I thought I’d bring together a few scattered thoughts and links on rayon production and processes in one post, but beware, this is an overview and not an in-depth study of rayon production. When I mentioned working with rayon-made-from-hemp the other day, I started digging around for information on rayon production. Whew- what a lot of information to wade through! I don’t want to embarrass myself by trying to talk about physics or chemistry. If you’re interested in those aspects of rayon production, then please do follow the links.
I’ll break Rayon into three parts: Definition, Manufacturing/Sustainability, and Practical Use.
Definition: A Man-Made Natural Fiber
Rayon was discovered by Count Hilarie de Chardonnet in the 1884. (Some sources claim it’s much earlier.) He and Louie Pasteur (yes, that Pastuer) were looking for a cheap alternative to silk when France’s silk moths were under threat from disease.
Rayon derives from natural fibers, usually wood pulp or cotton, and is processed and chemically re-arranged to form strands of fiber which produce a soft, absorbent, drapey fabric.
The process varies, and has changed over the decades but most of my sources agree it goes like this:
To make rayon, sheets of purified cellulose are steeped in caustic soda, dried, shredded into crumbs, and then aged in metal containers for 2 to 3 days. The temperature and humidity in the metal containers are carefully controlled.
After ageing, the crumbs are combined and churned with liquid carbon disulfide, which turns the mix into orange-colored crumbs known as sodium cellulose xanthate. The cellulose xanthate is bathed in caustic soda, resulting in a viscose solution that looks and feels much like honey.
Manufacturing and Sustainability:
Since the roughly the mid-90’s, (judging by the literature I found) manufacturers searched for a cheaper way to produce rayon with fewer toxic by-products. One way way is electronic beam processing:
Electron processing renders the cellulose more
accessible to chemicals and reduces the amount of alkali,
carbon disulfide, and acid used in the process. In addition
to potential savings of about US $3 million per annum
for a typical plant, the lower chemical demand translates
into reduced emissions of polluting chemicals. Electron
processing may allow a plant to stay in operation under
current emission standards, or expand its operation
without the need for further pollution control.
Tencel is another type of rayon, made from Euclyptus pulp. The process sets Tencel/Lyocell apart from other rayons because it is a closed-loop system. That means that it reuses the waste created in the process. That’s nifty.
Another aspect of rayon and textile sustainability involves the fibers used to make the rayon in the first place. Most of the time, bamboo sold for clothing is actually rayon. The material began life as a bamboo shoot, but went through one of the processes outlined above to become a fabric.
Hemp, too. Hemp is my favorite fiber because of its sustainability cred, but I admit I’m a little conflicted about wearing hemp rayon jersey. Is hemp or bamboo jersey more or less sustainable than cotton or other rayon? Probably. Both hemp and bamboo grow much more quickly with fewer chemicals and less water usage than cotton. Both bamboo and hemp grow exponentially quicker than wood.
Practical Use (subjective opinion!):
I don’t like sewing with rayon jersey. There, I said it. In my experience, rayon jersey pills if I look at it sideways and begins to stink after the first sweat. It’s maddening to sew- much more wiggly than regular t-shirting fabrics. The bindings and design details tend to crumple in the wash, even when I’m careful to take everything out and dry it immediately.
Plus- I noticed that bamboo jerseys tend to “grow” just like knitted garments made with bamboo yarn. Any knitters out there notice that? It’s the same, the hem creeps slowly downwards. I have yet to find any bamboo fabric that doesn’t pill (some are better than others), it grows, and it is extra wiggly compared to regular rayon.
The hemp-rayon jersey may be different. I have a swatch that has gone through six loads of washing thus far without pilling. I’m impressed. It’s not as “wiggly” either, and has a nice lightweight but firm hand. The hemp rayon differs from hemp jersey- I used some of that last year for a dress and two shirts- plain hemp jersey(mixed with organic cotton and a whiff of lycra) is somewhat heavy and curiously “nubbly.” This hemp rayon is smooth and extremely lightweight. I have some purple I’ll use later this month for June’s hack…