Gerald Koch

Wood and its processing into particles are, combined, the largest cost factor in the production of particleboard, followed by the cost of adhesive. Thus, reducing their cost is a goal of process optimization. This study investigated whether possible savings could be identified and quantified by determining the particle surface using automated three-dimensional laser-scanning technology (3D Particleview, Fagus-Grecon). The focus was on saving adhesive by sieving out adhesive-consuming fines. It was shown that, currently, with the actual prices for wood (89 €/t), particle preparation (37 €/t), and adhesive (570 €/t), the resulting additional costs for particles are overcompensated by the savings for adhesive with high adhesive content (e.g., 19%). The assumption of uniform distribution of adhesive on the total surface of all particles was checked for correctness using digital reflected light microscopy (VHX-5000, Keyence). Since urea-formaldehyde (UF) adhesive commonly used in particleboard production can only be detected with increased effort, phenol-formaldehyde (PF) adhesive was applied for the tests. Ultraviolet microspectrophotometry (UMSP) was used to rule out excessive penetration of the adhesive into the wooden tissue of the particles. The examination of the distribution of the adhesive over the surface showed that smaller particle sizes tended to be more heavily coated with adhesive. This means that the calculated savings still underestimate the real-life potential or that potential savings exist even with lower adhesive prices or higher prices for wood.

Persian oak (Quercus brantii Lindl.) is a valuable native species in Iranian forests with very limited availability of data on its wood properties. The objective of the current study was to determine the influence of altitude and slope on physical properties and fiber dimensions of Persian oak wood. In addition, the relationship among wood properties, site conditions (temperature and rainfall) and growth traits of trees (tree height, DBH, basal area, age, crown diameter, crown basal area, volume and annual diameter increment) were studied by principal component analysis (PCA). Three altitude levels (1730, 1980 and 2250 m) and three slope classes (45%) were considered in the current study. It was determined that trees growing in the intermediate altitude (1980 m) showed the highest oven-dry density values, and those in the lowest altitude (1730 m) revealed the lowest ones. The results also indicate significant statistical differences between altitude levels and slope classes on the fiber length, fiber diameter and volumetric swelling at the 99% confidence interval while no significant differences were found between average values of oven-dry density among different altitudes and slopes. PCA analysis indicated that altitude and temperature are the most important factors affecting the wood properties. Knowledge of the relationship between wood properties and environmental factors are essential in terms of both forestry management and wood applications.

Archaeological wood of 13 excavated oak piles from five historical bridge generations in Bavaria, dated from 1447 to 1787, was investigated by means of light microscopy (LM) and cellular UV-microspectrophotometry (UMSP) to study the ageing and natural resistance of the excavated wood. Furthermore, the mineral content of the ancient wood was determined to evaluate the impact of mineral inclusions on microbial resistance, tested using a mini block fungal test. The LM and UMSP analyses revealed well preserved cell wall structures and no significant modification of the lignin composition and distribution in predominant parts of the piles. Slight microbial decay caused by soft rot and erosion bacteria was only detectable at the outermost millimetres of individual piles. The fungal mini block tests yielded mass losses of ancient oak samples between 15% and 30%, independent of their analysed mineral content. The results provided evidence that the fungal resistance of the investigated ancient wood is mainly determined from the special soil with its high mineral content.