Diagnostic campaign and innovative conservation treatments carried out on the statue "La Speranza" by Odoardo Fantacchiotti

This work is focused on the conservation-restoration workscarried out on the Speranza, monumental sculpture of the 19th century placed inside the English Cemetery in Florence. The statue was covered by scattered greenish and black-grayish patinas mainly due to the biological growth. Optical microscopy, culture-based methods and CF-PAM imaging (Pulse Amplitude Modulated fluorometry of the Chlorophyll Fluorescence) were used to characterize the biodeteriogens, while the study of the stone material and of the decay layers was performed trough microstratigraphic observations and X-ray diffraction analyses. Laser cleaning trials were carried out using different wavelengths (1064 nm and 532 nm) and pulse durations. The optimization of the laser parameters was performed taking into account the results obtained from the stratigraphic layers observations of the thin cross-sections of the stone material and real time CF-PAM imaging of the phototrophic presence.The study allowed improving, planning and accomplishing of the laser cleaning treatment of the whole statue.