Application areas of synchrotron radiation tomographic microscopy for wood research

Possible applications for synchrotron radiation tomographic microscopy in the field of wood research were tested and evaluated at the TOMCAT beamline (TOmographic Microscopy and Coherent rAdiology experimenTs) at the Swiss Light Source (SLS) at the Paul Scherrer Institute (Villigen, Switzerland). For this study, small cylindrical samples (∅ 1 and 3 mm) were examined with different experimental setups resulting in a nominal voxel size of approximately 1.48 × 1.48 × 1.48 and 3.7 × 3.7 × 3.7 μm³, respectively. Suitability of the TOMCAT microscope for 3D investigations of wood anatomy was tested on several softwood and hardwood species revealing microscopic features (e.g. tyloses, wall thickenings or pits) down to the nominal pixel size. The results suggest that even features in the sub-voxel range can be made visible. Tomographic microscopy was also tested for wood technological applications, i.e. penetration behaviour of a wood preservative and also of three wood adhesives (poly-urethane resins) with different viscosities. Although the experiments with the preservative yielded no clear results, the method seems suitable for examining the penetration of the different adhesives. The adhesive penetrates the wood mainly by the vessels where it can be easily discerned from the wood structure.