Rimozione controllata di ridipinture a olio da dipinti su tela del XX secolo mediante ablazione con laser Nd:YAG (1064 nm) LQS

The removal of unwanted overpaintings from 20th century modern paintings represents a very difficult challenge, which usually implies the choice of inefficient treatments, as the use of polar solvents and/or a moderate mechanical actions. The cleaning attempt by traditional methods might be more complicated whether the layer to be removed is much more thicker (more than 50 ?m) than the layer underneath and if they were both applied using a lipidbased binder. In such framework, the study is aimed at exploring for the first time the potential of Long Q-Switching Nd:YAG (1064 nm) laser for selective ablation of oil overpaints. Material and laser treatments characterizations were performed by using ESEM-EDX analysis, stratigraphic examinations, portable Raman and Fourier transform infrared (FTIR) spectroscopies. According to the stratigraphy and material composition of the painting to be restored, representative mock-ups were prepared in order to determine the ablation thresholds and optical properties. The parameterization achieved on the mock-ups allowed interpreting and maximizing the selectivity of the laser conservation treatment carried out on the real case.