This type of brush washer is described as of 'gong' shape or tangluo xi, as it has a very compressed body.
This washer belongs to an exclusive group of eight vessel shapes that are covered in this extremely desirable peachbloom glaze. Known as the ba da ma or 'Eight Great Numbers', the sets were especially devised in these classic forms to serve as requisite appointments for the Emperor's writing table. Complete sets are extremely rare, with one in the Metropolitan Museum of Art, New York, illustrated by S. Valenstein, The Handbook of Chinese Ceramics, New York, 1989, rev. ed., p. 237; and another from the Jingguantang Collection, sold in our Hong Kong rooms, 3 November 1996, lot 557 and now in the Baur Collection, Geneva.
Similar brush washers have been widely published and are in numerous public and private collections. John Ayers in the transcript of his lecture, "The 'Peachbloom' Wares of the Kangxi period (1662-1722)", TOCS, vol. 64, 1999-2000, pp. 31-50, provides a thorough discussion of peachbloom wares, as well as wares of similar shape with pale celadon and pale blue glazes. He notes that Stephen Bushell in Oriental Ceramic Art, new edition, London, 1981, describes various shades of the peachbloom glaze, one of which is jiangdou hong (bean red), "in an allusion to the small Chinese kidney bean, with its variegated pink colour and brown spots". He goes on to suggest, p. 49, that these wares, rather than having been made exclusively for the use of the Kangxi emperor, may have been presented as gifts to members of the court on important court occasions.
Whatever the case may be, these wares have always been and continue to be highly prized.