A comparative study on the color change of pigments due to the consolidation of conventional spectroscopic techniques and laser-induced breakdown spectroscopy

The present study seeks to investigate the changes in the elemental composition of pigments due to consolidation. Therefore, the effect of the consolidation of hydroxypropyl cellulose (Klucel G) of different concentrations and its mixture with zinc oxide (ZnO) nanoparticles on the black, red, and ochre pigments applied on chalk-based preparation layers before and after aging were studied. Additionally, the role of ZnO nanoparticles in protecting the pigments after UV aging has been examined. The color change due to consolidation solutions was measured by the spectrophotometer, scanning electron microscopy with energy dispersive X-ray (SEM–EDX), and laser-induced breakdown spectroscopy (LIBS). Interestingly, the results revealed that all the painted samples treated with Klucel G (1%) and nano-ZnO (1%), as additives, showed the least color change values. Moreover, SEM–EDX and LIBS analyses prove the ability of ZnO nanoparticles to enhance the durability of consolidants and coatings toward aging.