Cleaning of Wall Paintings and Stones

Abstract

The surface of artifacts interacts with the environment, leading to aging and degradation. Soiling is one of the main factors that contribute to the alteration of artistic and historical surfaces, and is often associated with both chemical and mechanical degradation. The effects of these processes on porous inorganic substrates such as wall paintings and stone are usually strongly enhanced if organic coatings (e.g. acrylic and vinyl-based polymers), applied in previous restoration treatments, are present. In fact coatings alter the physico-chemical properties of the artifacts (e.g. water vapor permeability), enhancing the degradation processes promoted by salts and pollution agents, ultimately the detachment and loss of the painted layer. In the recent years innovative formulations based on nanostructured fluids have been developed and successfully used for the removal of both grime/dirt and detrimental synthetic or natural coatings. This chapter focuses on the formulation and application of surfactant-based complex fluids, such as microemulsions and micellar solutions, for the removal of dirt and coatings from the surface of monuments and wall-paintings. Due to the low content of organic solvents, these systems have a very low eco-toxicological impact as compared to pure solvents or solvent blends; moreover, the nanostructure of the cleaning fluids grants the effective and selective removal of undesired layers.

Hydrophobic and Photocatalytic Treatment for the Conservation of Painted Lecce stone in Outdoor Conditions: A New Cleaning Approach

“…Several cleaning procedures (chemical, mechanical, laser, and biological methods) have been proposed [10,[33][34][35][36][37]. Among these, chemical and mechanical methods are the most used by restorers.…”

Advanced methodologies for the cleaning of works of art

“…These coatings are typically yellow and crack upon aging, producing strong aesthetical alterations on artistic surfaces [54,[58][59][60][61]. In addition, they can produce extensive damage on stone and wall paintings, where the coatings fill and block the substrate porosity; this enhances the pressure induced in the pores by salts contaminants (usually present in these artifacts) as the salt crystals form in narrowed and constrained spaces at the coating-substrate interface [62].…”

“…Extensive assessment and validation by end-users worldwide eventually culminated in the market uptake of these cleaning fluids as new benchmarks in art cleaning tools [62].…”

“…For the main references to the use of these solvents in cleaning formulations see refs. [34,46,47,54,57,62,78,79,114,144]. traditional solvent blends, taking advantage of non-classical cleaning mechanisms that work on dewetting or swelling/ detachment processes.…”

Materials and Technologies for the Consolidation of Historic Plasters by the Wetting and Surface Penetration Method

“…The use of nanomaterials with particle sizes of up to 1µm, whose properties are somewhere at the intersection between the properties at the level of molecules and matter [10,11], is the subject of extensive scientific research due to their positive physical and mechanical properties such as high chemical performance, excellent plastic, consolidation and diffusion properties, cleaning capabilities and more. The tested nanomaterials mainly include nanodispersions based on hydroxides, carbonates, or sulphates [12,13,14].…”