Removal of simulated dust from acrylic paints by laser irradiation at IR, Vis and UV wavelengths

This study aims to investigate whether laser cleaning may be a valuable method for the removal of soiling from water-based acryclic emulsion paints in comparison to traditional cleaning methods. Acrylic-grounded canvas was painted with three different paints (yellow ochre, titanium white and red alizarin) in a poly-butyl-acrylate and methyl methacrylate binder. An acrylic binder was used as a reference. The samples were covered with carbon, SiO2 and soot. Cleaning process ablation rate studies were carried out with a Q-switched Nd:YAG laser at 1064, 532 and 355 nm and a KrF Excimer laser at 248nm. The energy densities varied from 0.03 to 0.69 Jcm-2. The irradiated tests at 248nm were monitored by LIBS analysis. On the samples irradiated at 1064nm, various analytical methods were carried out. A determined alteration of the titanium white paint resulted in a marked decrease in the glass transition temperature (Tg). Furthermore, discoloration (yellowing) occurred on the binder and titanium white paint. The ochre darkened slightly but the alizarin was unchanged. When compared with the samples cleaned with water-based solvents, the samples cleaned with laser appeared cleaner. However, SEM/EDX and ATR showed that SiO2 was still present on the surface after laser cleaning at the tested conditions.