Sustainability claims in the textile industry are easy to make and difficult to verify. Most consumers have no mechanism to assess whether a brand's environmental positioning reflects what is actually happening in production. Here is exactly how TENCEL Lyocell is made, why the process differs from conventional fiber manufacturing, and what that means for the fiber that ends up against your skin.
Bellissima makes TENCEL workout clothes from this fiber.
TENCEL Lyocell is one of the few cases where the production process is documented, third-party assessed, and specific enough to evaluate on its own terms.
Step 1: Raw material sourcing
TENCEL Lyocell starts with eucalyptus wood pulp. Lenzing AG, the Austrian company that produces TENCEL under a proprietary process, sources its eucalyptus from sustainably managed forests certified by the Forest Stewardship Council, according to Lenzing's supply chain documentation published in its annual sustainability report.
Eucalyptus is used specifically for its cultivation profile. It grows to harvest maturity faster than most hardwoods, typically in under ten years. It requires no irrigation beyond natural rainfall in the South African and Chilean regions where Lenzing sources its primary supply. It requires no pesticides or fertilizers during cultivation. The land footprint per unit of fiber produced is significantly lower than cotton cultivation, which requires irrigation at approximately 10,000 liters of water per kilogram of fiber according to research published by the Water Footprint Network (Mekonnen and Hoekstra, 2011).
Step 2: Pulping
The harvested eucalyptus wood is broken down into pulp through a mechanical and chemical process that separates the cellulose from lignin and other wood components. The resulting pulp is a white, fibrous cellulose material that serves as the raw input for fiber production.
Lenzing holds Forest Stewardship Council chain-of-custody certification for this stage, meaning the traceability of the pulp from certified forest to production facility is third-party verified.
Step 3: Dissolution in NMMO
The cellulose pulp is dissolved in a solvent called NMMO, which stands for N-methylmorpholine N-oxide. This is the step that most distinguishes TENCEL Lyocell from conventional regenerated cellulose fibers like rayon and bamboo viscose.
Conventional viscose and bamboo viscose production uses sodium hydroxide and carbon disulfide as the primary solvents. Carbon disulfide is a toxic compound. Exposure during manufacturing is associated with neurological and cardiovascular health effects, according to the US National Institute for Occupational Safety and Health. Most conventional viscose production is open-loop, meaning these solvents are not systematically recovered after use.
NMMO, the solvent used in TENCEL Lyocell production, has been assessed by the European Chemicals Agency as significantly less hazardous than carbon disulfide. More importantly, the TENCEL Lyocell process is designed around solvent recovery from the outset.
Step 4: Extrusion through spinnerets
The dissolved cellulose solution is pushed through spinnerets, which are metal plates containing thousands of tiny holes. Each hole shapes the solution into a filament as it is extruded. The diameter of the spinneret holes determines the fineness of the resulting fiber.
As the filaments emerge from the spinnerets, they pass through an air gap and then into a water bath, where the cellulose solidifies back into fiber form as the NMMO dissolves away. The fiber at this stage is a continuous filament of regenerated cellulose.
Step 5: The closed-loop solvent recovery
This is the step that defines TENCEL Lyocell's environmental profile. As the cellulose fibers are washed and the NMMO dissolves into the water bath, the resulting NMMO-water solution is collected and processed through an evaporation system that removes the water and concentrates the NMMO back to usable solvent strength.
Lenzing recovers more than 99% of the NMMO solvent in each production cycle, according to the company's published sustainability data. The recovered solvent is returned directly to the dissolution step and reused. This closed loop means that the chemical input to the process is largely retained within the system rather than being discharged as waste.
The water used in the process is also treated and recycled within the facility. Lenzing holds ISO 14001 environmental management certification, which requires documented management of water use, emissions, and waste across the production system.
Step 6: Cutting, drying, and finishing
The continuous filaments are cut into staple fiber lengths appropriate for spinning into yarn. The fibers are washed, dried, and treated with a small amount of finish to aid processing in textile mills. The finishing agents used in TENCEL Lyocell production are assessed under OEKO-TEX Standard 100 certification requirements, which test for harmful substances in the finished fiber.
The dried, finished staple fiber is then compressed into bales and shipped to textile mills, where it is spun into yarn, woven or knit into fabric, and eventually cut and sewn into garments.
What the process produces
The fiber that results from this process is a regenerated cellulose material with specific physical properties: hygroscopic moisture management, smooth fiber surface, longer fiber length than cotton, and tensile strength maintained when wet. A 2014 study in Fibers and Polymers by Kaplan et al. confirmed the moisture management advantage over cotton in active wear conditions as a consequence of the fiber's structural properties.
These properties are inherent to the fiber structure. They are not applied through chemical post-treatment, which means the garment does not carry the additional chemical layer that synthetic performance finishes add to conventional activewear.
Why the production process matters for what you wear
The production story matters because fiber properties and production practices are connected. A fiber produced through a process that generates minimal chemical waste and uses a recoverable, lower-hazard solvent is also a fiber that does not require post-production chemical treatments to achieve its performance characteristics. The cleaner the process, the fewer chemical inputs end up in or on the finished fiber.
Bellissima's Sempre Leggings and bras use 92% TENCEL Lyocell. The production process described above is exactly what goes into the fabric against your skin. That is not a marketing claim. It is a documented manufacturing process with third-party verification at multiple stages.
The short version
Eucalyptus pulp, dissolved in a recovered solvent, extruded into fiber, washed in a closed loop that captures more than 99% of the solvent, cut and dried into staple fiber. That is how TENCEL Lyocell is made. The process is as clean as fiber manufacturing currently gets at commercial scale.
Sources
Lenzing AG. (2023). TENCEL Lyocell production process and sustainability data. Lenzing Sustainability Report.
European Chemicals Agency. (2023). Substance evaluation: N-methylmorpholine N-oxide. ECHA Chemical Safety Reports.
Kaplan, S., et al. (2014). Thermal comfort of lyocell and other fibers in active wear. Fibers and Polymers, 15(6).
Forest Stewardship Council. (2023). FSC chain-of-custody certification standards. FSC International.
Mekonnen, M.M., and Hoekstra, A.Y. (2011). The green, blue and grey water footprint of crops and derived crop products. Hydrology and Earth System Sciences, 15(5).
US National Institute for Occupational Safety and Health. (2020). Carbon disulfide: Occupational exposure and health effects. NIOSH Pocket Guide to Chemical Hazards.
OEKO-TEX Association. (2023). OEKO-TEX Standard 100 testing criteria. OEKO-TEX Technical Bulletin.
