Experimental methodology to monitor the development of wood drying cracks in real-time

Drying is a fundamental step in solid wood processing, yet it is very challenging because of potential drying defects negatively affecting the final product quality. Successful kiln drying depends largely on the diffusivity and permeability of the wood species. Despite many research efforts, predicting kiln-drying schedules for a given wood species is not yet possible. The main reason is that important spatio-temporal variables such as moisture and temperature gradients, and wood anatomical features are considered insufficiently in the predictive modelling framework. We expect that monitoring and controlling drying up to the limit states can be used for any wood species. To understand the influence of parameters determining these limit states we developed an experimental measurement set-up. This set-up allows real-time monitoring of local moisture content gradient inferred from the electrical resistance gradient, wood temperature gradient and average moisture loss in function of time for any wood species. The obtained data is linked directly to the wood anatomical structure on the end grain, the occurrence of cracks and the transversal shrinkage. This methodology enables to unveil interrelationships between physical parameters and changes of the wood anatomical structure. We present a proof-of-concept with basralocus (Dicorynia guianensis)