Electrochemical Characterization of Egyptian Blue Pigment in Wall Paintings Using the Voltammetry of Microparticles Methodology.

The solid state voltammetric response of Egypt blue, Han blue and ploss blue pigments upon attachment to graphite electrodes in contact with aqueous phosphate buffer at pH 7.0 is studied by voltammetry of microparticles and scanning electrochemical microscopy. Such voltammetric responses, combined with those for synthetic specimens consisting of binary mixtures of the pigment and SiO₂ or CaCO₃ as well as ternary ones of CaCO₃ and SiO₂ mixtures allow for the identification of the pigment and the support in samples from wall paintings using different electrochemical parameters, in particular upon performing the Tafel and modified Tafel analysis of voltammetric peaks. Identification of Egypt blue in microsamples of murals from a Roman archaeological site in Castulo (Jaén, Spain) is discussed. [ABSTRACT FROM AUTHOR]