Is Tencel an Environmentally Friendly Alternative to Bamboo Fabric?

Photosource: http://www.passengerpigeon.ca

There’s never only one side to any story. Bamboo fabric is a classic example of a product that on the surface sounds very green. Bamboo plants grow incredibly quickly, can be planted in areas unsuitable for other crops, and rarely need any pesticides or herbicides. But issues arise with the way the fibres are processed and the fabric manufactured.

The most popular manufacturing process involves sodium hydroxide and carbon disulfide, both highly toxic chemicals to humans, and when released into the environment. The majority of bamboo fabric production takes place in China, a country not renowned for worker’s rights or environmental respect.

Bamboo fabric may have something to learn from another material that’s been produced quietly, with little environmental fanfare, for the last twenty years. Lyocell, sold as Tencel, is a fabric made from wood pulp. Tencel and Tencel blends drape well and are used predominantly in dresses and formalwear.

Tencel is manufactured in a proprietary process by the Lenzing Group, a international group of companies based in Austria. Lenzing describe themselves as “committed to the principles of sustainable management and very high environmental standards.” Tencel is manufactured in a similar way to bamboo fabric, but with important differences that may be the solution to green bamboo fabric manufacturing.

Here’s the recipe. First, take some wood pulp. Lenzing’s pulp mill uses hardwood – mostly birch and oak – from sustainable forestry plantations. The trees are chemically pulped and bleached. Lenzing say they utilise a closed-loop process and don’t use chlorine bleach to minimize environmental impact. However, Lenzing also buys wood pulp and their website becomes vague as to what conditions their suppliers’ wood pulp is manufactured under.

Next, the wood pulp is turned into fibres through a process called “solvent spinning”. Wood pulp is dissolved in a chemical called N-Methylmorpholine N-oxide (NMNO). The liquid is squirted through thousands of tiny holes in a spinneret, forming individual Tencel fibers. The spun fibres are washed, the NMNO is retrieved from the water, and it is purified, and reused in a 99% closed-loop process. NMNO can be toxic, but much less so than the sodium hydroxide and carbon disulfide used for processing bamboo. Small quantities of NMMO are actually produced in the body as a metabolite of several common drugs.

With a sustainable source of wood pulp, Tencel manufacturing has a much lower environmental impact than bamboo fabric. But despite considerate forestry practices, tree farms are more damaging to the ecosystem than growing bamboo. When natural forests are cleared for farms the local ecosystem suffers from the reduction in bio-diversity in the area. Bamboo is the slight winner here: it naturally colonises areas other plants find challenging and often grows with few other species for company, so it has less environmental impact when planted as a monocrop on a farm. Bamboo also grows much faster than hardwood trees, processing many times more CO2 from the environment than trees can.

Bamboo can be grown ecologically, and because of the increasing popularity of bamboo, companies are developing new, greener, ways to process the fibres ecologically, inspired by Tencel processing. Companies like Pure Bamboo are using new closed-loop processing methods, and hopefully more will follow.

Tencel is currently more eco-friendly to manufacture, and – depending on your standards – acceptably eco-friendly to grow. But bamboo fabric has the potential to be a true eco-friendly cloth.

For more on Tencel, What is Tencel on Wisegeek.

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This post was written by one of Green Cotton’s contributing writer’s Brit.

Bamboo Processing Considerations II

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By Shana

The advantage of many renewable fibers such as bamboo is that they can be grown without petroleum based toxic pesticides, herbicides and defoliates such as those that are typically used in cotton growing.

Despite the nearly impeccable growing characteristics of bamboo, there are some concerns associated with its processing (as noted in my recent post Bamboo Processing Considerations I). Since that post, I have come across evidence suggesting that there are companies currently processing bamboo in a low impact manner.

At Green Festivals in DC, I visited Jonano, one of the best eco-fashion apparel stores in my view, and spoke with Bonnie Seifers (owner and designer of the company). According to Bonnie, it is possible to process bamboo without harsh chemicals and damaging environmental impacts. Her process (obviously proprietary) does not use bleaching and is apparently organic. Jonano carries a range of organic clothes for men, women and children with a fashionable, yet comfortable look. Many of her fabrics derived from bamboo and processed into her own proprietary blend called ecoKashmere.

Further to the green bamboo processing argument, last weekend I had the opportunity to visit Envi, a relatively new eco-friendly clothing store on Newbury Street in Boston, MA. Envi carries a broad range of green apparel labels from Stuart + Brown, to Panda Snack, Twice Shy and Toggle as well as Edun.

While small, the store carries a variety of styles including some of the softest, most appealing bamboo shirts and skirts I have seen. In chatting with the salesperson, I learned that at least some of the companies producing bamboo clothing are borrowing from the practices of Tencel production and reusing the solvents throughout the pulverizing and combing process, such that environmental damage is minimized. So it may be the case that the bamboo clothes (at least those in Envi Be Green and by Jonano) are more green than originally thought.

While it is very difficult to get a solid handle on exact bamboo processing steps and components, Tencel production appears to be one of closest comparison. Tencel is similar to bamboo in a number of respects.

Tencel is the brand name for a fiber generically called lyocell, and lyocell is a man-made fiber from natural wood pulp. It has proven popular in clothing primarily because it is absorbant , soft and comfortable. It is particularly appealing in high humidity climates. Lyocell (or tencel) is stronger that cotton and rayon and does not lose strength when wet. It is frequently blended with cotton or polyester, typically in oven fabrics. It is manufactured using a solvent spinning process, but the solvent is reused so that there is little environmental exposure.

Patagonia, a remarkably innovative outdoor clothing company with one of the most pioneering green track records of the last two decades has been using tencel for quite some time. According to Kill Vlahos, environmental analysis director for Patagonia, “Tencel production is a closed loop system. All solvents remaining after processing are reused; none gone into the waste steam. Most processors won’t talk about bamboo processing. They say it’s a proprietary process. We need disclosure, and the information we get has to reveal true environmental advantages for us to consider the fiber.” Source: ‘All Natural” in http://www.geartrends.com Winter 2005

So if this is also the case for Bamboo, then we are looking at a much more eco-friendly product. However I dare say that not all companies are embracing the closed loop production process (without multi-stage bleaching). At Green Festivals, I asked as many vendors as possible who were selling bamboo fabrics/products, and only one of them, Jonano confirmed organic, eco-friendly processing. Others, such as Pure Fiber, mentioned that they do not have full information on the processing, since it is proprietary and done before they get the fabric (in places such as Pakistan).

Hopefully someday we will have a better certification process available that will also include the processing of these fibers. Until that time however, it is important to ask questions on the sourcing of materials and make sure that the processing meets your own standards of green-ness.

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Source: Flickr (Ewe Give Me Knits!)

Top photo source: Flickr (spiffxp)

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