Knowledge and strategies for conservation of historic technologies

The buildings of the pre-modern small historic centres are characterized by the use of materials deriving from nearby surrounding open areas, in great harmony with the natural material of the external place. In relationship to the soil materials, the appearance of the different urban buildings changes. For instance, in Sicily, the region analyzed in this paper, whereas most of the historic built environment is carried out in local porous limestone (calcarenite), in some parts of the island different building materials are used: magmatic rocks in the area close to Etna Vulcano; metamorphic and argillous in the Messina district, while the inner part (mainly in Enna, Caltanissetta, Agrigento districts, and in some places in Trapani and Palermo) displays the prevailing use of gypsum. The quality of the original materials, however, is different from the industrial one currently available. This raises a certain number of issues. The frequent dismantling of the historical-technological elements brings forth a loss of perception concerning the value and property of these traditional features such as their sustainability characteristics. This paper illustrates the following: research on the recognition process of local gypsum materials and techniques through direct and indirect sources in Sicily’s inner areas (Campisi, 2018, 2020; Mamì, 2007, 2014, 2020); the diffusion of historic techniques on gypsum in Italy and Europe; the principal problems of its recovery and reconstruction of the productive processes; the principal studies on conservation procedures of these techniques.