Characterization of Bernini’s Mural Drawing Preserved in Palazzo Chigi in Ariccia (Rome) Using a Multi-Analytical and Chemometric Approach

The characterization of the materials constituting artistic and archaeological artifacts is a crucial issue for many aspects related to their conservation, authentication and restoration. [1, 2] The use of non-invasive or micro-destructive diagnostic techniques is essential to provide restorers, conservators, art historians and archaeologists information about the state of conservation, the execution technique, and finally to define the presence of degradation products [3, 4]. It is known that cultural heritage materials undergo natural and continuous aging, which can be due to both environmental factors (e.g., high moisture, high temperature, etc.) and anthropic factors (e.g., the degradation of materials used in previous restoration/consolidation processes, etc.) [5, 6]. The least invasive approach for the analyses of artworks materials is undoubtedly the non-destructive one, allowing to obtain information without the need of sampling; alternatively taking a micro-sampling may be an option, only when it is strictly necessary [6–8]. Considering the large variety of materials constituting cultural heritage, the use of a single diagnostic technique is often not enough to achieve a comprehensive characterization of composite materials, while the integration of multiple complementary techniques was always demonstrated to be a successful approach [9–12]. In this field, one aspect to take into consideration is related to the immovability of the artworks (e.g., frescoes, wall paintings, statues) as well as their positioning within the arrangement environment (e.g., heights, hypogeum environments, narrow environments etc.,). Therefore, the possibility of being able to use portable instrumentation, which is, at the same time, lightweight and easy to handle but offering performances almost comparable to laboratory instrumentation, became a fundamental requirement [13–15]. Usually, multispectral imaging techniques are firstly performed to identify inhomogeneities of the surface [3, 10], to achieve the spectral behaviour of the used pigments [8, 10], to reveal underdrawings and pentimenti [10] and to guide further spectroscopic analyses along smaller areas (i.e. squared millimetres). Among these spectroscopic techniques X-ray fluorescence, Raman spectroscopy, Laser-Induced Fluorescence (LIF) and Fourier Trasformer Infrared Spectroscopy (FT-IR) are the most used ones to detect the chemical composition of the materials [3, 4, 10, 13, 14]. In the case of measurement campaigns carried on in museums open to the public, such as Palazzo Chigi of Ariccia (Rome), logistic aspects, related to the instrumentation’s bulk and the safety of visitors, must considered, specifically when ionizing/ laser radiation and electromagnetic fields are used [16]. In this chapter, the diagnostic approach applied by using a multi-laboratory and multi-techniques campaign onto the Bernini’s mural drawings “St. Joseph with the Child” preserved in Palazzo Chigi of Ariccia (Rome) (showed in Fig. 1) is described. A detailed description of the artwork is reported in Chap. 1 of this volume. This case study represents a clear example of the adoption of ad hoc logistics solutions for the study of an unmovable artwork. Such a successful approach was further used during the ADAMO project to support the conservation of Vincenzo Pasqualoni’s fresco at the Basilica of S. Nicola in Carcere, in Rome.