The Life Cycle of Tencel
Recently, we decided to use Tencel in our new clothing line. We did it because the voices on the internet told us that “Tencel is a sustainable fiber...” and we believed them. We received results from brands, bloggers, journalist, influencers and anyone in-between presenting facts and figures about the sustainability of the fiber. However, what we didn’t see, were sources to facts or figures of any reputable source. So we decided to create this page. The goal was simple - be helpful. Be helpful to anyone that wants dig a little deeper and provide sources to all data, and in many cases original sources. We wanted to discuss the good, the bad and the unknown. Most importantly, we didn’t want to be afraid of showing all the facts. Hopefully we did that.
We created a short and long version. The short is just what you see as you scroll the page. The long version is accessible by clicking on the images and text. The long version is where you will see the full story and links to learn more.
JUST A QUICK HISTORY
Rayon: A textile fiber or fabric made from regenerated cellulose.
TYPES OF RAYON
MAKING OF TENCEL
Most of the wood used in Lenzing’s Tencel production is derived from eucalyptus (South Africa), beech (Europe), pine (USA), birch (Europe) and spruce (Europe) trees. All wood is sourced from FSC or PEFC certified forests/semi-forests/plantations.
Wood is a fantastic renewable resource that Lenzing also uses to fuel their Austria and Czech Republic plants. If sourced correctly, minimal environmental concerns exist. The major concerns would be the effects of groundwater usage and depletion of soil nutrients on natural ecosystems.
Once cut, the logs are transported to a wood chipping facility and chopped into small pieces. These pieces are then transported to a pulp facility for further processing. Some pulp facilities will have the wood chipping process done on-site.
The wood chips are placed in a solution of water, caustic soda (using mercury free technology) and sodium sulfide. An elemental chlorine free (ECF) or totally chlorine free (TCF) bleaching process is used. Both are considered to have a low environmental impact. One of the biggest environmental concerns with pulp production is the energy demand. Lenzing overcomes this by having their own pulp production facilities that use 100% renewable energy. However, only about 50% of all pulp comes from Lenzing facilities while the other 50% is imported. We would consider pulp production the biggest concern from an environmental standpoint.
This is where the magic happens. A little science (NMMO) turns the wood pulp into a regenerated cellulose fiber called lyocell. NMMO is the only chemical solvent needed and the compound itself, and effluent are considered to be non-toxic. The best part about the NMMO solution is that 99% of it can be recycled and used again! SPINNERET The solution is pushed through small holes and the fiber starts to form on the other side.
It's first treated with a diluted NMMO solution and then demineralized water. This helps strengthen the fiber.
To help with pilling and fuzz, a simple enzyme treatment is used. This gives the end fabric a softer and more peach-skin feel.
The fibers dried and then spun into yarn or thread for final production. They can be spun with other materials as well.
BIODEGRADABILITY OF LYOCELL
Keeping this short and simple - Yes, Tencel is 100% biodegradable/compostable. The image below demonstrates lyocell's biodegradability in surface soil over 16 weeks.
Keeping this short and simple - Yes, Tencel is 100% biodegradable/compostable. The fiber has a highly crystalline structure which means two things for us: it’s strong and does not biodegrade easily. The highly crystalline structure gives the end fiber an increased tensile strength that is stronger than cotton and other forms of regenerated cellulose fibers. However, having a highly crystalline structure also prevents it from easily biodegrading. While that might sound bad, it’s not. If consumers keep their clothes away from landfills, the high tensile strength of Tencel should give garments/products a long life! And because Tencel will biodegrade, when the fiber ends up in the ground, it will eventually do so! It just takes a little more time.
In surface soil, Tencel takes about 16 weeks to fully biodegrade. Rayon degrades in roughly 3 weeks and cotton in roughly 5½ weeks. If disposed in landfills, the amount of time is impossible to determine. The correct answer is: keep your items out of landfill by keeping them, selling them, donating them or disposing of them in other fashions. A few quick tips - ask the brand if they take back unwanted items, many (including us) do! You can also look for clothing bins!
The future is all about NMMO and the types of cellulose and derivatives that is can be used with. Below is the process of turning cutting room cotton scraps back into a usable fiber. The processes is called REFIBRA.
The future of Tencel has more to do with the NMMO solution. Since NMMO is non-toxic, easily made and 99% recyclable, the expansion of mixing it with different types of cellulose and its derivatives seems to be a hot topic.
Lenzing is currently in production with a new Tencel that uses a technology called REFIBRA. The process is exactly the same as Tencel but part of the cellulose input is derived from pre-industrial cotton scrapes - mostly from cutting rooms. Those scraps are turned into pulp and then blended with wood pulp. After that, the Tencel process continues as usual.
- Cotton scraps that are usually landfilled can be reused.
- Lenzing claims the ReFriba process uses 95% less water compared to conventional cotton. From my research, that seems well within the standard deviation of regular Tencel. No data exists on the comparison of REFIBRA and with the regular Tencel process.
The idea is extremely cool and while it’s new, it seems to have a huge potential. When talking to Innovation In Textiles, Tricia Carey of Lenzing mentioned, post-consumer waste is the next goal of the REFIBRA technology. If successful, the environmental implications would be tremendous! Remember, only fabrics or clothes derived from 100% cellulose would be applicable at the moment, polyester blends would not. I should note that more research is needed in the Life Cycle Assessment before a definite conclusion but I can only assume it will be positive as scraps are used instead of virgin materials.
Lastly, I was not able to find the exact amount of cotton to wood pulp ratio used in the REFIBRA process. I’m sure it’s proprietary. What I did find was that Lenzing’s Tencel using REFIBRA technology is part of Recycled Claim Standard which is a “chain of custody standard to track recycled raw materials through the supply chain.” From my understanding, the standard will track any product with 5% of its content being of recycled origin. Not significant but worth noting.