What is lyocell and how does it behave against the skin in heat?

The label says 100% lyocell and you are standing in a fitting room, unsure whether it sits closer to cotton or to polyester. Lyocell is a cellulose fibre made from wood pulp, usually eucalyptus, produced in a closed loop. Here is what that means for composition, heat, washing and how it compares to viscose.

What is lyocell and where does it come from?

Lyocell is a man made fibre of natural origin: it comes from dissolved wood pulp, not from petroleum. The manufacturer shreds eucalyptus, beech or pine, dissolves it in a non toxic solvent and pushes it through spinnerets to form the fibre. The solvent returns to the process, which is why lyocell counts among the cleaner cellulose fibres.

The trade name you will see most often on a label is Tencel. It is the same fabric under a specific producer's brand. If the tag reads Tencel Lyocell, you are looking at one material described by two words, not a blend of two fibres.

Across the dresses range lyocell usually appears in a blend, alongside viscose or cotton. That pairing gives a fabric with a soft hand that holds its shape better than pure viscose.

Is lyocell natural and kind to skin?

Lyocell is not a natural fibre in the sense that cotton or linen are, but it is plant based and well tolerated by sensitive skin. The difference is technical: cotton grows as a finished fibre, lyocell has to be manufactured from cellulose. On skin the result is often gentler than cotton, because the fibre surface is smoother and irritates less.

Three properties that matter in daily wear:

• Absorbency. Lyocell takes up moisture more effectively than cotton, so it moves perspiration away from the skin instead of holding it against the body.
• Fibre smoothness. The surface is uniform, with no protruding ends, which is why the material rarely irritates atopic skin.
• Odour resistance. A dry surface limits the bacteria responsible for smell, which translates into less frequent washing.

If you are choosing between compositions, it is worth comparing lyocell with a cotton base from t-shirts and tops: cotton breathes better in full sun, lyocell moves moisture away faster during a long day.

If your skin is prone to atopic reactions, watch something other than the fibre itself. Dyes and finishing treatments cause most reactions, not the material, so pale untreated shades are often a safer choice than intense colours.

One caveat: smoothness cuts both ways. Lyocell can build static in dry air, especially in heated interiors during winter.

Is lyocell environmentally sound?

Lyocell is produced in a closed loop where more than 99% of the solvent returns to production, which places a lighter burden on the environment than conventional viscose. The difference lies in the chemistry. Viscose requires carbon disulphide, a substance harmful to workers and groundwater. Lyocell uses an amine oxide solvent that circulates in a sealed system instead of reaching wastewater.

The second argument is the raw material. The wood usually comes from eucalyptus plantations, which grow quickly and do not need irrigation on a scale comparable to cotton.

There is a limit worth keeping in mind. Composition alone does not make a garment sustainable if the piece survives a single season. Here the wet strength of lyocell has a practical meaning: a piece that withstands more washes without losing shape stays in the wardrobe longer.

How does lyocell behave in heat and between seasons?

Lyocell performs well above 25°C, because it moves moisture faster than cotton and dries in contact with skin. That is why it reaches summer dresses and lightweight trousers. In heat it does not cling like polyester, though it does not breathe as freely as linen either.

Worn with trousers in a simple cut it holds a clean vertical line, because the weight of the fabric pulls it down instead of letting it stand away.

In light it shows its signature quality: a matte sheen that turns into a soft glow as you move, instead of flashing at single points the way satin does. The fabric falls into heavy, fluid folds, which is why long shapes in lyocell hang vertically and do not stand away at the hips.

For early autumn lyocell works as a base layer. A dress in this composition sits comfortably under sweaters and a blazer, because it adds no bulk of its own. It provides no warmth on its own, so treat it as a foundation rather than an outer layer.

How do you wash and iron lyocell without shrinking it?

Wash lyocell at 30°C on a delicate cycle, with a spin no higher than 600 rpm. Higher temperatures cause shrinkage, and a hard spin sets creases so firmly that ironing barely removes them.

Two rows are worth remembering. Drying flat solves most problems, because wet lyocell is heavy and stretches under its own weight, particularly across the shoulders. Ironing inside out protects the matte finish, which is the most attractive thing about this fabric.

One more note on frequency. Lyocell does not need washing after every wear, because the dry fibre surface limits odour causing bacteria. Airing overnight is enough in most cases, and washing less often extends the life of the fabric more than any fabric softener.

How do you recognise lyocell in a shop without reading the label?

You will recognise lyocell by three things at once: a cool touch, a matte finish and a weight that pulls the fabric downwards rather than letting it stand away. Take an edge of the fabric in your hand and release it. Lyocell drops vertically into narrow folds, polyester springs back and holds its shape, cotton stops somewhere in between.

The touch test can mislead you in blends, so it helps to know the typical compositions:

• Above 70% lyocell. The material behaves as described: cool, heavy, matte. This is what you find in simply cut dresses and relaxed trousers.
• Lyocell and viscose in equal parts. A softer hand and a lighter fabric, but also more prone to creasing after a full day.
• Lyocell with up to 5% elastane. Stretch arrives while the coolness stays. This blend most often reaches fitted shapes.

What not to do with lyocell

Three mistakes after which the fabric will not return to form:

• Never tumble dry it. Shrinkage reaches several percent in a single cycle, and on a midi dress that difference shows at the knee.
• Never bleach it with chlorine. Chlorine breaks down cellulose and leaves yellow discolouration that cannot be removed.
• Avoid hanging wet pieces on a thin hanger. The weight of the water stretches the shoulders, and once dry the bumps stay where the hanger sat.

Does lyocell crease?

It creases less than viscose and linen, and more than polyester. Creases from a day of sitting usually fall out overnight on a hanger, without ironing.

Is lyocell warm?

Not on its own, because it carries heat away together with moisture. On cool days it needs an outer layer, for example a piece from coats and jackets.

How does lyocell differ from viscose and modal?

All three belong to the same cellulose family, but lyocell is the strongest of them when wet. Viscose loses strength and stretches easily once damp, modal sits in the middle. In t-shirts and tops you will more often meet modal, in woven dresses lyocell.

Does lyocell pill?

Less often than wool and acrylic, because the fibre is long and smooth. Pilling appears mainly where friction is constant: under the arms, at a bag strap, along the inner thigh.

Back to that label in the fitting room. 100% lyocell means a fibre made from wood, cool to the touch, matte in light, asking for 30°C and flat drying. If you want a fabric that carries you through summer and moves into September under a knit, it is one of the more sensible compositions in matching sets.