A multi-analytical approach for the conservation of the Brera Napoleon by Antonio Canova

This paper reports some results of the conservation project carried out on the bronze statue of Napoleon Bonaparte by Antonio Canova, cast in the XIXth century and located outdoors in the main courtyard of the Brera Gallery in Milan. A preliminary diagnostic campaign allowed to characterize the alteration patinas through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS) measurements, putting in evidence the ubiquitous presence of brochantite Cu4(SO4)(OH)6 and, in sheltered areas, antlerite Cu3SO4(OH)4. Residues of an acrylic polymer (Incralac) and of waxes applied in previous conservation interventions were also found, as well as proteins. In addition, the corrosion rate of the surfaces was evaluated through on field Electrochemical Impedance Spectroscopy (EIS) measurements. On the basis of these results, cleaning procedures including the laser ablation were carried out and monitored with EIS and portable FTIR spectroscopy.