Comparative Study of Ethyl Silicate and Nanolimes with Fluorescent Properties as Consolidants for Mural Paintings and Mortars

The consolidation of mural paintings presents a significant challenge for conservators, as the treatments applied must not only be effective but also preserve the aesthetic qualities of the artwork. Ongoing research focuses on developing new products that are more efficient, durable, and compatible with the physicochemical and aesthetic characteristics of the original materials, thereby addressing the limitations of existing consolidants. This study examines two consolidants for mural painting restoration: Estel 1200® (C.T.S., Madrid, Spain), a commercially available and widely used ethyl silicate-based product, and Nanorepair UV® (Patent: ES-2766074-B2, Pablo de Olavide University, Seville, Spain), a nanocomposite composed of calcium hydroxide nanoparticles doped with zinc quantum dots. On mortar specimens, prepared according to the Roman fresco technique, the application method for the proposed treatments was optimized. The applicability of the treatments for mural painting conservation was studied by colorimetric measurements and SEM imaging to detect and characterize the formation of surface layers. The effectiveness of the treatments was quantitatively evaluated with tape-peeling cycles. The results show that, although both treatments enhance the consolidation state of mural paintings, Nanorepair UV® proved to be a more effective consolidant, without altering the aesthetic or physicochemical properties of the artwork. Additionally, this treatment allows for straightforward evaluation of its penetration and enables distinction between treated and untreated areas through the fluorescence of the zinc oxide quantum dots.