This paper presents research that was conducted to investigate the interpretation of glass transition temperature in the context of conservation. The results of thermomechanical and bulk mechanical properties of Araldite EA1253 epoxy and Resin WTM poly(vinyl acetate) (PVAc) are reported. Both adhesives are used in painting conservation and represent two generic types used within conservation. The adhesives were also tested with the addition of fillers. The thermomechanical techniques employed were Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC). Frequency dependency, sample configuration, and moisture sensitivity were investigated. Bulk tensile testing was performed at temperatures on either side of the glass transition onset, calculated from DSC data. Comparisons were made between data from DMA, DSC, and tensile testing. The results highlight the inherent ambiguities in the interpretation of thermomechanical data (in particular, a difference of at least 15oC between the onset of the change in DMA storage modulus and the ductile/brittle transition compared to the Tan delta peak value), and the implications this has for conservation treatments. The use of the data to predict the physical properties of the unfilled and filled adhesive is demonstrated. It is suggested that a more consistent and sophisticated use of thermomechanical data would be of benefit to conservation practice.