Shufu (Luan bai) wares

Yingqing (qingbai) glaze was first introduced during the Northern Song period and was very popular during the Song period and continued to be produced during the Yuan dynasty. In yingqing glaze, the glaze ash proportion in the glaze is high. Glaze ash is rich in calcium and magnesium oxide, both of which are fluxing agent which lower the melting temperature of glaze. Hence, yingqing glaze has low viscosity and the glaze application is thin to prevent overflowing problem. There is minimum unmelted quartz particles in the glaze and hence looks transparent and shows its clear and light bluish tone well.

During the Yuan dynasty, a new glaze with reduced glaze ash proportion of 10% as compared with about 30% in Yingqing glaze was introduced. Because this type of glaze has a higher viscosity , the glaze application can be thicker. The reduction in the fluxing agents also resulted in more un-melted quartz particles and some fine silicia in the glaze stone remain un-dissolved. Hence, they cause scattering of light and the glaze looks opaque and matted with a softer white or white/light bluish colour tone. The term luan bai meaning goose egg white was used to describe such colour tone. Most of the vessels, consisting of bowls and dishes, using this glaze formula were made in Hutian kilns which were located outside Jingdezhen, Jiangxi province. Some of the bowls and dishes have moulded relief motif and the chinese two chinese characters shu fu meaning "Privy council". Hence, such glaze type wares were also termed shufu wares. Besides shufu, other characters included "tai xi" meaning great happiness and "fu lu" meaning good fortune and emolument could be found. However, majority have just either plain or moulded relief motif of flowers, dragon or phoenix. Such vessels are typically more thickly potted and for the bowls/dishes, there is pooling of glaze at the inner and outer mouth rim.

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Recently, there was a shipwreck discovered near Bali in Indonesia with cargo consisting of many shufu wares. I have selected some examples of dishes and bowls to show the varying glaze tone and look. The colour could could range from sugary white to slight whitish light bluish tone. Some have more transparent glaze but still share the common charateristics of form, thick glaze which pooled at the rim. Possible reasons for the greater transparency could be such pieces were fired at a higher temperature or a higher than usual proportion of glaze ash. Hence, despite such differences, essentially they should still be classified as shufu wares.

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The below centre dish has a thinner and more transparent glaze than those on usual shufu wares. The form is the typical shufu type and it still has the pooling of glaze at the rim. I am of the view that this is a unsuccessfully made piece shufu dish. The potters aspired to a glaze that is thick and matted as shown on the majority of typical shufu wares. This particular piece revealed a dirty tone body especially where the glaze is thin. Nigel Wood in his book "Chinese Glazes" noted that the shufu porcelains "were made from the new albeite-rich body stone mixed with added kaolin... Despite the changes the shufu bodies are actually less pure than the earlier yingqing wares - due to the the higher titania contents of the shufu clays, -- and it is possibe that the semi-opaque shufu glazes were developed to disguise this fact".

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The early Yuan blue and white has a shufu type glaze. Analysis of the glaze on later Yuan blue and white shows that the glaze ash has been increased again and the final proportion is somewhere between shufu and Yingqing. It has a more transparent and clearer colour tone. The ash portion cannot be the same as Yingqing glaze as it's low viscosity would cause greater flow of the glaze and would cause the blue cobalt to spread and blur the motif.

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