Identification and degradation atlas of plastic objects in the collections of the Musée des Arts Décoratifs, Paris

Abstract Plastics, omnipresent in 20th-century museum collections, pose major conservation challenges due to their often rapid, irreversible degradation. At the Musée des Arts Décoratifs (Paris), nearly 12,000 plastic objects raise urgent concerns. This study establishes a degradation atlas based on polymer identification and condition assessments of 142 representative objects, using ATR-FTIR spectroscopy supported by micro-analyses. Results highlight the predominance of polyvinyl chloride (PVC) and polyurethane (PU), often combined with polyethylene (PE) and polystyrene (PS) in composite objects. PU is the most vulnerable, particularly in fashion objects, where degradation leads to sticky surfaces and delamination. PVC primarily exhibits yellowing and plasticizer migration, while PE and PS are generally more stable. Composite objects pose additional challenges due to incompatibilities. Degradation is most severe in objects from the 1960s-1990s. By linking materials to alterations, the atlas and database provide conservators a practical reference tool to improve preventive strategies, staff training, and long-term monitoring.