Removal of Simulated Dust from Water-Based Acrylic Emulsion Paints by Laser Irradiation at IR, VIS and UV Wavelengths

Abstract

This study aims to investigate whether laser cleaning may be a valuable method for the removal of soiling from water-based acrylic emulsion paints in comparison to traditional cleaning methods. Acrylic-grounded canvas was painted with three different paints (yellow ocher, titanium white, and red alizarin) in a polybutyl-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 1,064, 532, and 355 nm and a KrF Excimer laser at 248 nm. The energy densities varied from 0.03 to 0.69 J cm-2. The irradiated tests at 248 nm were monitored by laser-induced breakdown spectrometry (LIBS) analysis. On the samples irradiated at 1,064 nm, 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 the titanium white paint. The ocher 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, scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDX) and attenuated total reflectance (ATR) showed that SiO2 was still present on the surface after laser cleaning at the tested conditions.