Protection and fastness of green color of moso bamboo (Phyllostachys pubescens Mazel) treated with chromium-based reagents

The attractive green color of moso bamboo (Phyllostachys pubescens Mazel) culms fades without chemical treatment. Chromated copper arsenate (CCA) has been used to protect the green color of bamboo, but CCA is harmful to factory workers and the environment. To overcome the toxicity of arsenic in CCA, two chromium-based formulas developed by the authors, chromated copper phosphate (CCP) and chromated phosphate (CP), were evaluated for their protection of the green color of moso bamboo. The results revealed that bamboo treated with CP had a greener color than those treated with CCA or CCP. The concentration, treatment time, and CrO₃/H₃PO₄ ratio in CP solution greatly affected the color of moso bamboo culms. The attractive green color, which resembles the color of fresh-cut moso bamboo, was obtained by treating bamboo with 2% CP solution at 60°C for 3h, using a 11 CrO₃/H₃PO₄ ratio in aqueous solution. In addition, the CP-treated moso bamboo exhibited excellent green color fastness in both accelerated ultraviolet lightfastness testing and outdoor weathering exposure.