Co-solvents and chelating agents confined in complex fluids for the cleaning of surfaces of works of art

In a modern society that is always more and more sensitive to the respect and the preservation of the environment and its living beings, and where the research of sustainable resources and ecological solutions is continuous, also in the field of the Cultural Heritage conservation, in the last decades, the developing of innovative technologies has been inspired by those principles. It’s in this context that in the laboratories of the chemistry department of the University of Florence and CSGI Consortium, a new family of Highly Viscous Polymeric Dispersions (HVPDs) for the cleaning of artistic, fragile surfaces was formulated and studied. They are 95% aqueous systems obtained from poly(vinyl alcohol) (PVA) or poly(vinyl acetate)s (PVAc) via complexation and crosslinking between the side-chain hydroxyl groups of the polymer and borate ions. Due to the low toxicity of the formulations these HVPDs are very attractive eco-friendly cleaning tools for the conservation of painted surfaces. They can incorporate a wide range of organic liquids, with particular reference to the less toxic ones, and thank to their high viscosity and thickness, the significant retention of the solvent reduces the potential damages to the original materials of the work of art but also the intoxication risk for the operators and the environmental impact. Their cleaning action is effective, confined to the desired area, controllable and gradual, parameters that are greatly appreciated by restorers. Their viscoelastic properties ensure a good adhesion onto the surface (even the molded, irregular or vertical ones) and easiness of removal in one piece through lifting with tweezers; thereby, the potential for residues is minimized and the clearance step with neat solvents often is not necessary.