Digging into the past of nature carpets. The evaluation of treatments on artworks by Piero Gilardi made from polyurethane ether foam.

This study evaluates two research projects and treatments performed ten and twenty years ago by the Cultural Heritage Agency of the Netherlands (RCE) on two artworks made of flexible polyurethane ether foam (PUR foam) by Piero Gilardi; Natura Morta (1967) of the collection of Museum Boijmans Van Beuningen, Rotterdam (NL) and Zuccaia (1991) of the collection of Zoetermeer City hall (NL). These projects and treatments on the objects involved the treatment of mechanical damages present in the works, and the development and performing of the consolidation of PUR ether foam with Tinuvin B75/Impranil DLV mixture. The condition of an untreated nature carpet Cavoli e Neve (1967, 1988) from the collection S.M.A.K., Gent (BE) was used as a control reference in this study. The techniques from the two former RCE researches, such as determination of cell strut size and hydroxyl index, are used for the evaluation of the effectiveness of the past treatments. Besides that, empirical research, i.e. resilience and rubbing tests, are performed on all case studies. Also, the consolidation method used in the treatment of the abovementioned artworks was evaluated and refined. Finally, consolidation tests on artificially aged and severely degraded PUR-foam samples were carried out to see whether the condition of already degraded foam could also be reinforced. This study showed that the effectiveness of the former treatments was best assessed by the measurement of the cell strut size and empirical research. The past treatments proved to be very successful and can therefore be suggested for similar artworks. After the promising results of this study, Cavoli e Neve was treated. However, preliminary consolation tests on the artwork itself showed, viewing the foam under microscope, the skeleton still broke during consolidation and therefore did not improve the skeleton strength. Therefore, besides cleaning the work and structural treatment of the damages, a consolidation on this artwork was not performed. Ongoing research will focus on this issue.