Preserving plastics in the collection at the Harvard Art Museums

Abstract

In 2016, the Harvard Art Museums began the first comprehensive survey of polymeric materials in the collection, finding almost 500 objects. The survey sought to determine the scope of plastics in the collection, to identify the polymer through the tandem use of FTIR (Fourier transform infrared spectroscopy) and pyrolysis-GC-MS (Gas Chromatography Mass Spectrometry) and to implement a conservation plan. The bulk of the conservation work is preventive, focusing on improving storage conditions. Positive results have already been observed: a polyvinyl chloride object sealed in Mylar® polyester film reabsorbed all the pools of plasticiser that had migrated to the surface. Interventive conservation forms a smaller portion of the work, and the treatment of a regenerated cellulose book cover is presented. Mock-ups determined Aquazol® (Poly(2-ethyl-2 oxazoline)) was the best adhesive, one-ply goldbeater’s skin the most appropriate backing material, and Mylar® with goldbeater’s skin adhered with isinglass the best fill to match the aged plastic. To allow a water-based adhesive to work, the surface of the Mylar® was chemically modified.