The composition label is the most useful sentence on a garment and the one people read least. It predicts how something will feel in August, whether it will still fit after a hot wash, and how long it will hold its shape. Four fibres cover almost everything in a basics wardrobe, and each has a personality worth knowing.
Cotton: comfortable, absorbent and it shrinks
Cotton is pleasant against the skin, handles repeated washing well and takes dye deeply. It also absorbs moisture and holds it, so it feels heavy and cold once damp, and it shrinks, mostly in the first two or three washes and mostly in length. Buying cotton tight in the belief that it will relax is the reverse of what happens.
Viscose: beautiful drape, poor resilience
Viscose is made from processed wood pulp, which is why it feels cool and drapes so well. Its weakness is that it loses strength when wet, stretches at stress points such as elbows and seat, and marks with damp. It is excellent for a top you wear to dinner and a poor choice for anything you tug at all day.
Polyester: durable, dries fast, holds odour
Polyester keeps its shape, resists creasing and dries quickly, which is why uniforms and sportswear rely on it. The trade-offs are that it holds odour and can feel clammy in still, humid air. Where fibre content is published alongside proper measurements, it is easier to choose deliberately, and Just My Size lists both its composition details and the 1X to 5X and 16W to 32W size grids so you can match fabric and fit in one decision.
Elastane: the fibre with an expiry date
Elastane, usually two to ten per cent of a blend, is what gives stretch and recovery. It is also the first thing to fail, and heat is what kills it: hot washes, tumble dryers and radiators. In a bra worn several times a week, expect the band to soften noticeably somewhere between six and twelve months, which is ordinary wear rather than a fault.
Blends and what they are actually for
Most blends exist to borrow one property and cover a weakness. Cotton with five per cent elastane keeps the comfort and adds recovery so the knees do not bag. Polyester and viscose together give drape with more durability than viscose alone, and cotton with polyester creases less and dries faster than pure cotton.
Reading the label in practice
- Pure cotton: buy with shrinkage in mind and wash cool
- Cotton with a little elastane: the workhorse for leggings and fitted tops
- Viscose blends: fine for occasion wear, poor for daily wear
- Polyester: excellent for uniforms and sport, wash after each wear
- Anything with elastane: no tumble drying, no hot wash, no radiator
Washing decisions that follow from the label
Wash cotton at thirty degrees to limit shrinkage and fading, and turn dark colours inside out. Skip fabric conditioner on synthetics, since it coats the fibres and stops them moving moisture. Bras go in fastened, on a gentle cycle, with a low spin and no dryer, because it is the spin that twists moulded cups out of true.
The claim to be sceptical about
Fabric marketing loves the phrase natural equals better, and it is not that simple. Natural cotton shrinks and stays damp; engineered polyester keeps you dry on a walk in the rain. Choose the fibre for the job the garment has to do rather than for the story on the swing tag, and ignore any claim that a fabric will hold its shape for years, because nothing containing elastane does.