Multi-Analytical Investigation of the Oil Painting “Il Venditore di Cerini” by Antonio Mancini and Definition of the Best Green Cleaning Treatment

This work shows the results obtained from the multi-analytical investigation of the oil painting “Il Venditore di Cerini”, made in 1878 by Antonio Mancini. The aim of the research was twofold: the characterization of the constituent materials of the artwork – with a focus on the alleged non-original aged varnish – and the application of newly developed green solvents for the removal of film-forming substances. SEM/EDS analysis showed the presence of pigments already detected in other paintings by Antonio Mancini [1]. Multispectral imaging, DinoLite microscopy, 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 [2] – also proving the presence of an aged layer of non-original shellac on the surface [3]. The yellow/brownish tone of the varnish was hiding the real shapes of the figure, requiring a selective removal of the aged coating. Indeed, the multi-analytical approach implemented enabled the acquisition of significant elements to characterize the stratigraphy and the constituent materials of the painting, also guiding the cleaning treatment performed on the artwork. The selection and implementation of potentially well-performing cleaning systems were selected among sustainable alternatives available in the market, in compliance with the guiding criteria of Green Chemistry [4]. The tested cleaning systems are: Green Varnish Rescue (acetals’ mixture) in both the liquid form and thickened using hydroxypropylcellulose (Klucel® G), Polar Varnish Rescue (anionic surfactant and acetals) thickened with Klucel® G, and Nanorestore Cleaning (nanostructured water-based fluid with anionic surfactant and mixture of 1-pentanol, ethyl acetate, and propylene carbonate) [5,6,7]. These products were compared with ethanol absolute anhydrous and deionized water. 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 shellac [8]. 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. The reason for its effectiveness is twofold: the Fd value of the product, which is similar to the Fd known to be used for the removal of shellac, and its tendency to establish hydrogen bonds, which plays a significant role in the solvation of shellac. The Polar Varnish Rescue GELcan be easily applied, showing a good degree of solubilization and overall valuable qualities for cleaning treatments on works of art. Most importantly, it represents an alternative to more toxic solvents that are still widely used in the conservation field, since its components are known to be green chemicals capable of safeguarding both human health and the environment. Indeed, the present study aimed at promoting the use of new green materials for conservation purposes which can be easily and effectively used by restorers, fostering sustainable development.