Dynamic SANS study of vanish blanching

Paintings are artistic expression in soft materials. Their component polymers, dispersions and emulsions are well-known to soft matter physics and ideally investigated by small-angle neutron scattering (SANS). Working with museum partners, we aim to use SANS to characterize and understand blanching, a leading open challenge in modern conservation. Blanching involves irreversible damage to a painting by exposure to moisture, causing the varnish or paint to become opaque. The structural changes are thought to result from the growth of nanoscopic pores that scatter visible light. The appearance and evolution of these pores is suggestive of spinodal decomposition, working to minimise the interfacial area between a hydrophobic varnish polymer and water infiltrating into its initially invisible pores. SANS is ideally suited to non-invasively characterise this process in real and mock-up samples, providing key observations to feed into models of polymer-solvent interactions to predict blanching damage accumulation. It can also reveal changes in varnish structure before blanching becomes visible, e.g. for mapping out damage risk to inform conservation decisions. In this first proposal of an ISIS Development PhD Studentship on “Art, soft matter and SANS”, we will use SANS to investigate mastic varnish samples prepared and damaged by water immersion ex-situ, vanish samples damaged in-situ by immersion in D2O on the beamline, and mock-up blanched samples provided by gallery partners.