Durability of a sunlight-curable organic–inorganic hybrid protective coating for porous stones in natural and artificial weathering conditions

• The durability of an experimental sunlight-curable O-I hybrid coating was assessed.
• Excellent resistances to salt crystallization were proved.
• Optimal resistance to in humid and polluted atmosphere were obtained.

Several weathering aging tests were performed for assessing the durability of an innovative sunlight photopolymerizable nanostructured organic-inorganic (O-I) hybrid coating, namely HYBRIDSUN. The latter was applied on a calcarenitic porous stone typical of Apulia Region, Italy (Lecce Stone, i.e. LS) and photo-cured by means solar radiations up to 55 h. The protective performances of the stone specimens treated with HYBRIDSUN, when exposed to both realistic and accelerated weathering conditions, were studied by performing natural and artificial aging tests, such as resistance to abrasion, salt crystallization, freeze-thaw and SO2 in moist environment. The effects of the natural and artificial weathering aging on hydrophobicity and color change of treated stones were, finally, monitored, upon to two exposure years to outdoor conditions, confirming the outstanding properties of the experimental product to protect the stone surface from all the environmental agents investigated.

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