Effect of sand blasting treatment on green colour preservation and surface characteristics of Moso bamboo culms

Green colour preservation of bamboo surface is an efficient approach to improve the aesthetic and economic values of bamboo. Previous research on bamboo green colour preservation used large amounts of chemicals, which limited its practical production. In this study, sand blasting was used as a pretreatment method during the green colour preservation process. The results revealed that the application of sand blasting treatment could avoid the use of surfactant. With the same potassium hydroxide concentration, bamboo samples treated with sand blasting exhibited greener colour as indicated by lower a* value. This was because sand blasting treatment could almost completely remove the wax, which improved the permeability of chemicals for subsequent treatment. The optimized conditions for green colour preservation of bamboo were sand blasting treatment followed by 3% KOH treatment (40 min) and 1% copper sulfate treatment (1.5 h). The UV light resistance test result indicated the green colour of the bamboo surface could be retained even after 300 h of irradiation. The analysis of the bamboo surface characteristics revealed that the green colour preserved bamboo surface had similar surface characteristics to that of the original bamboo in terms of both the green colour, hydrophobicity, and surface topography.