Sustainable conservation treatments for large-scale artworks made of polyurethane ether foam in art and design
Working with large scale polyurethane ether in art and design
Yvonne Shashoua / Louise Cone
Summary of the paper
Polyurethane (PUR) foams have been among the most popular plastics used by artists and designers since the early 1960s. However, PUR ether foams are industrial materials and therefore designed to function for less than 10 years. They react chemically with oxygen to discolour, collapse and eventually crumble. Once registered in collections, museums are legally obliged to preserve the physical properties and artistic intent of artworks and objects for future generations, at least 50 years. This poses a challenge for museum professionals. Conservation treatments for degraded PUR foams aim to strengthen and consolidate weakened foams so that they can withstand handling and resist further degradation.
To date, there is only one evaluated and established conservation material that has proved effective in consolidating and coating crumbling PUR ether foams. It was developed in 2011 at the Cultural Heritage Agency of the Netherlands (T.van Oosten, PUR Facts, conservation of Polyurethane Foam in Art and Design, Amsterdam University Press, 2011, ISBN: 978-90-8964-210-3). However the consolidant, Impranil DLV solution, a polyester/polyether-urethane dispersion of aliphatic isocyanate from Bayer, contains toxic chemicals, which require that it must be sprayed or nebulized in an enclosed area fitted with air extraction facilities. These health and safety issues are difficult to comply with when working with large-scale PUR works of art or design pieces.
During a two-year project, completed in March 2017, water-based protein and carbohydrate solutions and acrylic dispersions were applied to new, thermally and photolytically aged model rigid and flexible foams and their appearance, texture, friability, recovery from impact and chemical stabilities evaluated and compared with those treated with Impranil DLV. Effective consolidation required pre-treatment of PUR foam surfaces to increase its surface energy using ethanol. Within the framework of this study, considering the visual and physical performances of all the materials evaluated, it may be concluded that Aquazol 500 (1.5%) and Agar (0.5%) offer superior consolidation, more sustainable and less toxic alternatives to Impranil DLV when applied by spray to soft foams. By contrast, Plextol B500 performed best on hard foams, although they were more complex to treat and to evaluate than soft.
The present research suggested that UV radiation was more damaging to PUR ether foams that previously understood and that modelling degraded PUR foam using accelerated light ageing produced more highly degraded foams than real time. The cell walls of foams that underwent accelerated light ageing were more disrupted than those observed in real artworks in Danish museums.
