The Green Attitude in Art Conservation: Polyhydroxybutyrate–based Gels for the Cleaning of Oil Paintings

Fully biodegradable novel bio‐based organogels were developed for removing aged protective films from the surfaces of paintings, aiming at providing effective cleaning tools, easily controllable by reducing the solvent permeation into underlying paint layers and not dangerous for human health and the environment. The gels were based on poly‐3‐hydroxybutyrate (PHB) as gelling agent, γ‐valerolactone (GVL) as solvent and triethyl citrate (TEC) as plasticizer. PHB‐gels were able to completely remove protective varnishes on real oil paintings, without affecting the pictorial layer and leaving negligible residues after the application. Moreover, the gels showed good mechanical and handling properties, they were fully composed by non‐toxic ingredients and resulted readily biodegradable in water, therefore easily disposable after the use.