Green Solvents for the Removal of Aged Paints

Varnishes are a ubiquitous component in polychrome works, from the oldest to the most modern. They are applied by the artist as a final coat so that the pictorial layer is sealed and protected from external agents, with the added benefit of achieving a full, saturated color, thereby improving the aesthetic appeal of the image. Like all materials, paints are not immune to the passage of time, leading to the loss of elasticity of the film, transparency and alteration of the colors and, consequently, to opacity, yellowing and difficulty in reading the painting.

The cleaning of this layer therefore becomes essential, removing the layer of varnish and replacing it with a new one. For this operation, organic solvents are commonly used according to the type of varnish to be removed, which, despite their efficiency, are dangerous both for the environment and for the operator’s safety.

Since 2006, Europe has been adopting the REACH regulation (Registration, Evaluation, Authorization and Restriction of Chemicals) which establishes the procedures for the collection and evaluation of information on the properties of substances and the dangers deriving from them. As a consequence, many products have been declared harmful with respect to the new regulation, thus leading to the need to find so-called “green” alternatives to products linked to methods and characteristics of the past. The term “green” is not an absolute definition, the only green solvent is in fact water, it would be more appropriate to define a product greener than another one because there is always a certain percentage of risk in every organic substance. The factors that are taken into consideration to be able to name a product green concern not only the risk factors for health and the environment but also the sustainability related to the entire life cycle of the material from production to disposal (LCA).

Our research focuses on the formulation of new products optimized for restoration that facilitate the application process while being respectful of the restorer’s health and the environment. In particular, we want to test the effect of solvents belonging to the family of acetals and derivatives of other substances from the world of agriculture (specially selected through TEAS and HSP) on natural paints (dammar, mastic) and synthetic paints (paraloid, retoucher) artificially aged. The cleaning operations will be controlled by colorimetric analysis and UV fluorescence by means of multispectral imaging in order to verify the effective removal of the paint with attention to the phenomena of leaching and swelling of the oil binder of the paint. Finally, the presence of residues will be monitored by FTIR.

 

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