Powder-Blue Decoration :
Speckled grounds colours used in combination with masked-out reserves have been used in Chinese ceramics for a very long time, an early example are the Jizhou wares of the Southern Song and Yuan dynasties. The early use of powdered cobalt blue on Chinese porcelain appears to dates the first decades of the 17th century, during the last years of the Ming Dynasty. Chinese export porcelain made for the Japanese market during the reigns of Tianqi (1621-1627) and Chongzhen (1628-1643) sometimes have what the Japanese referred to as `Fukizumi` (Powder blue). Powdered cobalt was blown down a bamboo pipe directly on to the unglazed surface of the porcelain, presumably there was some sort of temporary adhesive to keep the powder from blowing away. The end of the bamboo pipe had gauze tied to it to defuse the pigment. The areas to be left without the powder-blue could be protected by wax-resist, rather like batik textiles. These plain areas could ether be left undecorated (see `Sold Items` 19206 and 17133) or painted afterwards (21438 and 21439) thus adding further variations to this technique. The powder-blue pieces of the late Ming appear to all be small objects for the Japanese market, the distribution of the blue appears patchy and uneven, possibly as this appealed to Japanese tastes, rather than because of any technical short comings. The effect of the powdered cobalt is altered during the firing process, because it was added prior to glazing, the cobalt particles rise and spread slightly within the glaze itself giving a soft, almost out of focus effect. Powder-blue porcelain was at its most fashionable during the Kangxi period, the blue was of a more brilliant tone and the appearance was altogether more even and refined than the Ming examples because it had to look `smart` and luxurious for the grand European houses it was destined for. The whole piece could be covered in a powder-blue ground and then decorated with gilding (see `Sold Items` 17684) or areas could be reserved and then decorated with Famille Verte enamels (20471) or painting in cobalt blue, or even decorated with blue, celadon and copper red. The objects produced during the Kangxi period varied greatly in size and included everything from teabowls to massive vases, the areas left in reserve were often much larger than their Ming counterparts, so wax-resist was replaced by the use of paper to mask the areas to be protected from the powder-blue. This technique was used to a much lesser extent during the Yongzheng (1723-1735) and Qianlong (1736-1795) periods, however there was a large revival during the latter part of the 19th century, most of these designs harked back to the Kangxi period.
This Kangxi blue and white porcelain jar and cover is illustrated in : Renaissance and Baroque, Silver, Mounted Porcelain and Ruby Glass from the Zilkha Collection (Timothy Schroder, Paul Holberton Publishing, 2012. ISBN 978-1-907372-35-3) page 272, fig. 90.