Indoor climate fluctuations are regarded as one of the major risks for the emergence of damage in historical works of art. For a safe preservation of their art objects museums try to minimize this risk, which is typically done by imposing strict limitations on the indoor temperature and humidity conditions. The high energy demand resulting from this approach, however, undermines the aim of preeminent museums to execute a sustainable preservation strategy of their collections. A rational improvement of this aspect asks for detailed information on the history of museum objects, complemented by a thorough comprehension of the failure and deformation behaviour of museum objects under indoor climate fluctuations. Accordingly, in this paper the hygro-mechanical response of mock-ups of historical Dutch cabinet door panels made of oak wood is examined under several relative humidity variations. In specific, the mock-ups were subjected to (i) an instantaneous decrease of 40% relative humidity, (ii) eight successive, instantaneous drops of 5% relative humidity, and (iii) a varying relative humidity profile ranging between 35 and 71%. The shrinkage characteristics of mock-ups are translated to their damage susceptibility using an analytical hygro-mechanical bi-layer model. This model shows that restrained hygral shrinkage may originate from: (i) a difference in moisture content across the thickness direction of the panel, or (ii) a directional difference in the coefficient of hygroscopic expansions of structural components forming a coherent connection. The first type of shrinkage occurs in the outer regions of the panel thickness, while the second type of shrinkage takes place at the cleated ends. Further, by accounting for the age-dependency of the fracture strength of oak wood, a clear distinction can be made between the damage susceptibility of new door panels and historical door panels present in museum cabinets. The six main conclusions of the experimental study-conveniently summarized at the end of this paper-provide a scientific basis for the understanding of shrinkage cracks and dimensional changes observed on decorated oak wooden panels in historical Dutch cabinets, and thus may assist in advising museums on future sustainable preservation strategies and rational guidelines for indoor climate specifications.

[heading]Museum objects are often highly complex and composed of materials with varying properties, some of which may have changed as a result of ageing and/or conservation treatments. Research into defining sustainable environmental conditions by balancing energy cost and risk to these vulnerable objects, has mainly focused on experiments in laboratories with new, single materials or on computer modelling, but only to a limited extent on actual objects. This paper presents a method to collect empirical data from a large group of decorated wooden panels in order to investigate the effects of humidity fluctuations on these objects and relate them to their material properties and construction. Wooden panels were chosen as they are regarded to be particularly sensitive to fluctuations in relative humidity. The fluctuations may cause the wood to shrink and swell and can result in open glue joints, cracks and deformation of the panels as well as losses and cracks in the decorative layers. Empirical data are scarcely available as yet but are essential to study relationships between material properties, type of construction, damage and as input and validation for modelling and experimental studies. The method, referred to as the Rijksmuseum Study, was performed on a group of 300 objects from the furniture and paintings collections of the Rijksmuseum.

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