The byzantine fresco of Dormitio Virginis (12th century): diagnosis and conservation by means of innovative materials

Byzantine monks, who settled in eastern Sicily after the conquest of Emperor Justinian, brought on the island figurative languages and architecture that influenced all the artistic future. An extraordinary example of Byzantine culture in Sicily is described by a beautiful pictorial artwork (12th century), inside the monastery of Santa Maria del Rogato in Alcara Li Fusi (Messina), representing the only fresco in Sicily of the "Dormitio Virginis". The technical peculiarity that characterizes the fresco painting, together with its severe decay conditions (related to a cohesion loss of the preparatory layer and of the painting itself), make this artwork an exceptional case of study, finalized to the knowledge of the original materials and to project accurate intervention actions of restoration. Samples have been investigated by optical and SEM-EDS microscopy, X-ray powder diffraction, X-ray fluorescence, in order to throw light, on the painting technique, the original constituent materials (pigments and binders) and their state of conservation. Afterwards, taking into account the problems relative to conservation and the technical peculiarities observed in the artwork, the research has been carried out to find suitable consolidant materials, for a sustainable protection intervention. In fact, consolidation and conservation of historic mortars and frescoes require materials, which are compatible with the components originally used. The application of nanolime offers such possibility, especially for frescoes restoration [1]. In the present work, a pure and notcommercial nanolime was employed, produced by a new and innovative method of synthesis, recently patented [2]. The nanolime suspension, dispersed in alcohols, thanks to the reduced particles size, was perfectly compatible, stable, penetrating and extremely reactive in air, avoiding whitening of the treated surfaces and leading to a complete conversion into CaCO3, by simple reaction with atmospheric carbon dioxide [3]. Consolidation of mortar by a combined treatment of nanolime with esters of silicic acid were evaluated too. The calcium carbonate nanoparticles formed after the nanolime treatment catalyze the gel formation resulting in improved mechanical properties [4]. Finally, tests to evaluate the efficacy of treatments in terms of water absorption and re-cohesion of original materials were carried out, together with a comparison with consolidants already used in conservation interventions.