Friday, July 14, 2017

That bamboo rayon may not be so green

More bad news about clothing choices came to light recently.

First, remember how I wrote that polyester shirts were greener than cotton shirts when the full use cycle is considered? Well, it turns out that polyester clothing can shed fibers in the wash, which may end up in the oceans and rivers and, eventually, in wildlife.

Rayon has been hailed as a miracle fiber.  It's silky like silk and polyester, breathes like cotton and linen, takes dye readily,  and is washable.  It used to be made from wood chips that are mill waste from making lumber out of trees.

Now that rayon has grown in popularity and the price of paper has shot up, there aren't enough trees.  Fast-growing bamboo to the rescue!  It's a grass so it grows fast.  It's renewable, natural and sustainable!

Not so fast.

When I was a chemistry undergrad at Berkeley in the 1980s, I came across a thick textbook at Moe's Books about rayon manufacturing.  The number of steps and caustic chemicals needed to turn break down wood chips into cellulose fibers and then to reconstruct them into rayon fibers is staggering.

The good news is some mills, notably in Europe and Australia, have invested in equipment to make rayon using closed-loop processes in which 99% of the chemicals are recovered and reused.  You can find them labeled with trade names such as Tencel and Lyocell.

The bad news is that most rayons on the market are dirty in the sense that they are made with great harm to the environment and workers.  Paul David Blanc wrote about this in Fake Silk: The Lethal History of Viscose Rayon.  Also read H&M, Zara and Marks & Spencer linked to polluting viscose factories in Asia.

Wastewater outfall near Sateri Fiber and Jiujiang Jinyuan Chemical Fiber viscose plants in Jiangxi, China Photograph: Changing Markets Foundation via Guardian
Just as I haven't given up eating meat entirely.  I haven't given up rayon, cotton or synthetic fibers.  I use everything in moderation and try to buy from responsible manufacturers.  I also often reuse/repurpose old textiles.



  1. Ah, life is full of choices. I choose to wear clothing made of cotton, linen, rayon, etc. Polyester is hot to wear in the SW deserts. Yes, it's a dry heat but not all polyester is manufactured for active wear, and I don't wear active wear everyday. I have sewn a little bit with bamboo knits, and have some in my stash. I think if I sew it and wear it, it's better than sewing it and throwing it away. Either way I'm doing something wrong or right?
    I like the new background on your blog. Wish I had a wall like that in my house. My books are scattered about on bookcases in different rooms. :)

    1. Thanks. I wish my bookshelves looked like that, too.

  2. Thanks for the info. I must say I find the conflicting info around about viscose a bit confusing, but it's good to know there is a way to easily tell if your fabric has been manufactured using sustainable methods. My main concern is biodegradability, and the idea polyester clothing staying in the environment forever, or worse still shedding microfibres, is a concern.

    1. Even biodegradable stuff decomposes very slowly in airless sanitary landfills, if at all.

      Plastic is petrochemical and can be incinerated to generate electricity. (As can natural fibers. E.g. cotton/rayon/linen are cellulose like wood.)

      The polyester shedding concerns me more in CO than LA because I know that LA's water recycling methods remove the fibers. Heck, it removes stuff as small as dissolved salt! OK, not all of LA's water is treated to that standard. Some of it is sent out to sea and might contain fibers. Other water is sent to farms and landscaping/parks and might also contain fibers.

      CO waste water treatment is not so advanced. CO hasn't had to invest in sewage treatment to the same extent b/c they have enough freshwater from the mountains. They minimally treat it (to low legal standards) and then send it to downstream states to deal with.

      That is why I support higher legal standards. Do you agree that one should send their downstream neighbors at least as high quality water as their upstream neighbor sent? The golden rule for water?

    2. I'm ignorant of US water politics as I'm from Australia. It is excellent to hear that LA recycles its wastewater as it's been a political football here for so long. From what you write it seems there definitely needs to be a tightening of legal standards regarding the treatment of water which are standardised across states.

      I honestly did not consider the implications of the way our waste is disposed in its biodegradability. How amazing would it be if more countries took on our waste as an energy resource to be incinerated!

    3. I wrote about LA's local water reclamation technology several times. It might be time to put together an update and a recap of past posts.

      It's fascinating and most people don't even know that LA and SoCal are leaders in the US. We also compare favorably globally.

  3. Thanks for taking the time to research and post this information! It's very useful and appreciated.


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