WOOD RESEARCH Volume 68, Number 4, 2023
Ceyhun Kiliç, Sibel Yildiz, Ayşenur Gürgen, and Derya Ustaömer

Effects of Different Climate Types on Color Change of Wood Material used Outdoor

Field tests are important for evaluating how wood performs in real-world conditions and making informed choices for material selection. These tests help assess wood’s durability, strength, decay processes, and resistance against harmful organisms. Furthermore, it helps users make more informed decisions about the color of wood and understand the importance of color changes depending on the place and time of use. Because weather conditions are a significant factor that influences the color of wood. Wood that is exposed to prolonged sunlight, moisture, and rain may experience fading, darkening, or staining in its color. In this study, heartwood, sapwood, and CCB impregnated sapwood samples of Scotch pine, spruce, beech and alder were exposed to the soil contact (hazard class 4) according to EN 252 for 3 years in Trabzon, Muğla, Çanakkale, and Elazığ provinces of Turkey with completely different climatic conditions from each other. Color parameters and color change values were evaluated using L*, a*, b* and ΔE* of the samples collected from test sites. The most significant color change was observed at Scotch pine in Çanakkale province. Greater color changes were observed in the heartwood of coniferous species. Impregnated samples showed the least color change.

WOOD RESEARCH Volume 67, Number 4, 2022
Sefa Durmaz and Özlem Özgenç

The changes in the surface of flat pressed wood-plastic composites exposed to artificial weathering

In this study, the wood flour content’s effect on the weathering performance of flat pressed WPC was investigated. The high density polyethylene was reinforced with four different wood flour content (10%, 30%, 50%, 70%). The weathering performance of WPC was determined by the 400 h of artificial weathering test. According to the results, the color change is inevitable as long as the wood flour is used as filler. Surprisingly, the highest color change was obtained from WPC containing 30% WF, contrary to 70% of wood flour. Similarly, the whiteness of the surface of WPC increased with exposure time. The photooxidation resulted in the chain scission and shorter molecules, which were observed by ATR-FTIR analysis. The changes in the intensity of characteristic polymer (2914 cm-1 and 2846 cm-1) and wood peaks (1510 cm-1 and 1027 cm-1) exhibited the photodegradation on WPCs’ surface, which resulted in color change. Moreover, the light microscopy investigation showed surface degradation. The extensive weathering conditions caused surface cracks and surface roughness. The visual appearance of WPCs also demonstrated how to change the surface character of WPC during the 400 h of artificial weathering. In conclusion, the increase in the wood content increased the intensity of degradation.

WOOD RESEARCH Volume 66, Number 1, 2021
Xin You Liu, Xin Wei Tu, and Mihaela Liu

Effects of light thermal treatments on the color, hygroscopity and dimensional stability of wood

Ailanthus wood (Ailanthus desf.) was thermally treated at three different low temperatures (140, 160, 180°C) for 2 and 4 h in order to investigate the effects on wood color, hygroscopity and dimensional stability. Results indicate that mass loss increased following the treatments, while equilibrium moisture content decreased from 11.86% to 9.88% for the 180°C and 4 h treatment. Moreover, improvements in the dimension stability were observed for post-treatment samples. The thermal treatment induced color changes in the Ailanthus wood, with a significant reduction in the lightness, yet the redness and yellowness exhibited minimal changes. FITR spectra of the thermally treated wood suggest that the heat treatment resulted in the deacetylation of hemicellulose. These results help to conclude that thermal treating temperature under 160°C can improve wood dimensional stability and maintain original color.