Lustre pottery decorations of Renaissance majolica are mainly characterised by Cu and Ag nanoparticles dispersed in the glassy network of the glaze. Following this finding, a study has been carried out on several gold and red original lustre samples, with the objective to better understand the lustre formation mechanism and manufacturing. Preliminary measurements were carried out by XRF, SEM, TEM, Vis-NIR; then EXAFS measurements were carried out at the BM8 beamline GILDA of ESRF. While XRF and SEM-EDS measurements indicated that gold and red lustre decorations are characterised by the presence of Ag and Cu, surface plasmon resonances in Vis absorption spectra clearly indicated that mainly responsible of the colour for gold and red lustre are Ag and Cu metal nanoparticles respectively. These results have been confirmed by EXAFS measurements. However, in most cases, Cu and Ag have been also found in oxidised forms (Cu⁺ and Cu²⁺, with a large prevalence of Cu⁺). The simultaneous presence of metallic and ionised Cu and Ag is coherent with a lustre formation mechanism where the first step consists of an ion-exchange between Cu and Ag ions from the oxides and salts used according to the original lustre recipe, and the alkali ions in the glaze (on average, total Na⁺ and K⁺: 5-15% wt). The fractions of reduced Ag and Cu are mainly responsible of the colour. These fractions can be low and variable case by case, depending on used recipes, reductive conditions and temperature of the kiln. It has been found that even the metallic Ag/Cu ratio cannot be simply and univocally correlated with the colour. Further information has been recently obtained through the transnational access services offered by the Eu-ARTECH project within the 6^th F.P. of the EU (http://www.eu-artech.org). In particular, through the MOLAB facility, XRF, micro-Raman, AFM, and UV-Vis measurements have been carried out on original plates of the Renaissance at the V&A Museum.

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