dynasty While inverted firing increased output and reduced deformation, it left rim edges unglazed. Both methods required thin-walled constructions to minimize warping, with upright firing eventually being phased out due to rim distortion issues.Stack firing involves stacking multiple ceramic pieces together for firing, with spacers placed between them to prevent fusion. Methods include spur stacking, ring support stacking, overlap stacking, or glaze-scraping stacking—where a ring of glaze is scraped from the interior of a piece, allowing the unglazed foot of the next piece to rest on it. Typically, around ten pieces are stacked layer by layer. This method was prevalent during the Jin Dynasty, offering advantages such as high yield and low cost, though it leaves an unglazed ring on the interior of the pieces.
Different firing methods not only leave corresponding marks on the ceramics but also influence their shapes due to specific technical characteristics. For example, the ‘ring support upward firing’ and ‘ring support downward firing’ methods affected vessel forms. In the early Tang Dynasty, tripod spur spacers were widely used—placed in the center of bowls, with another bowl stacked on top, repeated in layers before being placed in saggars. This left three spur marks on the fully glazed bowl centers. To withstand the weight of multiple layers, bowls were often made with shallow bodies, thick walls, and flat bases. By the mid-to-late Tang Dynasty, the single-firing-per-sagger method was invented. Bowls were adapted to fit individual saggars, leading to a 45-degree slant on the exterior walls. As they no longer needed to support upper layers, flat bases gradually decreased, while disc-shaped bases and wide ring feet became more common. Biscuit firing refers to the initial low-temperature firing (around 750–950°C) of ceramics that require two firings. This process, known as biscuit firing, strengthens the body and increases the success rate before glazing and final firing. Examples of biscuit-fired ceramics include Tang Sancai from Gongxian, Henan; low-temperature lead-glazed pottery from the Cizhou Kiln in Cixian, Hebei during the Song and Jin Dynasties; Jun ware from Yuxian, Henan in the Song Dynasty; and Longquan celadon from the Southern Song Dynasty in Zhejiang. Many renowned ancient ceramics, such as Tang Sancai, Yaozhou ware, Langyao red, Jun red, sky-blue glaze, and certain celadons, underwent biscuit firing before glazing. Unglazed ring refers to the area where a ring of glaze is scraped from the interior of a ceramic piece before stack firing. This technique was popular during the Jin and Yuan Dynasties. Glazing involves applying a slurry of glaze to the surface of a formed ceramic body. The variety of glaze types necessitates different application methods depending on the thickness and shape of the body. Common techniques include dipping, pouring, trailing, brushing, spraying, and sprinkling. Pouring glaze, also known as swing glazing, is suitable for small-mouthed, deep-bodied pieces like bottles and vases. The glaze slurry is poured into the body, swirled to coat the interior evenly, and then excess slurry is poured out. The body is rotated to ensure no glaze remains at the mouth. This process should not exceed two repetitions to avoid bubbles and must be performed quickly to prevent the body from softening. For trailing glaze on small pieces, the item is held directly over a glaze container, and glaze is poured over it, ensuring runoff flows back into the container. For larger pieces, a wire mesh or wooden support is placed inside the glaze container, and the item is positioned on it for glazing. Large pieces typically require two persons working in unison to achieve an even glaze application.Brush glazing, also known as glaze application, involves using a brush or to apply glaze slurry onto ceramic bodies. This method is suitable for small-area applications (such as partial glazing or touch-ups), glaze painting, applying different glazes on the same body, or angular objects like porcelain panel paintings. When brush glazing, attention must be paid to the thickness of different glaze colors and the uniformity on the body. Avoid repeated brushing as it may cause glaze peeling.
Spray glazing, or blow glazing, utilizes a spray gun or atomizer to mist glaze slurry onto the body surface. The number of spraying cycles varies with the glaze type, ranging from a few to seventeen or eighteen times, enabling multi-color glazing and thicker layers. This technique is ideal for large or thin-walled bodies, with thinner application at the bottom to prevent dripping. Uniformity should be checked and touch-ups or base scraping performed as needed. Its advantage lies in achieving consistent internal and external glaze coverage, commonly used for large pieces, thin-bodied ware, and colored glaze products. Originated in Jingdezhen during the Ming Dynasty. Splashed glazing, referred to as twisted glaze or, involves sprinkling another glaze onto a pre-glazed body while rotating it on a turntable or manually turning the piece. It includes full-body and partial splashing. The uniqueness of this method lies in its random artistic effects, producing patterns such as lines, spots, or formations. Source: Five Great Kilns