Vessels covered in this unusual glaze colour known under various terms, such as salan (speckled blue), xuehualan (snowflake blue) or qinjinlan (metallic blue) are special and rare. While the term qinjinlan tends to be preferred in China, in the West these wares are better known by the term snowflake-blue. The earliest pieces covered in this attractive glaze are known from the Ming Dynasty, with a number of Xuande mark and period examples extant to this day. It is said that the cobalt-blue glaze mixture was blown directly onto the already fired but unglazed porcelain body, which was then fired at a low temperature (around 800-900 degree celcius) like cobalt-blue glazes found on Tang period earthenwares. This technique as well as the mottled effect and the varied range of tones from a light turquoise blue to an intense lapis lazuli tone are unlike those of any other glazes developed in the early Ming dynasty. In fact, this glaze represents one of the most spectacular and surprising developments of the Ming imperial kilns in the Xuande period, and appears to have been one of the most difficult to fire successfully. The majority of wares covered in this glaze that have survived intact are bowls, however, recent excavations at the Jingdezhen imperial kiln site have revealed extensive experimentations during the Xuande period with this kind of glaze on a wide repertoire of shapes that include dishes, stembowls, narcissus bowls, jars and bowls. See a Xuande mark and period bowl in the Capital Museum, Beijing, illustrated in Shoudu Bowuguan cang ci xuan (Selection of Porcelains from the Capital Museum), Beijing, 1991, pl. 104; and another bowl with flared rim included in the Special Exhibition of selected Hsuan-te Imperial Porcelains of the Ming Dynasty, National Palace Museum, Taipei, 1998, cat. no. 131.
The revival of the snowflake-blue glaze during the Qing dynasty, under the reign of the Yongzheng Emperor, reflects the emperor’s impeccable taste and his fondness for ancient historical glazes. Under his reign, glazes imitating the five official wares of the Song dynasty were created, along with the present example after Ming prototypes. Yongzheng potters working in the Imperial kilns at Jingdezhen, Jiangxi province, showed their high level of skill by ‘re-creating’ aspects of early vessels and closely following models available from the court collection.
For examples of snowflake-blue glazed wares, see a tripod censer included in the exhibition Qingdai danse you ciqi tezhan, National Palace Museum, Taipei, 1981, cat. no. 39; a garlic-mouth bottle vase and a water vessel in the form of a pomegranate illustrated in Gugong Bowuyuan cang, Qingdai yuyao ciqi [ Porcelains from the Qing dynasty imperial kilns preserved in the Palace Museum], vol. 1, Beijing, 2005, pl. 126 and pl. 127 respectively; and a large globular form jar published in Kangxi. Yongzheng. Qianlong. Qing Porcelain from the Palace Museum Collection, Hong Kong, 1989, pl. 118.