What a composition label tells you — and what it does not

1. The product name is not the composition

Uniqlo sells a shirt called “AIRism Baumwolle T-Shirt” — Baumwolle being German for cotton. Its stated composition is 53 % cotton, 30 % recycled polyester, 17 % elastomultiester. Nothing about that is hidden: the figures sit on the product page, and AIRism identifies the brand’s technical fabric line, where the synthetic share is the whole point.

But the shirt sits next to a 100 % cotton one, at the same price, in the same category. Reading the name instead of the composition line gets you a different fabric than you thought. This is the single most useful habit we can pass on: the name is marketing, the composition is the specification.

2. The label names the fibre class, not the grade

The same retailer sells a jumper listed as “100 % Merinowolle Pullover”. Its composition line reads: 100 % wool.

That is not a contradiction — merino is wool. But it shows the limit of the field. A composition statement is required to name what the fibre is, not how good it is. Merino covers a wide range of fineness, usually measured in microns, and a finer grade feels and performs very differently from a coarse one at the same “100 % wool”. The same applies to cotton: staple length separates a Supima from a commodity fibre, and neither shows up as a percentage.

Percentages describe what the fibre is. They say nothing about how good it is.

3. The same fibre can cost twice as much

We read four crew-neck t-shirts on the same day. Three state 100 % cotton, at 17.95 €, 19.90 € and 30 €. The most expensive is not made of a different fibre than the cheapest.

What might separate them sits in places the label never mentions: yarn quality and staple length, knit construction — one of the four names interlock, a denser double-knit — fabric weight, dyeing, seam finishing, and how the garment holds shape after washing. We did not measure any of it, so we will not tell you which is better made. What we can tell you is that the composition line will not answer that question for you either, and any guide that claims otherwise is filling a gap it cannot see into.

How to use this in a shop

Open the composition before the product name convinces you of something. Check whether the fibre matches what you actually want the garment to do — cotton for plain wear, synthetics where moisture management is the purpose, wool where warmth per weight matters. Then accept that everything beyond that — the difference between a good and a mediocre version of the same fibre — is not on the label, and treat price as a weak signal rather than proof.