Hélène Aureli

This study investigates the potential of fatty acid methyl esters (FAME) as environmentally sustainable alternatives to traditional solvents for the removal of low-polarity materials commonly found in cultural heritage artefacts. Recognizing the environmental and health concerns associated with conventional solvents, this research focuses on FAME to remove low/non-polarity or non-polar substances used in cultural heritage preservation. Laboratory samples coated with low molecular synthetic resins (LMW) such as Regalrez 1094 and microcrystalline wax were treated with FAME applied in gel to prevent solvent–substrate interactions. Photographic documentation under UV-vis light, optical microscope observations, and spectrocolorimetric analysis were used for assessing surface “cleanness”, while FTIR-ATR spectroscopy was used to detect possible residue from treatment. Moreover, SEM analysis was used for a better understanding of the results. The best results were obtained using FAME base on methyl stearate according to Hansen-RED.

In spite of the application of different cleaning procedures, the marble used for the portrait bust of Queen Margherita di Savoia continued to show permanent discoloration, consisting of an unevenly distributed grayish alteration, mainly on the front part. In this work, a multi-analytical, non-invasive approach was proposed using spectrocolorimetry, reflectance spectroscopy and multispectral imaging. The initial assumption, suggesting the presence of altered protective materials based on organic products (such as waxes or oils,) applied in the past according to traditional practices, was excluded, revealing instead the presence of deposits of particulate matter, which penetrated inside the crystalline structure of the marble, leading to a variation in its shade. Cleaning tests were also carried out to define the best product, using sustainable chemicals such as Polar Varnish Rescue^®, alkoxyde surfactant, disodium EDTA, GLDA and Politect^® Base in order to identify the best methodology and materials for sustainable cleaning, respecting the integrity of the original matter. Politect^® Base demonstrated better action in comparison to the other products tested, and similar results were obtained with GLDA, which could be applied in areas where the Politect^® is less efficient (e.g., lace).

In this study, the investigation of the oil painting on canvas I Tesori del Mare made by Plinio Nomellini in 1901 is presented. The aim of the research was threefold: the examination of the state of conservation in view of the restoration treatment, together with the identification of the causes of degradation and the study of the artistic technique. During the years, the artwork underwent several cleaning and fixing interventions, resulting in a patchy appearance of the surface. Nevertheless, the presence of consistent liftings persists, while the protective coating shows uneven chromatic alteration, both requiring further analysis. Multispectral imaging allowed for better visualization of the figuration’s structure and the restored areas. The combined use of Raman spectroscopy, Fourier Transform Infrared spectroscopy in the Attenuated Total Reflection mode (FT-IR ATR), and Scanning Electron Microscopy coupled with an Energy Dispersive Spectroscopy (SEM/EDS) enabled better understanding of the stratigraphy through the identification of some pigments, the binder, and the aged varnish layer on the top. SEM/EDS highlighted the presence of zinc in both the ground layer and the paint layers. Furthermore, FT-IR ATR spectroscopy showed peaks related to metal soaps such as zinc stearate, which are known to cause severe delamination of the paint layers, explaining the recurring lifting issues. Eventually, the varnish layer was found to be acrylic resin, presumably mixed with varnishes applied in past restoration treatments.

This paper describes the multi-analytical approach implemented for the study of the oil painting Il Venditore di Cerini made by Antonio Mancini in 1878. The research was carried out to characterize both the original stratigraphy and the alleged non-original varnish on the surface. SEM/EDS analysis showed the presence of pigments already detected in other paintings by Antonio Mancini. Multispectral imaging, DinoLite microscope, and FT-IR ATR spectroscopy revealed significant data regarding the invention of the “graticola” method—a technique implemented by Mancini to respect the proportions of the figures—also proving the presence of an aged layer of non-original shellac on the surface. The yellow/brownish tone of the varnish was hiding the real shapes of the figure, requiring a selective removal of the aged coating. The proposed cleaning systems were chosen among the green chemical alternatives present in the market, aiming at promoting a sustainable development in the Cultural Heritage field. The selection was made according to the Fd parameter of the cleaning systems—which defines the energy from dispersion forces between molecules—in relation to what is defined in the literature as the suitable Fd value for the removal of the shellac. The best-performing green cleaning system proved to be the Polar Varnish Rescue GEL—a gelled acetals mixture developed by YOCOCU APS—for its effectiveness in selectively remove the aged shellac while preserving the integrity of the original stratigraphy.