Consumers are being duped by misleading claims touting the environmental attributes of bamboo yarn and textiles. These products are being sold as “eco-friendly”. The premise that bamboo textiles are environmentally friendly is based on the self-sustainable nature of the plant. The following takes a closer look at the manufacturing processes used to form bamboo fiber, its characteristics, and knitting with bamboo yarn.
The Bamboo Plant
Bamboo fiber comes from the pulp of bamboo grass. It’s considered sustainable, partly because bamboo is a fast growing plant. Bamboo is self-sustaining due to its extensive root system, that doesn’t require irrigation. The bamboo plant can be grown without pesticides and fertilizers, and the farms are easily kept organic.
Although the bamboo plant is a relatively sustainable crop, the concerns are with the manufacturing processes used to produce bamboo fibers that make up yarn and textiles.
Bamboo fiber is manufactured by two different methods, either mechanically or chemically processed. The mechanical process includes crushing the stalks or the woody part of the plant, much like processing flax to form high quality linen. A mushy mass is formed, then the natural fibers are combed out and spun into yarn. The resulting strands are typically too coarse for hand knitting yarns and textiles. Mechanically producing bamboo fiber is labor intensive and expensive, so very little bamboo is made by this method.
The most common way to form bamboo fiber is with chemicals and equipment used in the same manner as in the production of rayon or viscose. Rayon is a regenerated cellulose, meaning the manufacturing of it uses “natural cellulose” from wood pulp, combined with synthetic processes to make the fibers. The “viscose process” is the most common way to form rayon, which includes the use of strong alkalies, followed by multi-phase bleaching.
The cellulose from the bamboo plant is used in place of the wood pulp to make regular rayon. Bamboo leaves and shoots are cooked in strong chemicals (sodium hydroxide), then the liquid is forced through spinnerettes (device used to extrude synthetic fibers) into more chemicals to form fine bamboo strands. These are washed and bleached to form rayon yarn, followed by dyeing. The dyed yarns are woven into fabric or made into hand knitting yarns. Manufacturers are now required to label yarns and textiles made in this way as “bamboo sourced rayon or viscose” or “rayon from bamboo”, rather than “natural bamboo”. Hence most of the clothing and yarn labelled as made from bamboo is simply rayon.
You can understand a consumer’s confusion, thinking a textile is natural bamboo, when that is far from the truth. There are now technologies that use less toxic chemicals to produce rayon from bamboo cellulose. The “lyocell process” for manufacturing Tencel, another regenerated cellulose can be modified to use bamboo cellulose.
Bamboo’s Fiber Properties
- Soft touch
- Silk-like draping quality
- Can elongate or stretch
- Has a sheen like mercerized cotton
- Highly absorbent
- Natural bamboo has antimicrobial properties, but chemical processing destroys this quality
Knitting With Bamboo
I’m not a fan of working with 100% bamboo yarn. I’ve had a couple of design disasters with it. The main problem was the extreme amount of stretching, rendering the structured garments unwearable. 100% bamboo yarn is best suited for small pieces like baby clothes, scarves, and tops. Bamboo blended yarns perform better.
I’ve had the best luck with an 80% wool and 20% bamboo blend. This blend works well for a variety of projects; the bamboo adds a beautiful sheen and the right amount of drape, and the wool provides the resiliency. The dress in the above image was designed with this percentage of wool and bamboo.
Bamboo yarn is slippery and splits easily, so you may find bamboo or other wood needles more comfortable to work with.
You should now understand that most of the bamboo used in textiles and yarn is regenerated cellulose from the bamboo plant, and chemically processed to form bamboo fiber. As an informed consumer, it is important to carefully read the fabric and yarn labels to determine the methods used to form bamboo textiles or yarn. Although bamboo is not popular in hand knitting yarns, it does have characteristics that are suitable for the right project.