Ancient stone artifacts and architecture deteriorate over time due to environmental factors such as air pollution, salt efflorescence, and biodeterioration. As a result, effective stone consolidants are necessary for the conservation and protection of stone materials, specifically calcareous stones. Alkoxysilanes are effective stone consolidants, undergoing hydrolysis and condensation to produce a sol-gel capable of penetrating the stones internal porous structure. However, demands for improvements in commercial formulations have led to research efforts focused on increasing flexibility, “breathability” and durability. In order to allow water vapor evaporation out of the stones internal pores post-consolidation, a “breathable” component within the formulation is required to permit the transport of water molecules. Polyhedral oligomeric silsesquioxane (POSS) structurally contains a nano-meter sized cage, allowing for water permeability in addition to mechanical integrity. Polydimethylsiloxane (PDMS) was utilized for increasing flexibility and hydrophobicity. Consolidant formulations incorporating both POSS, PDMS, and additional compounds were sprayed on Indiana Limestone and Royal Danby Marble. The experimental formulations were optimized using Design Expert and analyzed by weight loss profile, percent solids, contact angle, film appearance, mechanical testing and accelerated weathering.

Alkoxysilane sol-gel consolidants for calcareous stone

256th National Meeting (2018)

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