In order to understand the physical and chemical properties of specific pieces of lumber, it is essential to identify the type of tree it has come from. The most common way of doing this is by microscopic observation. In Japan, the study of wood anatomy has a history of 130 years. Over that period of time, the database of wood anatomical characteristics has grown, and it is now possible to identify wood from almost every type of tree harvested in Japan. However, with this kind of anatomical observation alone, it is often difficult to make positive identification down to the species level. For this reason, other techniques such as those using molecular DNA or chemical analyses are applied. Furthermore, for identifying the wood species of historically valuable wooden artifacts, non-invasive methods are more desirable. This report reviews the current identification methods as well as the ongoing research for identification technologies suited to the needs of contemporary society for combatting illegal logging, the promotion of wood self-sufficiency, and so on.

It is believed that acoustic quality and stability of wood are improved during long term ageing. However, it has recently been suggested that a part of those ageing effects are recovered by moistening at high humidity. Similar temporary effects have been recognized when wood is heated at high temperatures in the presence of moisture. Those temporary changes are speculated to be due to the physical ageing of amorphous wood polymers involving the temporary closure of micropores in the wood cell wall. For appropriate conservation of old wooden musical instruments and cultural properties, the recovery of physical properties due to moistening in humid condition should be taken into consideration. In addition, the temporary effect of heating should be eliminated for precise evaluation of the practical performances of heat-treated wood. This paper describes the reversible and irreversible changes in wood properties relevant to the practical quality of wooden crafts and musical instruments due to natural ageing and heat treatment.

Hichiriki is a traditional Japanese oboe used for Japanese ancient court music (Gagaku). The vibrating plate (Rozetsu) of the hichiriki is made from a reed (Phragmites australis), and the best reed is believed to be harvested in the Udono area along the Yodogawa river. In this study, we observed the anatomical structure of reeds selected by experts, and measured their density and transverse compressive strength to clarify the basic requirements for quality instruments. Within an internode, the upper part was always thinner and denser than the lower part, depending on the thickness of the low-density parenchyma layer beneath the cortex. Selected reed was slightly thicker and denser than unselected reed, but those differences were not significant. On the other hand, the transverse compressive strength of selected reed was significantly greater than that of unselected reed, and the upper part showed the highest strength. It is considered that sufficient transverse strength is required while the thinner, i.e. deformable upper part is preferred, because an end of the reed culm is compressed to form the closed end of the double-reed. With respect to shape, density and compressive strength, the Mukaijima area along the Uji river is a potential field to harvest reeds for hichiriki.

Color changes of wood during natural aging are important from the aesthetical point of view and as criteria of degradation. The color properties of aged keyaki wood samples were compared with those of recent wood samples and those of heat treated wood samples in the previous paper. The values of L^* and b^* of aged wood were lower than those of recent wood, which was similar to those of heat treated wood. The values of a^* of aged wood were larger than those of recent wood and heat treated wood, showing a different trend compared to heat treated wood. The results of kinetic analysis showed that the color changes during natural aging occurred more rapidly than the prediction estimated from the color changes of heat treated wood. These results were different from those of hinoki wood, which suggested that the responses to natural aging would differ depending on wood species.

This study aims to evaluate the effect of basic design attributes included in wooden wall panels on humans by Eye Fixation Related Potentials (EFRPs) as physiological responses, by eye tracking, and by sensory evaluation. As visual stimuli, six wooden wall panel images were prepared, which contained different visual features such as knots, the direction of timber elements, and staggered-joints. These visual stimuli were displayed in their actual size (1016 mm×576 mm) on a large monitor, and 28 subjects freely observed each image for two minutes. During observations, the subjects' EFRPs from their occipital region and their eye movements were recorded continuously by an electroencephalograph and an eye tracker, respectively. In addition, sensory evaluation was conducted for each image after the free observation. In the sensory evaluation, there were significant differences in “preference” and “homogeneity” scores between knotty and flat wall images. EFRPs were affected by the arrangement of wooden elements rather than by knots in the wall panel images. Accumulated time or frequency of eye fixation revealed high visual inducement by knots.

