by Siyan and Patrick
This week we look at the different styles and techniques of Chinese porcelain, beginning with the choice of layering for the paint and the glaze. Porcelain artists have a very basic choice to make before they begin to paint their pieces. The choice is whether to use 1) Youxiacai 釉下彩, painting under the glaze; 2) youzhongcai 釉中彩, painting in between glazes; 3) youshangcai 釉上彩, painting on the surface of the glaze. While it may seem unimportant, this choice will dictate what colours can be used, the final appearance of the painting, and even the surface texture of the piece. Each method has its own history and uses.
Youxiacai Began during the Song Dynasty. Youxiacai is applied on unglazed porcelain that has not yet been fired or that has only been bisque fired (a low-temperature firing to dry out the clay). It is painted directly on the porcelain body and then is covered with a transparent glaze. It is then fired at a high temperature (usually between 1200-1300°C). The color choices for the painting are limited to those that will do well fired at that high temperature range. Two examples are cobalt blue, used in Qinghua 青花 “blue and white” porcelain, and youlihong 釉里红, a characteristic red that is often paired with cobalt blue. After firing youxiacai porcelain is very smooth, almost like glass. The colour will never fade and is trapped under the glaze.
Youzhongcai Was adopted in the 1970s. Youzhongcai begins by firing a clear glaze over a porcelain body. Paint is then applied to the glazed porcelain, and then another layer of transparent glaze is applied over the paint. The piece is then fired for around 90 minutes at a high temperature of over 1200°C. The advantage of this method is that the short final firing period allows a greater range of color choices and materials than youxiacai, which can only use colors able to withstand a long firing period at very high temperatures. The high temperature still needs to be taken into account as some pigments may change colour at different firing ranges. Youzhongcai also appears glass-like and traps the paint below the glaze. Youzhongcai can appear similar to youxiacai.
Youshangcai Originated during the Ming Dynasty. The porcelain body with a clear glaze is fired first at a high temperature and emerges from the kiln as finished glazed porcelain. The piece is then painted and fired at a lower temperature (between 650-800°C). Most pigments can be fired at this range without losing their colour or quality, and as a result youshangcai can feature a wide range of colours. Because no glaze is applied over the painting, you can feel the texture of the painted area over the porcelain. It is ideal for colourful paintings or patterns with great detail, and is often used for porcelain fine art paintings and vases.
Although most painted Chinese porcelain fall under one of these three categories, more than one of these methods can be used together in one piece. Read our next entry to learn about combining these methods to produce a very special painted porcelain called "Doucai."
This blog entry marks the beginning of our series on Chinese Porcelain; its characteristics, types, glazes and patterns. Before we focus on each of these subtopics, we begin as broadly as possible with 4 basic things you need to know about Chinese porcelain.
1) True Porcelain is impermeable and translucent.
Chinese porcelain manufactured in Jingdezhen is the original “hard paste” porcelain. All true porcelain – excluding bone china – is based on this recipe. The recipe for porcelain is a mixture of the materials kaolin 高岭土and petuntse 白墩子/瓷石 into a clay that is then shaped and fired at around 1300°C and over.
When porcelain is fired at or over 1300°C the petuntse vitrifies (becoming glass-like) and the kaolin provides strength, stability and its characteristic whiteness. Vitrification of the clay is an essential step in the manufacture of porcelain and it is vitrification which makes porcelain translucent and impermeable to water.
Low quality porcelain may be fired cheaply at much lower temperatures than 1300°C and will not undergo this important change. If you shine a light behind true porcelain that is not painted or glazed in an opaque color, you should be able to see the light glow through it. This is one method to check the quality of the material. Another method is checking to see whether unglazed areas of the porcelain object become permanently stained (by tea or dirt, etc.) or whether they can be easily cleaned. True porcelain that is high fired will be impermeable and will not stain under the surface; making it easy to clean. Low fired porcelain and fake porcelain will pick up permanent staining in unglazed areas.
2) Thinner is Better
Thin-walled porcelain is a sign of quality for the simple reason that it is more difficult to make. Very thin-walled porcelain is almost always fully-handmade as it is more difficult – and therefore more expensive – to make it using a machine process. Porcelain not shaped by hand is usually either made by a press or by pouring into a mould. In both cases the soft clay will show damage from this process if it is thin-walled. Imperfections on the surface are common when porcelain is made by pouring the liquified clay into a mould.
3) Beware of Surface Painting on Antiques
Youshangcai 釉上彩 is the practice of painting on the surface of a glazed porcelain object. Youshangcai is perfectly acceptable if used on vases or other decorative objects or if it is from a trustworthy modern studio. The danger comes from the possibility of the paint containing (especially in antique pieces) harmful chemicals or heavy metals. Youzhongcai 釉中彩 (painting in between glazes) and youxiacai 釉下彩 (painting under the glaze) are safer as the paint is contained under the glaze.
4) Form and function are equally important
Porcelain is one of the most versatile materials with which to fashion teaware. It can be shaped into a wide variety of shapes and its thickness can vary from very thick to egg shell thin. With such a versatile material, porcelain teaware can offer the best in terms of comfort, weight and ease of use.
Porcelain should be both beautiful and practical. Porcelain teaware should be comfortable to use, light for its size and feel well-balanced in the hand. Trust your feeling when deciding on a porcelain piece.