The Development of a Methodology to Understand Climate-induced Damage in Decorated Oak Wood Panels

Climate-induced damage in decorated oak wood panels is considered to be a high risk for pre-eminent museum collections. To advise museums on the development of sustainable future preservation strategies and rational guidelines for indoor climate specifications, the risk of this type of damage – physical and mechanical is analysed in full depth in this research. A comprehensive methodology is required that meets the requests of the conservation community and also helps to bridge the gap between scientists and conservators. Therefore, this research couples an extensive examination of empirical data obtained from naturally aged museum objects, i.e. a collection analysis, with numerical modelling and experimental testing. A multidisciplinary collaboration has been initiated, whereby conservators and scientists are working together to fulfil the common objectives of sustainable and low-risk preservation of valuable museum collections. In this paper, the methodology is outlined and some results are presented

A controlled method to flatten warped wooden panels

This article describes the research and subsequent treatment to flatten the warped wooden doors of a seventeenth-century cabinet. The aim was to flatten the veneered panels, in very strict climatic conditions and without lifting any veneer or damaging the surface finish of the exterior. In this research, the bending strength and modulus of elasticity of oak, at different temperatures and moisture contents perpendicular to the grain, were determined by experiment. Based on a literature survey, the maximum amount of moisture and heat which was safe to apply was determined. This enabled us to straighten the veneered panels in a very controlled manner

Hygro-mechanical response of oak wood cabinet door panels under relative humidity fluctuations

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

Climate4Wood: climate effects on decorated wooden panels

Damage caused by fluctuations in museum climate is regarded as one of the main risks to museum collections. Therefore very strict standards for climate specifications have developed, leading to high implementation and energy costs. Based on research done since the 1990's, these specifications are now seen as unrealistic and unnecessarily strict, however, extensive research is required to convince the conservation community that these specifications can be relaxed without causing damage to susceptible objects, such as wooden panels (paintings and furniture). The aim of the Climate4Wood proposal is (1) to identify the RH fluctuations that decorated wooden panels can safely sustain (the 'allowable' fluctuations) and (2) in consequence to develop rational guidelines for the climate specifications in the museums. Therefore it is important to understand the response of wooden panels and the damage failure criteria. The project outcome enables the development of a decision-making model that will help museums to become more sustainable, by balancing the cost and preservation of the collection. Based on a museum study (PhD 1), consisting of a systematic analysis of a collection of decorated panels, reconstructions will be made to measure the hygrothermal properties of oak. The results are used as input for a material and mechanical modeling study (PhD 2), to model climate and age induced stresses and deformations. A postdoc will determine and model the relevant non linear elastic material properties. It is expected that combining this information will help museums throughout the world to develop rational guidelines for climate specifications

The development of a methodology to understand climate-induced damage in decorated oak wood panels

Climate-induced damage in decorated oak wood panels is considered to be a high risk for pre-eminent museum collections. To advise mu¬seums on the development of sustainable fu-ture preservation strategies and rational guide¬lines for indoor climate specifications, the risk of this type of damage – physical and mechanical – is analysed in full depth in this research. A comprehensive methodology is required that meets the requests of the conservation com-munity and also helps to bridge the gap be¬tween scientists and conservators. Therefore, this research couples an extensive examination of empirical data obtained from naturally aged museum objects, i.e. a collection analysis, with numerical modelling and experimental testing. A multidisciplinary collaboration has been initi¬ated, whereby conservators and scientists are working together to fulfil the common objec¬tives of sustainable and low-risk preservation of valuable museum collections. In this paper, the methodology is outlined and some results are presented

Assessment of climate induced damage in decorated oak wooden panels

Climate induced damage in decorated oak wooden panels is considered to be a high risk for the preeminent museum collections. To advise museums on the development of future sustainable preservation strategies and to define rational guidelines for indoor climate specifications, climate induced physical and mechanical damage has been analysed in a collection study, experimental testing of mock-ups and by finite element modelling. The collection study consisted of the development of a comprehensive methodology to select objects of interest from the collection and analyse their condition using a combination of visual inspection and archival searches. Mock-up samples of wooden panels with representative structural elements were exposed to varying climate conditions in climate controlled rooms and monitored with state-of-the-art experimental mechanics equipment. Further the collection study and experimental testing were used to inform the development of a finite element model of crack growth under 3-point bending. The work was performed within the Cimate4Wood project, a multidisciplinary collaboration between conservators and scientists work. The paper presents the methodology of the museum study and results from the museum study, experimental testing and modelling.Structural Integrity & Composite