Innovative treatments for the protection of outdoor bronze monuments

We present here the results so far achieved in the framework of the European Union ARTECH project, concerning the evaluation of innovative treatments used to preserve outdoor bronze. Traditional coatings, such as Incralac and/or synthetic waxes (R21, TeCe Wachs 3534F), were compared with different organo-silanes materials. In order to evaluate their effectiveness, applications were made on urban natural aged copper plates and also on parts of a work of art: the sceptre of the equestrian bronze statue of Bartolomeo Colleoni, in Venice. Electrochemical impedance spectroscopy (EIS), attenuated total reflectance (ATR) mapping, Fourier transform infrared (FTIR) microscopy and colorimetric measurements were performed after an 8-months exposure. The results clearly demonstrate how the corrosion resistance of some of the new tested treatments has the same order of magnitude of those commonly used at present, with the great advantage of having no modification in the colour appearance of the treated patina.