Cobalt Blue in Medieval Ceramic Production in the Valencian Workshops: Manises, Paterna and Valencia (Spain).

The first documentary mention of cobalt use in the medieval kingdom of Valencia dates as far back as 1333. Before that, there is no evidence for the use of safra or cobalt pigment. The first cobalt was used in production of lustre-ware, proving the improvements in the manufacture of wares with tin-glaze earthenware decoration during the first half of the fourteenth century. X Ray fluorescence analysis suggests a variation in the detected spectrum of blue pigment through the years, this fact when considered with shape, draw and decorative evolution allows us to propose a very close dating for some decorative groups produced in Manises and Paterna and that is the main target of this paper.