Two case studies of unsaturated polyester composite art objects

Three dimensional art objects and parts of installations made of composite materials containing gypsum, fibreglass and two-component unsaturated polyester (UP) resins in the collections of Oulu City Art Museum, Finland, were studied. Even if composite materials are considered to be chemically resistant, the artefacts made of UP composites have started to undergo degradation processes. The aim of this pilot project was to study the causes of degradation of the composite materials. Ageing and degradation tests and analyses were employed to reveal their effect on unsaturated polyesters. To determine the chemical composition and colour changes of the tested materials, samples were analysed before and after ageing using FTIR and CIE L*a*b* colour measurements. Analyses of this preliminary study have shown that there are differences in quality, curing and ageing properties of different UP composites. This information was found to be important in developing conservation strategies for art objects made of UP composites.