Quercus robur wood veneer with pronounced natural color uniformity and stability by regulating the content of phenolic extractives

Abstract

Wood is recognized as a promising raw material for house furnishings due to its good mechanical properties, relatively low density and weight and biodegradability. However, the natural color difference of wood veneer always induces value degradation. Therefore, accurate color regulation plays a pivotal role in producing high-value wood-based composites. In this study, a Quercus robur wood exhibiting a pronounced color variation was treated by an alkaline hydrogen peroxide (H2O2) homogenization process to regulate the content of phenolic extractives, and ferric chloride (FeCl3)-induced color modification to optimize the color. In order to minimize the chromatic disparity of the veneer, it simultaneously restores its initial hue and thus enhances its value. The color difference values of natural untreated Quercus robur veneer and homogenized toned veneer were assessed by using color testing based on the CIEL*a*b* 1976 system. The results demonstrated that the levels of lignin, hemicelluloses, and extractives in the toned veneers subjected to homogenization pretreatment exhibited varying degrees of reduction, along with a decrease in their affinity for iron ions. By assessing the colorfastness of homogenized, toned veneer through testing, the water and light resistance of the homogenized pretreated veneer is significantly superior to that of Quercus robur treated exclusively with iron salts. A higher level of color uniformity in the homogenized pretreated toned veneers, with the toned veneers treated with 0.16 mol/L iron salt exhibiting the closest resemblance to natural Quercus robur wood. This study not only reveals a novel methodology for chemically modifying the hue of wooden surfaces to achieve natural color uniformity but also presents a sustainable and facile approach to promote the high value-added utilization of wood.