EDXRF analysis of blue pigments used in Valencian ceramics from the 14th century to modern times

EDXRF analyses of cobalt-blue pigments were performed on 73 pieces of Valencian ceramics from the beginning of the 14th century up to the 20th century. In 67 of such samples, the pigment decoration was applied together with a tin opacified lead glaze cover on the clay body. In five samples the pigment was applied on the clay body without a glaze cover. The comparison between EDXRF spectra from coloured and non-coloured areas contains information about the pigment composition. Elements like Mn, Fe, Co, Ni, Cu, Zn and As are identified as characteristic of blue pigments; different associations of these elements were found and correlated with the chronology of the samples. The results can be used for identifying the different types of cobalt ores employed in the manufacture of blue pigments and their provenance.