Definitions of zaffre

  1. Impure oxide of cobalt: the residuum of cobalt, after the sulphur, arsenic, and other volatile matters have been expelled by calcination. So that it is a gray or dark-gray oxide of cobalt, mixed with a portion of silica. When fused into a glass it is intensely blue, and is much used by enamellers and porcelain manufacturers as a blue color. The american dictionary of the english language. By Daniel Lyons. Published 1899.
  2. The impure oxide of cobalt, which, melted with silica and potash, and reduced to powder, becomes the powder-blue of commerce. Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.