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Understanding how the evolving molecular composition of an oil paint layer on its transition to an aged solid film affects its dimensional change and mechanical properties is fundamental to the assessment of material durability and more broadly risk of degradation of oil paintings. Tensile properties—modulus of elasticity and strain at break—as well as cumulative shrinkage were determined for a selection of oil paints from Mecklenburg’s Paint Reference Collection now after approximately 30 years of drying. The oil paints were found to get stiffer and more brittle with diminishing plastic deformation and increasingly elastic behaviour. For some paints, the increases in stiffness and decreases in the strain at break were dramatic during the late stage of drying. The observations modify the current physical model of paintings in which the mismatch in the response of glue-based ground layer and unrestrained wood or canvas support to variations in relative humidity (RH) has been identified as the worst-case condition for the fracturing of the entire pictorial layer. This study demonstrated that some paints were more brittle than the glue-based ground layer and as a consequence more vulnerable to cracking. The shrinkage of paints due to molecular relocation and/or evaporation of organic medium as they dry and age was measured. This shrinkage can exceed their strain at break and lead to fracturing of the oil paint layer if it is restrained by a dimensionally stable substrate. Consequently, after long-term drying, the cumulative shrinkage can cause oil paints to crack even in absence of fluctuations in RH or temperature. An example of cracking developed in an oil paint layer on the top of an undamaged ground layer in a historic panel painting was made evident by the X-ray microtomography.

In recent years there has been growing interest in the development of devices and software packages that allow museum decision-makers to manage the environmental conditions in collections and estimate the evolution of degradation of objects. A system able to monitor the environmental conditions but also to provide warnings and recommendations about failure boundaries would optimize conservation actions and strategies thus ensuring proper conservation of the collections in the long term. CollectionCare project aims to develop an innovative and affordable decision support system for the preventive conservation of cultural objects in small and medium-sized museums by combining research and technological advances in monitoring systems (sensor nodes), wireless communications, cloud computing, big data, and material degradation models. Validation and demonstration activities for the CollectionCare system will be carried out in six different European museums. To this end, communication efforts will be developed to promote the importance and applicability of these technologies in the conservation of cultural objects. All this in order to increase citizens’ awareness of the importance of preventive approaches for the conservation of the European cultural heritage.