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Thermal modification processes significant affect the chemical configuration of the wood matrix improving moisture-related properties and material durability. In addition, the distinctive dark tones of heat-treated timber increase the economic value of several light-colored species. However, these treatments alter the substrates and it could influence the performance of coating products, necessary to maintain the surface features in certain end-use sectors. Ash wood ( Fraxinus excelsior L.) samples industrially treated at 192 °C, 202 °C and 212 °C were coated with decorative waterborne polyurethane and industrial UV-hardened coatings. Afterwards, the samples were subjected to accelerated weathering. The resulting surface topography was assessed with a 3D scanner and a profilometer, revealing slight changes in the texture. Color changes were quantified with hyperspectral imaging by generating surface color maps in CIE Lab coordinates. The results indicate acceptable photostability of thermally modified wood. Changes in wettability, surface free energy, work of adhesion and cohesion were determined by contact angle. Higher hydrophilicity after weathering was observed, but with an acceptable overall performance. At the same time, polar and dispersive shares were redistributed depending on the applied coating. It was demonstrated that heat-treated wood could be an optimal substrate for innovative wood-based products, suitable for use outdoor and exposure to changing weather conditions. [ABSTRACT FROM AUTHOR]

Timber structures can undergo alteration during their service life, which can be caused by mechanical, environmental or biological agents (bacteria, fungi and insects), because of the biological nature of the material. On site characterization of timber members is a very challenging task, especially assuming that both, the structure itself and material used for construction have to be evaluated. Current assessment procedures are limited to visual inspection, occasionally supported by a few instrumental analyses (such as wood moisture content measurement and drilling resistance tests). However, a clear tendency for the application of various non-destructive techniques is observed nowadays. The paper presents an overview on the current applications of infrared spectroscopy for the characterization of various alteration phenomena in wooden artefacts. A literature review is complemented by a series of results, reported from experimental campaigns carried out by the authors. The aim of the paper is to demonstrate the applicability of the proposed method for the analysis of different degradation processes occurring in timber members, with a special attention on wood aging, weathering, biotic decay by fungi and waterlogging. Examples of spectra evaluation as well as limitation of proposed methods are presented. Case studies including classification of decay type, analysis of the weathering dynamic and characterization of waterlogged wooden samples are briefly illustrated. Practical application of spectroscopy within timber structure assessment is considered as a very important supplement to the typical information collected during ordinary tests. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]