A clean and novel drying method for bamboo colorization and in-situ surface wax utilization

Abstract

Round bamboo is considered an environmentally friendly product, with surface color crucial to its value. Surface wax is crucial for the growth and development of bamboo, but can alter the color of round bamboo and easily detach under the influence of heat and humidity, leading to uneven colorization. By controlling the drying temperature at 90 ℃, the surface wax can be uniformly levelled on the bamboo’s surface, enhancing its color to a consistent deep red. Chromaticity measurements show L* values between 29.58 and 34.68 and a* values from 5.58 to 6.04 at 90 ℃. DSC test shows that the wax completely melted and levelled evenly at 90 ℃, solidifying uniformly on the bamboo surface upon drying, thus realising in-situ utilization of the wax. FTIR, GC-MS and XPS analyses reveal that drying at 90 ℃ leads to an increase in chromogenic substances within the wax and bamboo green, along with heightened intensity of unsaturated functional groups, and deepening of surface color, ultimately achieving the colorization of the round bamboo. Furthermore, the prepared round bamboo exhibits excellent pencil hardness (5 H), adhesion, and glossiness (5.38 GU), while maintaining its mechanical properties. This innovative method integrates drying, colorization, and wax utilization in one step, offering a novel strategy for enhancing round bamboo’s quality.