Modal, Viscose, Bamboo, TENCEL: What Sleepwear Labels Actually Mean
Stand in front of a rail of soft sleepwear and you will see four words used almost interchangeably: viscose, modal, bamboo and TENCEL. They are not interchangeable, and only two of them are actually fibre names.
This is the short guide to reading the label rather than the swing tag.
Viscose is the family, not the fibre
Viscose — called rayon in the US — is the umbrella term for regenerated cellulose: plant cellulose that has been dissolved into a solution and re-spun into filament. It is neither natural in the way cotton is, nor synthetic in the way polyester is. It sits in a third category, and that category is where most soft, drapey, affordable fabric lives.
Ordinary viscose is fine to wear and noticeably weaker when wet. That wet-strength weakness is why a lot of viscose garments carry a dry-clean label and why they lose shape faster than you would expect.
Modal is a specific type within that family
Modal is a modified viscose, engineered for higher wet strength and a finer, smoother fibre. It is usually made from beech pulp. The practical differences that follow are the ones you can feel and test:
- It survives machine washing where ordinary viscose often does not.
- It absorbs more moisture than cotton and releases it more readily, so it stays dry against the skin longer.
- The uniform fibre gives a smoother surface with fewer loose ends, which is why it resists pilling.
So "modal" on a label tells you something real. "Viscose" alone tells you much less.
TENCEL is a brand, not a fibre
TENCEL™ is a trademark of Lenzing, the Austrian producer. It covers two fibre types: TENCEL™ Modal and TENCEL™ Lyocell. Lyocell is another regenerated cellulose fibre, made with a solvent process that is run closed-loop — the solvent and water are captured and reused rather than discharged.
Seeing TENCEL on a label tells you the producer and, by extension, something about the process. Seeing "lyocell" or "modal" with no producer named tells you the fibre type but nothing about the mill. Both pieces of information are worth having, and the second one is the one brands usually leave out.
Bamboo is where it gets misleading
This is the one to watch. Bamboo grows fast, needs little water and no pesticides, which is a genuinely good story — and it is a story about the plant, not the fabric.
Almost all soft "bamboo" clothing is viscose made from bamboo pulp. The bamboo is dissolved and re-spun exactly like any other viscose, using the same chemistry. By the time it is fabric, the environmental profile is the profile of the viscose process, not of the growing plant.
Regulators have taken this seriously: the US Federal Trade Commission has pursued retailers for marketing rayon as "bamboo", and its guidance requires such fabric to be labelled as rayon or viscose made from bamboo rather than simply "bamboo". If a label says only "bamboo", it is not telling you what you are buying.
There is such a thing as genuine bamboo linen — mechanically processed rather than dissolved — but it is rare, expensive, and feels like linen rather than like the silky fabric people associate with the word.
The cheat sheet
| Word | What it is | What it tells you |
|---|---|---|
| Viscose / rayon | The whole regenerated-cellulose family | Very little on its own |
| Modal | A specific fibre within it | Higher wet strength, finer fibre, machine washable |
| Lyocell | Another fibre within it | Closed-loop solvent process |
| TENCEL™ | A Lenzing brand covering both | Names the producer, so the process is traceable |
| Bamboo | Usually a raw material, not a fabric | Where the pulp came from — and nothing else |
Three questions worth asking
- What is the full composition? Not the headline fibre — the percentages. A set that is 95% modal and 5% elastane behaves very differently from one that is 60% modal and 40% polyester.
- Is the processing closed-loop? This is the question that separates a good cellulose fibre from a polluting one, and it applies to modal, lyocell and bamboo viscose alike.
- What are the wash instructions? They are the most honest thing on the garment. A soft fabric that says dry clean only is telling you it is ordinary viscose.
Our Modal Cloud sets are typically 95% modal and 5% elastane, machine washable at 30°C — the Summerhouse long set is a representative example, composition printed on the label rather than implied by the swing tag. If you would rather have a straightforward natural fibre, the organic cotton range is the other honest answer — and the pyjama fabric guide compares them side by side.
