Traditional Knowledge of Plant Dyeing, Sustainable Practices and Potential for Improved Techniques by Monpa in Tibet, China

BackgroundNatural dyes used since historic times for coloring food, leather, textile fibers, and paint body parts. The use of natural dyes has suffered drastically under the influence of modern technologies in the textile industry and socio-economic changes. Hence, ethnobotanical studies of indigenous dye plants and dyeing craft in local communities are urged to protect their potential ecological and economic value. MethodsWe conducted semi-structured surveys on dye plants and traditional craft in 11 Monpa villages of Mêdog County, South-east Tibet, China. The cultural significance of local dye plants was evaluated by an index of cultural importance (CI). Field research was conducted to record the indigenous madder (the root of Rubia wallichiana Decne.) dyeing craft. An experiment was performed with aqueous extract and ethyl alcohol extract of residue remained after water extraction. These two dye solutions were respectively used to dye two fabrics with two biomordants and two metallic mordants by three mordanting methods. We evaluated color properties that were characterized by physicochemical evaluations using UV-visible spectroscopy and FTIR analysis. The dyed fabrics were evaluated by indicators of color strength and fastness including washing, rubbing, and perspiration. ResultsAltogether 15 species belong to 12 families were listed as dye plants, which were used in cloth and food dyeing. The CI of R. wallichiana was highest. Monpa ethnic group used madder directly or with metallic mordants. It was found experimentally that biomordants and metallic mordants were comparable in improving the dyeing properties of indigenous madder. The dyeing properties of both extracts of madder were equal or ethyl alcohol extraction was marginally better.ConclusionsUse of dye plants and indigenous knowledge of dyeing still present in the Monpa ethnic group. Our experiment revealed the feasibility of enhancing the dyeing property and reuse of the residue from madder dyeing. The improved dyeing and reuse of residue can improve the ecological and economic benefits of local meanwhile provide basic application research for the subsequent commercialization of plant dyes.