Bamboo fiber is made from bamboo timber that is at least four years old. When new shoots reach their full height, they are marked with a year code to ensure they are harvested at the correct maturity. After harvesting, the shoots are taken to the mill, crushed and submersed in a strong solution of sodium hydroxide to dissolve the bamboo cellulose. Then carbon disulfide is added to regenerate the fibers which are then removed, washed and bleached. The fibers, which are very long in staple and finer than other fibers, are then spun into yarn like any other fiber.
The longer staple and higher strength makes it a tough, yet soft, yarn. It is not as susceptible to wearing and fraying as many other natural yarns, giving the garment excellent durability and longevity. The hollowness of the fiber creates a very high level of absorbency, allowing it to hold dyes and pigments more readily and permanently.
Bamboo yarns, by the strictest definition, are not natural since the bamboo is chemically processed in order to turn it into yarn. The process is actually similar to the process of making soap, where strong solutions of sodium hydroxide are used to change fat into soap. The other chemical used is carbon disulfide, an organic solvent that evaporates very quickly. In large concentrations it is a toxin. However, because it evaporates so quickly, it does not remain in the fibers. It also breaks down once released, in a few days, to simpler carbon and sulfur compounds which are all around us in daily life. We include bamboo yarn in our list of natural choices because, although processed, the end product is very clean, non-toxic and actually very eco-friendly and biodegradable. Unlike synthetic yarns or fabrics, bamboo fibers will decompose in soil in a short time.
Pure bamboo is softer than cotton and has a texture similar to a combination of cashmere and silk. The cross-section of the fiber is filled with various microscopic gaps and holes, giving it excellent moisture absorption and ventilation. It’s moisture absorbency is double that of cotton which means it will evaporate human sweat very quickly, making people feel extremely cool and comfortable, even in summer. Additionally, it releases dirt and stains much more easily than cotton.
Bamboo fibers contain natural antibacterial agents. The Japanese scientists that discovered this agent named it ‘bamboo kun’. This natural antibacterial property helps keep bamboo garments from picking up odors that result from bacterial action.
Another useful property of pure bamboo fiber is its elasticity of almost 20%, providing a natural replacement for the rubberized or synthetic stretching additives in modern yarns.