About Lyocell Fibers

Lyocell is a manufactured fiber made from natural cellulose — wood pulp, usually from managed eucalyptus, beech or spruce — dissolved and regenerated into a new fiber. It belongs to the same broad family as rayon and modal, but the process that makes it is different in the way that matters most: lyocell pulp is dissolved directly in an amine oxide solvent (NMMO) and spun in a closed loop, so the solvent is recovered and reused instead of being consumed in chemical reactions.

That process gives lyocell a distinctive physical profile. The fibers are smooth and round in cross-section, they are strong for a cellulosic fiber — and unusually, they keep much of that strength when wet — and they absorb moisture readily, which is why lyocell fabrics feel cool and dry in warm weather and have become a mainstay of premium shirting, denim, bedding and activewear blends.

The Closed-Loop Solvent Process

Lyocell production starts with wood pulp sheets that are shredded and dissolved in hot NMMO to form a clear, honey-like dope. The dope is filtered and extruded through spinnerets into a water bath — dry-jet wet spinning — where the cellulose regenerates as continuous filaments that are washed, finished, dried and either cut into staple fiber for spinning or kept as filament yarn. The spin bath liquid is purified and the NMMO is recovered at very high rates, which is the fact behind the closed-loop description of the process.

Compare that with the viscose process on the viscose page of this site: there, cellulose is chemically converted with caustic soda and carbon disulphide into a xanthate, then regenerated. Lyocell skips the xanthate chemistry entirely — the cellulose is dissolved physically, not derivatized — which changes both the environmental profile of the plant and the structure of the fiber that comes out.

Properties in Fabric

Lyocell fibers have a smooth surface and a highly oriented internal structure, so yarns are strong, fabrics drape fluidly, and the surface feels sleek rather than fuzzy. Moisture absorption is high and the fiber moves moisture through the fabric, which is why lyocell shows up in warm-weather shirts, sheets and underwear. In denim, a lyocell share gives jeans a softer hand and better drape while keeping a cotton-rich look.

One working characteristic mills plan around is fibrillation: under wet abrasion, the fiber surface can split into tiny fibrils, giving a peach-skin or frosted effect. Producers treat that as a tool as much as a problem — controlled fibrillation creates soft-touch finishes, while cross-linked lyocell types are made to resist it where a clean, smooth surface must survive many washes.

Lyocell, Tencel and Modal

Lyocell is the generic fiber name. Tencel is a brand name under which lyocell (and modal) fibers are sold by their producer, Lenzing, so a Tencel lyocell garment and a generic lyocell garment describe the same fiber type from different supply routes — the brand page on this site covers that distinction in full. Modal is a cousin, not a twin: it is also regenerated cellulose, but made by a modified viscose process tuned for wet strength and softness, and it behaves differently in dyeing and finishing than lyocell.