Assessment of aqueous cleaning of acrylic paints using innovative cryogels

Waterborne acrylic paints have been widely used by artists since their development in the late 50s. Their cleaning, i.e., the removal of mainly airborne dust and grime, is a challenging operation, because acrylics are very sensitive to solvents in a wide range of polarity. Even if aliphatic and low-molecular weight aromatic hydrocarbons are less prone to interact with the hydrophilic components of the acrylic paint layer, the use of water is necessary since it grants better cleaning performances. In this paper, three acrylic commercial paints from Liquitex® (USA) were selected and characterized using Fourier Transform Infrared spectroscopy (FT-IR) and pyrolysis - gas chromatography - mass spectrometry (Py-GC-MS). The removal of artificial soil from these paint films was carried out using novel highly retentive PVA-based cryogels that have been recently developed to avoid the uncontrolled wetting of water-sensitive artistic surfaces. Their cleaning efficiency was evaluated using Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). Finally, an ATR-FTIR and 2D FTIR Imaging study about the residues left by the gels was carried out by comparing the cryogel with a Velvesil Plus® emulsion, a gel-like silicone polyether copolymer used in the recent past to create a stable water-in-oil emulsion, and still available on the market to conservators. In conclusion, the cryogel granted a safe and satisfactory cleaning action and a residue-free soil removal from acrylic paint films, overcoming the drawbacks of traditional cleaning methods.