The Colour of Tropical Woods Influenced by Brown Rot

• Main Authors: Zuzana Vidholdová, Ladislav Reinprecht
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Forests
• Subjects: tropical woods; brown rot; <i>Coniophora puteana</i>; colour; CIEL^*a^*b^* system
• Online Access: https://www.mdpi.com/1999-4907/10/4/322

Interesting aesthetic properties of tropical woods, like surface texture and colour, are rarely impaired due to weathering, rotting and other degradation processes. This study analyses the colour of 21 tropical woods before and after six weeks of intentional attack by the brown-rot fungus <i>Coniophora puteana</i>. The CIEL^*a^*b^* colour system was applied for measuring the lightness, redness and yellowness, and from these parameters the hue tone angle and colour saturation were calculated. Lighter tropical woods tended to appear a less red and a more yellow, and had a greater hue tone angle. However, for the original woods was not found dependence between the lightness and colour saturation. Tropical woods at attack by <i>C. puteana</i> lost a weight from 0.08% to 6.48%. The lightest and moderately light species&#8212;like okoum&#233;, iroko, ovengol and sapelli&#8212;significantly darkened, while the darkest species&#8212;weng&#233; and ip&#233;&#8212;significantly lightened. The majority of tropical woods obtained a brighter shade of yellow, typically weng&#233;, okoum&#233; and blue gum, while some of them also a brighter shade of green, typically sapelli, padouk and macaranduba. <i>C. puteana</i> specifically affected the hue tone angle and colour saturation of tested tropical woods, but without an apparent changing the tendency of these colour parameters to lightness. The total colour difference of tested tropical woods significantly increased in connection with changes of their lightness (&#916;<i>E^*_ab</i> = 5.92 &#8722; 0.50&#183;&#916;<i>L^*</i>; <i>R</i>² = 0.37), but it was not influenced by the red and yellow tint changes, and weight losses.