What is the difference between lyocell, modal, bamboo and viscose?

These four names appear on labels as if they were four different materials. Chemically they are the same polymer, cellulose, and the fibre in each case is made by dissolving pulp and squeezing it through a spinneret. What differs is how the dissolving is done, and that turns out to control everything the wearer experiences.

Step by step

1. Start with viscose, the original.Pulp is treated with caustic soda and carbon disulphide, then regenerated in an acid bath. The resulting fibre has a disordered internal structure: soft and drapey, absorbent, weak when wet, and prone to shrinkage and water spotting.
2. Move to modal.A modified viscose process with a stretched, more highly oriented fibre. That orientation gives significantly better wet strength and dimensional stability. Modal machine washes at 40, resists shrinkage well, and is common in underwear, t-shirts and bedding.
3. Then lyocell.A completely different route: pulp is dissolved directly in a non-toxic amine oxide solvent that is recovered and reused in a closed loop. The fibre is highly crystalline, strong wet and dry, resistant to shrinkage, and it takes moisture management better than the others. It is sold widely as Tencel.
4. Place bamboo honestly.Bamboo grows fast and needs little input, but turning it into soft fabric almost always means the viscose process. The label may say bamboo viscose, viscose from bamboo, or just bamboo. Treat it as viscose in the wash. Lyocell made from bamboo pulp also exists and is better on both counts.
5. Compare what you will actually notice.Drape and softness: viscose and modal best. Wet strength and durability: lyocell clearly best, modal second. Shrinkage risk: viscose worst by a distance. Pilling: lyocell resists it best; modal is good; viscose in a loose knit pills readily.
6. Match the wash to the fibre.Viscose and bamboo viscose: hand wash cool, dry flat. Modal: machine wash 40, low spin, air dry. Lyocell: machine wash 40, tumble low if the label allows, though air drying is still kinder.
7. Read the blend, not the headline.Most garments mix these with cotton, polyester or elastane. The blend rule applies: the most fragile fibre present sets the care.

Tips

• Tencel is a brand name owned by Lenzing and covers both their lyocell and their modal. If a label says Tencel it should also say which of the two it is.
• Lyocell has a tendency to fibrillate — fine fibrils lift from the surface — which manufacturers use deliberately to create a peached, suede-like finish. It also means harsh washing gives an unwanted fuzz.
• Cost usually tracks the process: viscose cheapest, modal in the middle, lyocell most expensive. In this family, paying more genuinely buys a better fibre.
• If a bedding or t-shirt label just says bamboo with no further detail, assume viscose and wash it cool.

Alternatives

• Cotton: Stronger wet, less drapey, more prone to creasing, and cheaper. The right choice where the garment needs to be robust rather than fluid.
• Cupro: Another regenerated cellulose, made from cotton linter. Silky, breathable and often used as a lining. Behaves much like viscose in the wash.
• Acetate and triacetate: Also cellulose-derived but chemically modified rather than regenerated. Silky, heat-sensitive and usually genuinely dry clean only — acetone dissolves it, so nail varnish remover destroys it instantly.

Questions people ask