Condition Survey on XIV–XVIII Century Funerary Monuments in the Cloisters of St. Anthony Basilica in Padua

Most of the funerary monuments in the cloisters of St. Anthony’s Basilica, being located in the centre of Padua, have suffered of marked decay processes related to the recent industrialisation which has strongly increased sulphur based-compound in the atmosphere. Extensive sampling of the monuments were performed following the European guidelines of CEN TC 346. Surface samples were collected from those areas which showed severe symptoms of stone deterioration. Care was taken to ensure that the samples were representative of each monument. Petrographic analyses of all surface crusts showed gypsum, in both microcrystalline flakes and in acicular crystals. Gypsum is the predominant phase due to sulphation processes, according to the interactions of the atmosphere in contact with the stone surface. SEM analyses (BSE images) of cross sections showed extensive micro-cracks in the limestone, parallel to the stone/crust interface, completely filled with gypsum. The study of the decay products, their extent on the surface and in depth of the stone and the causes that have led to their formation have allowed an important evaluation of decay degree and consequently the most appropriate procedure of restoration to be carried out.