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Atmospheric pressure plasma was used to deposit thin layers of copper and aluminium micro-particles on the surface of Scots pine sapwood (Pinus sylvestris L.) boards. Three different loadings of metal particles were established. Additional wood boards were topcoated with a commercial acrylic binder. Boards were exposed to natural weathering for 18 months. Discolouration of copper-treated boards was slowed down, and the treatment at highest loading displayed the best appearance. Aluminium treatment was not sufficient to prevent or reduce discolouration. The application of an acrylic binder as topcoating enhanced the general appearance of metal-treated boards. Evaluation of treated boards did not reveal any reduction in crack formation or water uptake due to the particle deposition. Infrared spectroscopy suggested that copper does not protect lignin from photo-degradation. Nevertheless, copper treatment reduced fungal infestation on wood; at highest copper loading, blue stain did not penetrate through the treated surface.

Thin layers of copper micro-particles were deposited on the surfaces of Scots pine ( Pinus sylvestris L.) micro-veneers using atmospheric pressure plasma to improve the resistance of the surfaces to weathering. Three different loadings of copper were established. Micro-veneers were exposed to artificial weathering in a QUV weathering tester for 0, 24, 48, 96 and 144 h following the standard EN 927-6 [1] . Mass losses after each exposure showed significant differences between copper coated and untreated micro-veneers. Tensile strength was assessed at zero span (z-strength) and finite span (f-strength) under dry conditions (20 °C, 65% RH). During 48 h, micro-veneers lost their z-strength progressively. In contrast, copper coating at highest loading imparts a photo-protective effect to wood micro-veneers during 144 h exhibiting z-strength retention of 95%. F-strength losses were similar in all copper treated and untreated micro-veneers up to 96 h. However, after 144 h, copper coated micro-veneers at highest loading showed significantly greater strength retention of 56%, while untreated micro-veneers exhibited only 38%. Infrared spectroscopy suggested that copper coating does not stabilize lignin. Inductively Coupled Plasma revealed that micro-veneers coated with the highest loading exhibited the lowest percentage of copper loss. Blue stain resistance of copper coated Scots pine following the guidelines of EN 152 [2] was performed. Additional test with different position of the coated surface was also assessed. Copper coating reduced fungal growth when coated surface is exposed in contact with vermiculite. Spores of Aureobasidium pullulans were not able to germinate on the copper coated surface positioned uppermost.

Laboratory choice and no-choice tests following the guidelines of EN 117 (2013) were performed to assess the resistance of wood modified with short- and long-chain amino-functional siloxane emulsions to subterranean termites (Reticulitermes flavipes). Scots pine sapwood was vacuum-pressure treated to reach 2, 5 and 8 % weight percent gain. Half of the specimens (including controls) were subjected to an accelerated aging test according to the standard EN 84 (1997) prior to termite testing. In addition to visual rating, mass losses were also determined. In case of the no-choice test, silicone-treated samples were not resistant according to EN 117 (2013), even though a clear reduction in mass loss had occurred. After exposure to a choice test, the modified wood samples showed 5–10 times less mass loss than control samples, even in the case of the leached specimens. This study reveals a good performance of wood modified with short-chained amino-functional siloxanes in resisting to R. flavipes when there is a choice of feeding.