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The potentialities of nanomaterials for application in the field of conservation have been widely investigated in the last two decades. Among nanomaterials, nanolimes, i.e., dispersions of lime nanoparticles in alcohols are promising consolidating products for calcareous materials. Nanolimes are effective in recovering the very superficial loss of cohesion of decayed materials, but they do not always provide sufficient mass consolidation. This limitation is mainly related to the deposition of the nanoparticles nearby the surface of the material. Experimental research has been set up with the aim of improving the in-depth deposition of lime nanoparticles. Previous research by the authors has shown that nanolime deposition within a substrate can be controlled by adapting the nanolimes properties (kinetic stability and evaporation rate) to the moisture transport behavior of the substrate. Nanolime properties can be modified by the use of different solvents. In this research, nanolime dispersions have been further optimized for application on Maastricht limestone, a coarse porous limestone. Firstly, nanolimes were synthesized and dispersed in ethanol and/or water, both pure and mixed in different percentages. Subsequently, based on the kinetic stability of the nanolime dispersions, the most promising solvent mixtures were selected and applied on the limestone. The deposition of lime nanoparticles within the limestone was studied by phenolphthalein test, optical microscopy and scanning electron microscopy. The results confirm that nanolime dispersed in a mixture of ethanol (95 %) and water (5 %) can guarantee a better nanoparticles in-depth deposition within coarse porous substrates, when compared to dispersions in pure ethanol.

The conservation and durability of historical renders must be carried out through compatible techniques and materials. An important operation is the restitution of historical renders cohesion, turned friable by the loss of binder, usually due to physical and/or chemical actions. Surface consolidation is based on the use of materials with aggregating properties. This operation is reached usually through the application of organic or mineral consolidants, but inorganic consolidants are becoming preferred due to better compatibility and durability. In this article two mineral compatible consolidation products were studied: a commercial suspension of calcium hydroxide nanoparticles in propanol and a limewater dispersion of ethyl silicate. Microscopy (optical and scanning electron microscopy) and X-ray microanalyses of the consolidation products and of the consolidated mortar specimens were carried out. To assess the mechanical properties and product's efficacy, analyses of the compression, flexural strength, and superficial hardness were performed. Microscopy results show that limewater dispersion of ethyl silicate forms platelike silica gels, which can interfere in product penetration. Otherwise, nanolime particles permit homogeneous distribution and optimum penetration on the treated substrate, improving cementing action and the agglomeration process.