The MEDUSA Project: MarinE outDoor bronze sUrfaceS: a methodological Approach

The MEDUSA project aims to assess a methodological approach for making the protection of bronze monuments in marine/coastal environments increasingly long-lasting and responsive to specific environmental conditions and climate variations by environmentally sustainable solutions. Bronze foundry mock-ups were analysed before and after patination by two largely used ‘Verde Messina’ and ‘Liver of sulfur’ patinas. Protective coatings based on a microcrystalline wax used in outdoor bronze conservation were considered. A nanostructured coating was designed by selecting beta-cyclodextrins (β-CD) as nanocarriers for the conventional 1-H Benzotriazole (BTA) corrosion inhibitor. The reference coating obtained by adding BTA directly to wax (TR) and the nanostructured coating (T1) were brushed on mock-ups by a professional restorer. The surface properties of bronze mock-ups were investigated by several portable and laboratory Non-destructive Techniques NdT adopting a well-defined measurement grid to check the variability of surface properties before treatment (S0), upon protective coating application (S1) and after natural weathering (S2) in marine industrial and rural exposure sites. Preliminary results of the MEDUSA project obtained by digital optical microscopy, colorimetry, thickness and roughness measurements, Electrochemical Impedance spectroscopy, µATR-FTIR, µRaman and VNIR Hyperspectral Imaging are presented. Multivariate data analysis was used to investigate the homogeneity of the patina surface properties of both groups of mock-ups, and to identify sub-groups with similar physical properties to be used for treatment test comparison.