Traced a preliminary historical annotation, the essay presents the analytical activities that supported the elab- oration of the restoration project of the baroque façade of Palazzo Bertini in Ragusa (included into the Unesco World Heritage List) and the phases of the restoration site regarding the techniques of cleaning, consolidation and reintegration of the stone surfaces and ancient plasters of the historical architecture.The building was erected in the late eighteenth century along one of the main axes of the urban system developed after the earthquake of 1693 in eastern Sicily. The original balance of the Baroque façade, however, was modified in 1847, when a significant overhaul of the road conformation was carried out, with the lowering of the original level. The main portal was lengthened and the three secondary portals became the openings with a balcony placed at the intermediate level; they are characterized by the three stone-pitched masks placed in the arch-wrench, which represent a “mendicant”, a “nobleman” and an “eastern man”.The restoration has been directed towards the most rigorous conservation of all the elements of the articulated Baroque façade. The cleaning operations provided for the removal of degradation phenomena respecting the material surfaces and natural patinas. The architectural elements of calcarenite and the masks of stone-pitch (a stone of asphaltic nature) had developed extensive and serious phenomena of disintegration and formation of black crusts; they have been consolidated - depending on the case - with the use of ethyl silicate or the applications of stable solutions based on micronized hydraulic lime, and, afterwards, cleaned with the nebulized water or the chemical packs with ammonium carbonate; the biological patinas have been removed with biocidal products. The preliminary thermographic investigation of the eighteenth-century plaster emphasized the phenomena of detachment from the wall support and scientifically guided the consolidation with the micro-injections of hydraulic lime and the reintegration of the lacunas. Some extraneous elements have been removed, such as the pins of old electric cables and some improper cement mendings. The reintegration of the gaps in the plastered surfaces has been carried out with attention to the chemical-physical compatibility with the existing mortars, verified through the laboratory tests on sample and thin slice of stone and plaster, which have highlighted their mineralogical- petrographic characteristics. The intervention on the valuable elements in wrought iron has been carried out by the removal with brushes of the oxidative layer and other accumulation substances; the subsequent treatment involved protection with microcrystalline wax passed by brush.Some computer simulations guided the final operation of “color veiling” (calcium carbonate water) in some areas of the Baroque façade. The article describes the interventions carried out during the restoration site and their outcome, recalling the reflections that led to the operational choices. A closing reflection wants to underline the importance of conservation of historical plasters and suggests avoiding the extensive repainting of the facades with colors of pure invention, which alter the perception of the urban scene in the historical districts.
|Numero di pagine||12|
|Stato di pubblicazione||Published - 2018|