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 ideal for investigation by SANS. Working with London museums, we aim to use SANS to characterize and understand blanching, a leading open challenge in modern conservation. When exposed to water, many traditional varnishes suffer irreversible damage and become opaque. The corresponding changes to their structure are caused by the growth of nanoscopic pores that scatter light. The appearance and evolution of these pores is suggestive of spinodal decomposition, minimising the interfacial area between a hydrophobic varnish polymer and water invasion into its initially invisible pores. SANS can non-invasively probe this process, providing key observations for 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. Here, we build on preliminary work to understand blanching as part of an ISIS Development PhD Studentship on “Art, soft matter and SANS”. We have demonstrated that blanching is readily observable on Sans2d, with two distinct timescales: water invasion followed by structural changes that continue over weeks. In this proposal, we aim, through a series of SANS measurements to probe these two processes, to provide a comprehensive view of varnish blanching.