Composition and techniques of the Ticinese stucco decorations from the 16th to the 17th century: results from the analysis of the materials

Abstract

This work investigated the techniques used for creating a three-dimensional stucco decoration. During the multidisciplinary project "The art and industry of Ticino plasterers from the sixteenth to the seventeenth century", some stucco works mainly situated between the south of the Ticino region and the province of Como were studied. These artists traditionally known as "Masters of the Lakes", were invited across Europe to decorate the most important architectures at the time. The diffusion of this art and in particular of these workers was probably due to their unique ability to master the complex art of stucco. In particular, the scientific research was addressed at understanding the structure, composition and original “recipes” of the high relief stucco and statues, by using different complementary analytical techniques: the internal structures were analyzed with the radiographic technique, the mortars were characterized by polarized light microscopy, SEM–EDS and FT-IR spectroscopy. The identification of organic additives was possible thanks to a pre-treatment sample with the reactive sulfur tetrafluoride gas (SF4). Our results indicated that the stucco works of the considered authors were made using almost all recurring components, although differences emerged in the assembly of the internal structure, in the presence of gypsum in the ground mortar layers and in the use of the aggregate in the finishing.