Effectiveness of some protective and self-cleaning treatments: a challenge for the conservation of temple G stone in Selinunte

The Temple G of the Archaeological Park of Selinunte (Italy), the largest in Europe, is one of the most impressive temples in the Magna Grecia. Today, it is completely destroyed due to a strong earthquake occurred in the Middle Ages. The used stone is a calcarenite coming from the ancient and renowned quarries of Cusa near the acropolis. This work comes from the today's proposal of Temple G anastylosis. The goal of the work is to provide the results relating the protective effectiveness of three polymer formulations, appropriately selected, on stone samples taken from the “Capitello” quarry, part of “Cusa quarries”. The formulations functionality was deployed by adding TiO2 nanoparticles to provide a self-cleaning property that was evaluated by methylene blue photo-degradation test. Water absorption by capillarity and water vapour permeability tests as well as colorimetric measurements, were performed according with UNI EN regulations to evaluate the performances of the protective treatments, also in presence of TiO2 nanoparticles. The effect of TiO2 nanoparticles on the polymer stability was investigated by Infrared Spectroscopy. The study highlighted the pros and consof the changes caused by the protective agents on the stone surface providing useful information for a conscious choice of products to be used for an efficacious conservation treatment of Cusa stone.