Note: This is a very rare example of this type of Yongle jar with tianbai, 'sweet white', glaze. A small number of these globular jars with loop handles on the shoulder are known decorated with underglaze blue lotus scrolls or floral sprays, but no other white example appears to have been published. The underglaze blue examples are of precisely the same form and size, and their bases are unglazed, as is the base of the current white example. An underglaze blue example with lotus scrolls excavated in 1994 from the Yongle strata at Dongmentou, Zhushan, Jingdezhen is illustrated in Imperial Hongwu and Yongle Porcelain Excavated at Jingdezhen, Chang Foundation, Taipei, 1996, pp. 208-9, no. 73. (Fig. 1)

A blue and white example, with the same lotus scrolls as the excavated example, in the collection of the Palace Museum, Beijing, is illustrated in The Complete Collection of Treasures of the Palace Museum - 34 - Blue and White Porcelain with Underglaze Red (I), Hong Kong, 2000, p. 46, no. 44. The Beijing Palace Museum example has a low cylindrical cover with bud-shaped finial, and it is likely that all these small jars originally had covers, which could be tied in place using the loop handles on the shoulders of the vessels. Also in the Palace Museum, Beijing, is a slightly larger Yongle globular jar of similar shape and with underglaze blue floral sprays around the body illustrated in Gugong bowuyuan zang - Mingchu qinghua, vol. 1, 2002, p, 54, no. 23. While of similar shape to the previous example, the cover of this jar has completely vertical sides, while the previous example splayed slightly towards the rim. The Shanghai Museum also has one of the smaller Yongle globular jars, decorated in underglaze blue, illustrated by Wang Qingzheng in Underglaze Blue and Red, Hong Kong, 1987, no. 50. This jar is decorated with four floral sprays. It no longer has a cover.

Although no tianbai-glazed globular jar of this form appears to have been published, a small tianbai-glazed ewer of similar form excavated in 1983 from the early Yongle stratum at the Imperial kilns at Jingdezhen is illustrated in Imperial Porcelain of the Yongle and Xuande Periods Excavated from the site of the Ming Imperial Factory at Jingdezhen, Urban Council, Hong Kong, 1989, pp. 122-3, no. 20. The body of the ewer has a similar profile to the jar, it has an unglazed base, and has loop handles on the shoulder, although the ewer has four handles, rather than two. It also has the addition of a strap handle and a curved spout. It seems likely that the ewer would originally have had a cover similar to one of the Beijing blue and white jars.

The distinctive tianbai 'sweet white' glaze, seen on the ewer and on the current jar, appears to have first been used on fine imperial porcelains of the Yongle reign. Indeed, it is porcelains with this type of glaze that predominate among the finds from the early Yongle stratum at Jingdezhen. The 'sweet white' glaze is quite different from earlier white glazes as it contains a mass of very tiny bubbles. These have two main effects. Firstly, some of them burst on the surface of the glaze leaving minute holes, like pin-pricks, which give the glaze a slight 'orange-peel' effect, and makes it appear glossy, rather than glassy. Secondly the tiny bubbles held within the glaze refract and scatter the light, giving the glaze a soft, lustrous, appearance that has been likened to white jade. The body of these tianbaiporcelains was also very fine and white, and could be fired at a high temperature which enhanced its translucency. Such porcelains seem to have especially appealed to the Emperor Yongle, who was known for his love of white, and who on one occasion rejected most of the gifts offered to him but retained only those items made of white jade.

The name tianbai does not seem to have been used in the 15th century, but appears in the late 16th century in the Shiwan gan zhu by Huang Yizheng, who refers to zong yan tian bai - bristle hole sweet white. The bristle holes were presumabley the tiny pin-prick holes made by the burst bubbles, which were no wider than a hair's breadth. The choice of the term 'sweet white' may have referred to refined white sugar. In earlier periods the sugar used in China was brown or black, but in the Jiajing reign (AD 1522-66) the way to refine and make white sugar was discovered, and this new white sugar became very popular among the elite classes. It is therefore possible that Huang Yizheng had fine, white sugar in mind when he used the phrase tianbai.