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.

Study of Materials and Technique of Late Baroque Stucco Decorations: Baldassarre Fontana from Ticino to Czechia

“…The main difference is the bas-relief technique used by Fontana and the absence of aggregate in the finishing layer. This characteristic of the finishing layer has also been observed in some works by other authors, such as the Casella and the Colomba family, while the Silva family, Giovan Battista Barberini, and Isidoro Bianchi also added marble powder [15,24]. The use of casein or milk was also found in other stucco artworks [24].…”

“…For the realization of the stuccoes that were analyzed, lime and gypsum were used as binders, and calcite/marble fragments or river sand as aggregate. Lime in Ticino was historically obtained from the firing of dolomitic limestones, which are characteristic of the area [22], and therefore a magnesium component is often found, even if in variable percentages [23,24]. The closest gypsum quarries are located on Lake Como, at Nobiallo and Limonta (Italy), or at Melide, Rogno-Campione, and Meride, in Switzerland [25].…”

A Case Study of Renaissance Wall Paintings in Granada (Spain): Historical–Artistic Analysis, Materials Characterization, and State of Conservation

“…This poor state of conservation is due to the 19th century Napoleonic invasion, recent historical events and state of abandonment, as well as the impact of different degradation agents that have worsened the situation [26]. After the naked-eye examination of the paintings, which allowed us to develop a first diagnosis, humidity appears as one of the main causes of decay, driving certain chemical reactions that modify the composition of the painting compounds [4,10,[52][53][54][55].…”

Mortars and plasters—how to manage mortars and plasters conservation

“…However, the use of water must be kept to a minimum to limit segregation, shrinkage, and the formation of microcracks. Water is also dangerous for some sensitive materials (e.g., gypsum or clay or other components of stucco artworks) or in case of contamination by soluble salts, they can be reactivated (Caroselli et al 2020). To reduce the need for water in the grouting mix, superplasticizers are usually added.…”