Novel environmentally-benign methods for green-colour protection of bamboo culms and leaves

The objective of this study was to search for appropriate environmental-benign preservatives as green-colour protectors for the culms and leaves of ma bamboo (Dendrocalamus latiflorus), moso bamboo (Phyllostachys pubescens) and makino bamboo (Phyllostachys makinoi). Five water-borne copper-based preservatives, namely ammoniacal copper quaternary compound-type B (ACQ-B), copper azole-type A (CBA-A), copper azole-type B (CA-B), tanalith CY (TCY) and micronized copper quaternary (MCQ), were tested as green-colour protectors. Results revealed that excellent green-colour protection (a* values of −13.2, −7.6 and −6.3, respectively) was obtained when the culms and leaves of ma bamboo, moso bamboo and makino bamboo culms were treated with 0.25% aqueous TCY solution in a 100 °C water bath for 2 h. Furthermore, to evaluate the effects of 0.25% TCY treatment on the green-colour fastness of bamboo culms, two exposure tests including indoor exposure and outdoor weathering were employed in this study. Results from the 6-month exposure tests in both indoor and outdoor environment demonstrated that specimens treated with 0.25% TCY exhibited good colourfastness. To improve the treatment efficacy in bamboo culms, both atmospheric pressure impregnation and vacuum pressure impregnation were used. The results indicated that green-colour protection could be obtained by the two impregnation treatments in 0.25% TCY solution.