Bamboo rayon is marketed as an eco friendly fibre. It's water efficient, it rapidly regenerates, and it's a carbon neutral fibre. That is, it is a plant-based fibre that absorbs the same amount of carbon dioxide from the atmosphere as it releases during harvesting.
But, as I was pounding a 20 litre bucket of sauerkraut with my trusty bashing stick chopped from a small bamboo thicket on my property, it got me thinking: how on earth does this huge plant, known for its strength, sturdiness and ability to survive typhoons, become a durable and yet soft and luxurious fibre for use in bedding, clothing and underwear?
The answer may be not so eco-friendly.
I picked up a copy of Sustainable Fashion and Textiles
by Kate Fletcher and found that most bamboo fabric is a bamboo rayon, which is a man made fibre made from cellulose using the viscose process. It's this processing into a viscose or rayon material where eco-fashion campaigners go a little quiet.
The process of producing bamboo rayon is much like any other viscose rayon fabric. It Kate's book, she summarises the process into first purifying and bleaching before soaking in sodium hydroxide. It's then treated with carbon disulphide and spun in a solution of sulphuric acid, sodium sulphate, zinc sulphate and glucose. Yikes! With significant emissions to air and water, no wonder the processing of viscose places it in the category of a high impact fabric.
Kate even cites a study in her book that concludes, "The toxicity of viscose water effluents had high levels of bio-chemically degradable substances, organic matter, nitrates, phosphates, iron, zinc, oil and grease. The effluent was completely devoid of dissolved oxygen and micro organisms."
So while bamboo may be a thoroughly sustainable raw product, processing that into a fabric for clothing involves chemically dissolving natural polymers in order to extrude a continuous filament with desirable qualities for practical material use.
It's heartening to know though that, since this book was published in 2008 there have been advancements in the processing of bamboo fibre. Factories are working towards producing bamboo material in a similar fashion to lyocell, made from wood pulp and dissolved using a non-toxic solvent producing non-hazardous effluent. With almost all organic compound being recycled and renewed, as well as full biodegradability after 6 weeks in an aerated compost heap, one of the very few challenges with lyocell is reducing the energy consumption to produce it. There are already companies such as Five Bamboo
that are using the lyocell process to produce their bamboo fibre.
The general rule of thumb is that companies who practice green methods are pretty proud of it, and will announce it to their customers. This makes supporting green companies much easier, if you know what to look for.
- Choose bamboo which has been Oeko-Tex certified, meaning the fabrics have been tested to be safe for human use. Note that Oeko Tex 100 does not mean that no chemicals were used in the processing of this bamboo material, but that no chemicals were detected in the final product.
- Choose bamboo viscose from factories with strict effluent treatment protocols. The concern with bamboo viscose is not that the chemical residue remains on the bamboo material, but in the disposal of the chemical waste product.
- Choose bamboo viscose treated without chlorine-containing bleach and zinc sulphate.
- Choose companies using the lyocell process or non-toxic solvents to produce the bamboo fibre.
Bamboo linen, on the other hand, is a mechanical method whereby woody parts of the bamboo plant are extracted directly through from bamboo culms, crushing the woody part of the bamboo and using a natural enzyme to break down the walls and extract the bamboo fibre. It's still labour intensive, but produces a very strong, high quality product. And durability is one important element to sustainability in the clothing industry, which seems to have been forgotten in the hoards of fast fashion products.
The bamboo plant is without a doubt a sustainable source material. Some species can grow up to a metre in a day, sequestering more carbon than trees. Bamboo fabric, however, has a little way to go. But that doesn't mean we throw the baby out with the bathwater. The necessity of underwear at the very least means that we need to make a choice between products of a lighter shade of green and products that are not-at-all green. And a natural, organic, fast-regenerating raw material that's beginning to make great progress in its processing methods ticks quite a few boxes for me.
What's your thoughts on bamboo fabric? Share your thoughts below!
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