The plain white Tz´ŭ Chou wares of the Sung period, which favourably compared with the Ting porcelain, have been identified in a few instances only by peculiarities of shape. Indeed, it is unlikely that we shall have any other means of discriminating them from the latter ware. But by far the largest group of the Tz´ŭ Chou family consists of the painted wares. Like the rest of the Tz´ŭ Chou pottery which has so far been identified, these have a greyish buff body of porcellanous stoneware usually coated with a white clay slip and covered with a transparent glaze almost colourless, but with a creamy tinge. On this glaze, and sometimes under it, the painters executed rapid, bold, and rather impressionist designs in shades of brown, varying from black to a soft sepia colour. The earliest specimens seem to have been of this kind, and it is certain that this method of decoration was practised in the Sung period, if not earlier.[235] In a few cases the glaze seems to have been omitted, the brown painting appearing on a lustreless white slip; and where the brown or black colour was laid on in broad washes, details were often etched out with a pointed instrument. The black, moreover, when in considerable areas, sometimes developed passages of lustrous coffee brown[236] (due to the presence of iron), such as is seen in the "partridge cups" of Chien yao. It is probable that the Sung Tz´ŭ Chou ware, with its solid ivory white surface, often crackled, and its sketchy floral designs, may have served as a model to the Japanese for the Kenzan style of decoration and the ivory white Satsuma faience. Another style of ornament, which may date from Sung times, and is certainly common on later wares, consists of a broad band of floral scrolls, with large lily or aster flowers, enclosed by smaller zones of floral pattern or formal designs. Next come the large panels of figure subjects, usually of Taoist sages, or birds and animals in foliage, enclosed by bands of formal ornament or floral scrolls. In some cases a beautiful pale blue glaze of turquoise tint covers this class of ornament (Plate 32, Fig. 1), strangely recalling the Persian and Syrian pottery with still black paintings under a turquoise glaze. Indeed, it was a common error a few years back to class the stray specimens of this type as Persian; but a comparison with the brown-painted Tz´ŭ Chou specimens shows their true origin, and the discovery of a small dish of this kind in a Sung tomb[237] proves the antiquity of this method of decoration in China.