Nanomaterials for the Consolidation of Stone Artifacts

Stone artifacts constitute a large part of the global cultural heritage, and their preservation is thus central in order to bestow such patrimony upon future generations. Stone is constantly exposed to both physical and chemical degradation caused by a variety of factors (environmental, anthropogenic, biological, etc.), and as a result the mechanical properties of stone can be severely weakened. Powdering of surfaces, detachment and flaking, all are commonly observed on monuments, statues and other works of art, requiring effective methods to consolidate the weakened layers. In the last decades, colloid and material science have been providing effective solutions that allow the strengthening of stone layers, while respecting the original physico-chemical properties of the treated artifacts. This chapter reviews the main achievements in the field of nanomaterials applied to stone consolidation, discussing the principles that underpin the materials development and application to artifacts. Consolidation systems comprise both inorganic (e.g. dispersions of alkaline earth hydroxide nanoparticles) and hybrid nanomaterials (e.g. organic-inorganic silica gels), to account for the preservation of carbonate and sandstone.