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Beech (Fagus sylvatica L.), oak (Quercus robur L.) and pine (Pinus sylvestris L.) wood were volume-densified by means of thermo-mechanical modification. At first stage the wood was heated in a hydraulic press at temperature 100°C for 720 s, and then one-step densified in order to obtain the target thickness. The wood was cooled in a hydraulic press with unheated plates. Density profiles parallel and perpendicular to the grain were examined. The analysis of the density profiles was carried out on the basis of the following parameters: mean density, minimum to mean density ratio, maximum density, and the distance between the maximum density area and the wood surface. Wood hardness was determined according to the Brinell method. Volume-densified pine wood was characterized by considerably lower susceptibility to densification than beech or oak wood. Densified beech wood had the highest mean density 921 ±7 kg/m³, and the highest maximum density 968 ±12 kg/m³. The Brinell hardness of densified beech, oak and pine wood was twice as high as before the densification. The greatest hardness after the densification 78.60 ±10.56 N/mm² was observed in beech wood. [ABSTRACT FROM AUTHOR]

The study examined the effect of UV radiation on the colour and wettability of cedar, gaboon, meranti and Scots pine wood. The tested species of exotic wood are mainly used in European countries for facades. For this kind of usage they act as a substitute for pine wood. In the study, the colour parameters were determined using the CIE L*a*b* colour space model. The tests showed that the most significant changes in the lightness of the wood occurred after 20 hours of UV radiation exposure. After that time, the L* value change was linear. The cedar wood turned the darkest and it also showed the greatest total change of colour ΔE. Comparable colour changes ΔE, and thus the greatest colour stability of all the tested wood species, were shown by the gaboon and meranti. In addition, it should be noted that all the tested wood species were characterized by a much smaller susceptibility to colour change under UV radiation than the pine sapwood and heartwood. The results also revealed that UV radiation significantly affects the contact angle, and therefore the surface free energy of the cedar and pine sapwood. [ABSTRACT FROM AUTHOR]