Technological investigation of luster decorated ancient majolicas

In this work some luster decorated ancient ceramics have been analyzed in order to acquire knowledge about technological procedures in luster production during the Renaissance period in Italy. Luster is a thin decorative metallic film present on the surfaces of some previously glazed ancient majolicas. It was obtained by applying on the majolica surface a mixture containing silver and copper compounds. Subsequently the object was fired in a reducing atmosphere. It was found that the luster color, red-like or gold-like, depends not only on the chemical composition, determined by Inductively Coupled Plasma Emission Spectroscopy (ICP-OES), but on the dimensions of silver and copper metallic nanoparticles forming the luster too. Nanocrystals' dimensions and structural characteristics were determined by Transmission Electron Microscopy (TEM). As obtaining a satisfactory luster depends on the composition of the underlying glaze too, the chemical composition of the glazes have been determined and the analytical data were submitted to statistical multivariate analysis.