Tencel :: Sustainable but not necessarily healthy

TENCEL® has gained favorable acceptance within the mainstream fashion industry and also in the eco-fashion industry as being a natural fiber that has a flattering drape and is soft, luxurious, breathable, naturally wrinkle-resistant, and environmentally sustainable.

TENCEL® is the brand name owned by Lenzing Fibers of Austria for a recently improved fabric from a fiber generically called lyocell.  The name “Tencel” has gained popular acceptance but the fabrics that are popularly called “Tencel” are actually lyocell.  We will use the proper generic name lyocell.  Remember that TENCEL® is just the brand name for a type of lyocell.  According to Michael Kininmonth, a spokesman for Lenzing Fibers, "the blend composition of a fabric must be a minimum of 30% TENCEL® to be able to use the brand name."

Most people assume that there are two broad categories of fibers: natural fibers like cotton, wool, hemp, ramie and silk; and artificial fibers synthesized out of petrochemicals like nylon and polyester. Lyocell falls somewhere in-between. The raw material for lyocell is cellulose from wood pulp which is broken down chemically in a soupy sludge that is squirted out a showerhead spinneret and reformed as fibers. Lyocell is more accurately described as a recovered or regenerated fiber, although the folks at Lenzing Fibers make a distinction between regenerated fibers and lyocell which they describe as a "solvent spun fiber" that keeps the cellulose structure closer to that found in nature.

The environmental press has often heralded lyocell as a new fiber that represents a milestone in the development of environmentally sustainable textiles.  Lyocell is made from cellulose found in wood pulp which has been harvested from tree farms. Cellulose is the natural polymer that makes up the living cells of all vegetation. The fiber is produced via an advanced 'closed loop' solvent spinning process, with minimal impact on the environment and economical use of energy and water. Lyocell uses an amine oxide as a non-toxic solvent which is continually recycled during the production process. Production plant emissions into the air from smokestacks and from wastewater are significantly lower in comparison to many other man-made fiber operations.

As with conventionally manufactured cotton fabric, there are many steps and processes involved in taking lyocell from fiber to fabric.  The major steps are:

1. Creating a solvent solution from wood pulp
2. Spinning lyocell fiber from the solvent solution
3. Washing lyocell fiber to remove solvents
4. Dyeing fiber and producing yarns
5. Finishing to produce lyocell fabric

The MSDS (Material Safety Data Sheet) for lyocell rates the amine oxide solvent used to digest the wood pulp as being non-toxic and about 99% is recovered and recycled during the manufacturing process.  Waste products in the air and water from the manufacturing process are minimal and considered harmless. Lyocell fiber is eco-friendly since products made from it can be recycled and lyocell is biodegradable because it is a cellulosic fiber.  Products made from lyocell can be recycled, incinerated, or digested in sewage. The fiber will usually degrade completely in just eight days in waste treatment plants.

The process to manufacture lyocell fiber is in fact very nearly a closed loop process in which bleach is not required.  Bleach is commonly required in fabric manufacturing, especially for cotton.  For this reason, high quality lyocell products contain no free chlorine and are sold as so-called "TCF - products".  The European Union awarded this process the Environmental Award 2000 in the category "technology for sustainable developments".  There are currently only four manufacturing facilities that produce lyocell fibers: one in the U.S., two in Europe, and one at the Birla Industries plant in India.   Processes, including the chemicals that they use for finishing, can vary. 

While production of lyocell fibers is generally eco-friendly and environmentally sustainable, the transformation of lyocell fibers into fabric and garments can use many or the same harsh, and even toxic, chemicals and processes used in conventional garments.  This is because of two properties of lyocell: it doesn’t always accept dyes well, and it has an inherent tendency to fibrillate or “pill”.  In wet processes the surface of lyocell fibers begins to peel away.  These hairs on the fiber surface are called fibrils.  When controlled in the correct way, the fabric is given a "peachskin" surface.

Lyocell fiber has a relatively low surface energy, which makes it difficult for dyes to bind to it.  Depending upon their ideological leanings, the manufacturing facility might use a variety of chemical processes, enzyme baths, and dye treatments which might, or might not, be eco-friendly.  Enzymes are bio-chemicals used to weaken surface hairs on fabrics so they can be removed to prevent excessive pilling.  Enzymes do occur in nature and are responsible for the breakdown of leaves and vegetation on the forest floor, for example.  This is in keeping with the Lenzing Fibers goal of using low impact chemistry in their fabric manufacturing.

The manufacturing of lyocell fiber does have significant environmental and ecological benefits. Most of concern about lyocell comes from the sometimes heavy use of chemicals to turn lyocell fiber into garments.  Tencel® and lyocell are possibly not appropriate for those with Multiple Chemical Sensitivities.  My suggestion for people with chemical sensitivities that are interested in purchasing apparel made from Tencel® and lyocell is to proceed carefully and to shop for lyocell garments manufactured in Europe or the U.S.  Sustainable clothing and eco-friendly clothing have great value to the earth but they are not the same as organic clothing.

Enjoy.

Michael
LotusOrganics.com

[Note: This article has been updated to reflect some additional information and clarifications about the lyocell manufacturing processes that was been sent to us by Lenzing Fibers spokesman Michael Kininmonth. We are highly appreciative of their efforts to reach out and provide more facts and details.  The closed-loop manufacturing process make lyocell the most eco-friendly of the regenerative fibers but the use of chemicals still creates health problems for most people with chemical sensitivities.]