Glaze-over-glaze, underglaze, and a combination of both techniques are common in colored porcelain production. Low-temperature overglaze and high-temperature underglaze have distinct advantages and drawbacks.
There are many varieties of colored porcelain in the Ming and Qing dynasties. Due to differences in production techniques, materials, and firing temperatures, the produced colored porcelain exhibits unique style characteristics. They can be classified into three major categories based on production techniques: underglaze decoration, overglaze decoration, and a combination of both techniques.
Underglaze decoration involves directly decorating and painting on the body of the porcelain with pigments, then covering it with a layer of transparent glaze, and firing it at high temperatures in the kiln. The prominent features of underglaze decorated porcelain are that the patterns are resistant to wear, they do not fade during use, they are lead-free and non-toxic, and the surface of the object is smooth. The main varieties of underglaze decorated porcelain in the Ming and Qing dynasties are blue and white, and underglaze red.
Overglaze decoration can be further divided into low-temperature overglaze and high-temperature overglaze. Low-temperature overglaze involves painting various colors on the already fired porcelain glaze surface and then firing it again at temperatures between 600°C and 900°C to create raised decorations. The main varieties include overglaze enamels in red and green, overglaze multicolored decorations, famille rose, three-color overglaze, and ink color decoration. High-temperature overglaze, on the other hand, involves painting on the glazed surface of the unfired body, then firing it once at temperatures of 1200°C to 1300°C. This kind of overglaze decoration is sometimes referred to as “glaze-integrated colors” because the colors and glaze melt together at high temperatures, giving the impression that the colors are within the glaze.
The combination of overglaze and underglaze techniques involves first painting partial decorations on the body of the ceramic, applying a transparent glaze, firing it at high temperatures to create a semi-finished product, and then painting additional decorations on the glazed surface. Afterward, it undergoes a low-temperature firing process to achieve a perfect integration of overglaze and underglaze decorations. This technique mainly includes blue and white overglaze enamels and doucai.
The main differences between overglaze and underglaze decoration are:
In terms of painting materials, underglaze decoration has a richer pigment content compared to overglaze decoration.
In terms of manufacturing processes, underglaze decoration involves a single high-temperature firing, which simplifies the ceramic production process and reduces costs, while overglaze decoration typically requires two firings, increasing the production cost.
In terms of texture, underglaze decorations are more resistant to wear and are harmless to humans. Modern science has shown that the pigments used in low-temperature overglaze decoration contain harmful substances such as lead.
In terms of decorative effects, underglaze decorations, whether blue and white or underglaze red patterns, are elegant, clean, lovely, and exhibit traditional Chinese ink painting artistic effects that appeal to both refined and popular tastes. On the other hand, overglaze decorations are characterized by vibrant and magnificent colors, especially in enamel colors and famille rose, which attract high appreciation from literati, collectors, connoisseurs, and enthusiasts for their exquisite and delicate craftsmanship
