ABSTRACT
The stone surfaces of the inner east side of Cemetery of Pisa are affected by extensive deterioration phenomena connected with the lithotype and the environmental condition. Past consolidating and protective treatments have improved the flaking and powdering of the stone, which made impossible to use traditional cleaning methods. For the gradual removal of soil and altered film, the single or combined action of two mid-infrared lasers operating at different wavelength were tested: Nd:YAG laser (1064 nm, 6 ns) and Er:YAG laser (2940 nm, 150 µs, 250 µs, 400 µs). The optimal cleaning parameters have been settled up varying the fluence, pulse duration, and wetting conditions for each typology of material to be removed. Test evaluations have been carried out by comparing the marble surface before and after the laser treatment with different analytical techniques. The optimized laser cleaning methodology has been successfully applied for the complete and safe cleaning of the pillar and its carved capital.
