PIXE ANALYSIS OF ARTISTIC BLUE GLAZES AND THE USE OF COBALT PIGMENTS IN CERAMICS DURING THE ITALIAN RENAISSANCE

摘要

PIXE has been used to extract the elemental composition of cobalt blue glazes in 55 dated and undated terracotta sculptures from the Florentine della Robbia school. The data, consistently with previous work, show a rapid change in the composition of blue glazes and locate it just before 1520. The change is marked essentially by the presence of arsenic and bismuth in the glaze and by reduced amounts of iron and nickel after 1520. We speculate that this is due to procedures introduced to industrialise the blue pigments production more than to exploitation of different families of cobalt minerals. We observe in this unique ensemble more variability of products than was known before.