Trä och fukt ? Mätmetoder för fuktrelaterade dimensionsförändringar hos trä och deras användbarhet, med två fallstudier inom konservering
WoodMoistureDimensional changeMeasurement techniquesPreventive conservationThe Vasa museumThe church of Vänersborg
This thesis deals with different methods for measuring moisture-related dimensional changes ofwood. Typically relative humidity is measured to determine if the ambient climate around anobject is harmful to it or not. Values between 40 to 65% RH are recommended for hygroscopicmaterials. To know how a wooden object actually reacts to changes in the surroundingenvironment requires methods that involve the object itself. Because of the wood anisotropy,differences in wood structure, finishes and other restraints, it is not always possible to predict themovements.This paper addresses various measurement methods, primarily methods that have been testedin the field of conservation, with examples of their use. Topics that are discussed are how themethods work, what information they provide and their pros and cons. Two case studies providedetailed examples of some methods, first, the use of electric linear meters in the ceiling ofVänersborg church and second, weighing and shrinkage measurement with callipers on thewarship Vasa.The purpose was not to find the ultimate measurement method, it doesn´t exist, but to exploredifferent methods and their applications. All methods must be combined with measurements ofRH and temperature to create a connection between cause and effect. Different methods giveanswers to different questions and may need to be combined with each other. When selectingthe method of measurement, one must also question the usefulness of the information in relationto any damage to the object.