Roughness of machined surfaces of wood has been studied for a long time, since it is an important measure for evaluating the machining process employed and the quality of machined products. It is, however, not so easy to measure or evaluate the roughness, because the surface texture of wood is composed of anatomical roughness as well as the roughness due to processing. This paper introduces the outline of the standards for roughness measurement that have recently been revised completely. It also reviews the studies of the latest decade on roughness evaluation of machined surfaces of wood from the points of view such as roughness measurement including signal processing, evaluation of roughness due to processing, and roughness evaluation based on tactility.

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Using a single trunk of Acanthopanax sciadophylloides whose height was 13 m and age was 35 years, the variation patterns of average vessel element length (VEL), average earlywood vessel diameter (VDe), average vessel diameter at the center of the annual ring (VD), the number of vessels in a transverse section of 1 mm² (VNb), the average ray area (RA), the average ray height (RH), the average ray width (RW), and the number of rays at a tangential section of 1 mm² (RNb) were studied for each annual ring and for each tree height section, based on 7 discs. The maturity age of xylem material was estimated in addition to the study of the horizontal variation patterns. Furthermore, the distance from the top of the tree trunk for each time of annual ring development was estimated based on the tree height growth function estimated from the Gompertz function, and the relation between the distance from the tree top and each element is discussed. As a result, VEL and VD showed similar values as long as the distance from the tree top was almost the same, while RA, RH, and RW showed similar values provided the ring number from the pith was almost the same for a certain annual ring number. These results indicate that VEL and VD are influenced by the distance from the tree top and RA, RH, and RW are strongly influenced by the cambium age.

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A strand-particle board (SPB) was manufactured using unoriented strands for the surface layers and unoriented particles for the core layer. Todomatsu (Abies sachalinensis) strands, recycled waste wood particles, and emulsifiable methylene diphenyl diisocyanate (EMDI) as a resin adhesive were used. The effect of resin content (3 and 6%), surface moisture content (5, 10, 15 and 20%) and press temperature (170, 200 and 230°C) on physical properties, and the effect of resin content (10%), surface moisture content (20%) and press temperature (170, 200 and 230°C) on blisters were investigated using laboratory boards. The results are summarized as follows :
1)A suitable manufacturing condition for the EMDI bonded SPB was found to be a press temperature of 230°C, a resin content of 6%, and a surface moisture content of 15%. This condition produced the most superior properties, namely a board density of 0.62 g/cm³, an internal bond of 0.93 MPa, a modulus of rupture of 43.1 MPa and a thickness swelling of 1.9%.
2)There were blisters in surface strand layers of all manufactured boards when surface moisture content was 20%.
3)It was supposed that the carbon dioxide generated by the reaction of EMDI and water influences blisters and physical properties.

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Various kinds of modified cooking methods have been used in many kraft pulp mills to improve properties of pulp from wood. Furthermore, anthraquinone compounds have been used as cooking additives to improve both delignification and pulp yield. This paper discusses the way to apply 1,4-dihydro-9,10-dihydroxy-anthracene sodium salt (SAQ), one of the anthraquinone compounds, to the recent modified cooking processes. In order to investigate the conditions of modified cooking, we developed laboratory cooking equipment that can reproduce the cooking by a mill-digester. The equipment has a small autoclave in which part of the cooking liquor can be added separately.
Using the equipment, kappa numbers of hardwood kraft pulp could be decreased by exchanging part of black liquor with fresh white liquor at the middle of cooking process. When the entire amount of SAQ was added at the beginning of cooking, the pulp yield at a given kappa number was more efficiently improved than when it was separately added at the beginning and the middle, the effect of SAQ, meaning the improvement of the pulp yield, was as good or better under the various alkali-concentrations than when the entire amount of white liquor was added at the beginning of cooking. The amount of the anthraquinone compound in black liquor extracted at the middle of cooking was only less than 5% of the total charge.

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In order to define the effects of thermal expansion and thermal decomposition on the destabilization of quenched wood, we measured the stress relaxation of steam-treated wood and oven-dried wood under control and quenching conditions, respectively. The degree of destabilization was evaluated by the fluidity (1-E_t/E₀) and its increase in relation to the control wood. The fluidity (1-E_t/E₀) of oven-dried wood clearly did not change after quenching. This meant that the reason for destabilization was not closely related with the thermal expansion of components. For steam-treated wood preheated below 120°C, the destabilization of the quenched sample was of the same degree as the control sample and was not related to the preheating time ; however, when the preheating temperature was over 120°C, the degree of destabilization for the quenched sample was reduced with increasing preheating time. At the same time, for steam-treated wood preheated over 120°C, the change in lignin content was slight while the holocellulose content was greatly reduced, so it was inferred that destabilization had a close relationship with the holocellulose content. Moreover, it was indicated that changes in the hygroscopicity of wood due to holocellulose reduction affected destabilization.

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We investigated the influence of external log quality on the presence of knots on the sawn faces through the sawing tests of medium diameter, normal quality sugi (Cryptomeria japonica D. Don) log.
When the log surface was divided into four log faces, the results showed a tendency for an increase in the appearance rate of clear sawn faces as the distance from the log face to the pith on the top end of the log increased. Except butt logs, the results also showed a tendency for an increase in the appearance rate of clear sawn faces as the distance from the log face to the pith on the butt end of the log increased. A proportionality was not seen between the distance from the log face to the position of maximum warp and the appearance rate of clear sawn faces. The appearance rate of clear sawn faces on the opening face with the sawing method whose opening face was decided by the most distant log face from the pith on the top end was about 10% higher than that with the conventional sawing method whose opening face was decided by the warp of the log.
Therefore, it was thought that the pith on the top end was the most effective index to predict the log face in which a clear sawn face was expected.

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