Binary mixtures of ethylene containing copolymers and low molecular weight resins: a new approach towards specifically tuned art conservation products

Painted face artworks often require adhesives during their conservation treatment. Damage or ageing processes that result in cracking, powdering, lifting or similar phenomena can occur, at the interface between two paint layers or between a paint layer and the support. Adhesives need to be applied without compromising the original appearance of the object. Those products can either be formulated to provide structural strength at the interface or be applied more diluted, so that they can penetrate into a weakened porous material to improve cohesive bulk properties strength. In the latter case the adhesive is typically referred to as a consolidant. Since this is a niche sector, only a few formulations are tailored specifically for restoration, while almost all products used are transposed from various commercial fields. Furthermore the notion of reversibility limits the range of polymeric materials for conservation to chemically stable thermoplastics, because they can be safely removed. This paper introduces the results of an international project which aims at characterizing the behavior of new adhesive formulations with tuned physicochemical properties and enhanced stability. These are binary mixtures, based on ethylene copolymers and four classes of tackifier. On the contrary of urea-aldehyde and hydrogenated hydrocarbon resins, ketone and rosin ester resins showed good miscibility with the polymeric component. Nevertheless, all tackifiers investigated were able to modify copolymers properties.