Wood has unique reflection properties originating in its anatomical structure. Gloss transition is a typical one of such properties, which appears by changes in the optical geometry of the timber surface, the lighting source, and the observer. Wavy grain or curly grain easily tend to show the gloss transition, and this special appearance directly affects the aesthetic value of various wood products and craftworks. Thus, curly maple has been used as backboards of the violin with fiddleback figures. To elucidate the relationship between the appearance and the attractiveness of the fiddleback figures, image characteristics related to the gloss transition were calculated regarding 10 violin backs, and psychological response and eye movements of observers viewing videos of the gloss transition were measured. Results were summarized as follows: 1) Contrast spectra derived by the image analysis demonstrate the gloss transition effectively. 2) Subjects' eyes follow the gloss transition, although distribution patterns of eye fixations are different for each fiddleback figure. 3) The fiddleback figures of higher contrast tend to evoke a more “Varied” impression on observers.

Wood has a highly aesthetic appearance. There have been some efforts to elucidate its psychological and/or physiological effects on humans, but quantitative data are still insufficient. This study aimed to examine the effect of contrast change in grain patterns on visual attractiveness and impressions. Three species and ten coating specifications were selected and thirty kinds of fancy veneer overlaid plywood were prepared. Their surface images were captured by the imaging spectroscope system, and were subjected to histogram analysis and multi-resolution contrast analysis to derive contrast values as image characteristics. The specimens were also provided for free observation and sensory evaluation by 27 subjects. During the observation, eye fixations of the subjects were recorded by an eye tracker. The contrast values derived from the image analyses exactly expressed the appearance change by coatings, and showed highly positive correlation to “subjective noticeability of grain patterns.” Moreover, the eye tracking revealed that the visual attractiveness of the specimens was affected by the contrast changes.

For the purpose of evaluating visual preferences for 50 Japanese wood species, the interval scale value of visual preferences by subjects whose age ranges from 19 to 30 years was determined by using a paired comparison method. Correlation analysis between the color attributes of each wood image and the interval scale values of preference showed that the preference had a strong positive correlation with the “coefficient of variation of R values in the RGB” and the “minimum value of R-value”, and a strong negative correlation with the “coefficient of variation of R value”. These results suggest that wood species which have strong redness with warm colors and wood grain that is not clear are visually preferred.

This study investigated the visual influence of wood used in workplace interiors through a quantitative analysis of textual data obtained by interviews using photographs of workplace interiors. Twenty photographs of workplace interiors were presented to each participant, who was requested to divide them into groups on the basis of similar impressions. Subsequently, the participant was asked his or her impression of the companies in each group and the reason for such an impression. Nonmetric multidimensional scaling analysis was conducted on the grouped photographs and corresponding answers. Although the participants had not been informed that the photographs were of “wood interiors” and “non-wood interiors,” the photographs were divided into “wood interior” and “non-wood interior” ones in two-dimensional space, and also the “wood interior” ones were placed around the word “wood.” The words “warm,” “comfortable,” “calm,” “bright” and “friendly,” which are related to a good workplace environment and good impressions of companies and workers, were also placed around the word “wood.” This suggested that wood used in workplace interiors would have a favorable effect on the people there.

A numerical model of indoor air concentration, which was calculated from the mass balance of the testing room and time-emission-factor relationships obtained by the small chamber method, was studied. To predict concentrations in environments with different loading factors, the relationship between acetaldehyde concentration and loading factors was also studied. Acetaldehyde emissions from plywood, particleboard, and MDF (medium density fiberboard) were measured using the 20-L small chamber method with several loading factors. Emission factors of wood-based interior materials such as plywood, LVL (laminated veneer lumber), composite flooring, and wallpaper-covered plywood were measured in both small chambers and a full-scale testing room. Under a constant ventilation rate, acetaldehyde concentration was proportional to loading factors but emission factors were independent of loading factors. The acetaldehyde concentration model for the testing room was based on parameters acquired from the small chamber measurements. Predicted values were in accordance with measured values in the testing room.