What is "zaffre"

Zaffer \Zaf"fer\, n. [F. zafre, safre; cf. Sp. zafra, safra, It. saffera, G. zaffer; all probably of Arabic origin. Cf. Zaphara.] A pigment obtained, usually by roasting cobalt glance with sand or quartz, as a dark earthy powder. It consists of crude cobalt oxide, or of an impure cobalt arseniate. It is used in porcelain painting, and in enameling pottery, to produce a blue color, and is often confounded with smalt, from which, however, it is distinct, as it contains no potash. The name is often loosely applied to mixtures of zaffer proper with silica, or oxides of iron, manganese, etc. [Written also zaffre, and formerly zaffree, zaffar, zaffir.]

n. 1 a blue pigment obtained by roasting cobalt ore 2 a cobalt blue colour, like that of the pigment

Zaffre, a pre-scientific substance (see List of alchemical substances), is a deep blue pigment obtained by roasting cobalt ore, and is made of either an impure form of cobalt oxide or impure cobalt arseniate. During the Victorian Era, zaffre was used to prepare smalt and to stain glass blue.

The first recorded use of zaffre as a color name in English was sometime in the 1550s (exact year uncertain).