Femtosecond pulse laser cleaning of spray paint from heritage stone surfaces

We explore the use of femtosecond laser pulses to clean a variety of colors of spray paint from the Moruya granite, a stone with high heritage value that is widely used for monuments and sculptures in Sydney and New South Wales (Australia). The efficiency of the cleaning treatment and the effects on the stone substrate are evaluated using optical microscopy, optical profilometry, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and colorimetry. We demonstrate that femtosecond laser cleans granite without damaging it and without discoloration when the laser fluence is set below the damage threshold of the stone. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

In this study, we investigate the use of femtosecond laser pulses to remove various colors of spray paint from Moruya granite. The efficiency of the cleaning treatment and its effects on the stone substrate are evaluated using multiple analysis methods. The results demonstrate that femtosecond laser can successfully clean granite without causing damage or discoloration when the laser fluence is below the stone's damage threshold.