Nowadays one the main problem of stone monuments conservation is not only the natural environment deterioration but
the defaced, in particular esthetic, due to graffiti. This paper presents the different stages of the cleaning graffiti
research: the laboratory study phase, in which the aims were to investigate the laser cleaning effect on substrate and
testing user-friendly and efficient solutions for in situ application; the application phase in which the study results were
applied in the restoration of Palazzo de Mattis facade. The graffiti cleaning were carried out by using a Q-Switch
Nd:YAG laser source (λ=1064 nm with pulse duration, t=8 ns, f=2 to 20 Hz, energy per impulse up to 280 mJ) in dry,
wet and Very wet modes adopting the Daurelio technique n.1 (blade spot laser). The Q-Switch Nd:Yag laser source
has demonstrated to be the most suitable for a fully or, according to new restoring theory, "de veiling" graffiti ablation.