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Fibre composition

A composition declaration is a percentage of fibre mass. Buttons, zips, leather trims and interlinings are not in it. Several other figures on a passport inherit that denominator, which is why this is the field to get right first.

In force today
Sources as at
26 August 2026
On this page

What the field actually is

A fibre composition is a set of percentages over the fibre mass of the product. Two things follow from that sentence and both are routinely lost.

The denominator is fibre mass, not product mass. A metal zip, a horn button, a leather trim and a fusible interlining are all part of the garment and none of them is part of the composition. Leather sits in its own field rather than being folded in as a percentage.

And the percentages are not forced. Where a declaration does not add to 100, it is recorded as it stands rather than being renormalised into something tidier. A composition that adds to 97 is telling you something. A composition silently scaled to 100 has thrown that away.

Every figure downstream inherits that denominator, and we say so on the row.

The law that already applies

Almost everything written about textile passports is written in the future tense. Fibre composition is the exception. Regulation (EU) No 1007/2011 on textile fibre names and labelling is in force now, and it has been for years.

Annex I to the Regulation sets out a closed list of textile fibre names. Article 5(1) means a name that is not on that list may not be used as a fibre name. It is a vocabulary, not a guideline.

Our summary of Regulation (EU) No 1007/2011, Annex I and Art. 5(1), not a quotation from it. Consolidated text CELEX 02011R1007-20180215. In force. Our transcription of Annex I covers 62 fibre names with their synonyms and has not had a legal review.

The practical consequence turns up in live product data constantly. A garment described as 70 per cent bamboo has a problem, because bamboo is not one of the permitted names. The fibre it almost always refers to is viscose, and the correct name is the one the law recognises.

The same regulation carries a duty to make composition available before purchase, including in online selling, at Article 16(1). We link it here because a reader should have it, and we have not yet read that article in full against the Official Journal, so nothing on this page rests on it. That is recorded on the source list below rather than being quietly left out.

Whether a duty under this instrument reaches a particular business is a separate question with a separate answer. The applicability page covers who carries what.

How a declaration is read, and when it is refused

A composition can reach a passport from several places. A structured field the merchant already maintains. A variant option. A labelled block in a product description. And, sometimes, ordinary prose in a description that happens to contain the whole answer.

Prose is the interesting case, because it is where most systems either refuse everything or accept anything. The rule here is narrow. A description closes a composition only when it adds to exactly 100 across permitted fibre names with nothing in dispute. Anything short of that can propose a value for a person to confirm and cannot finish one.

Three refusals matter more than the acceptances.

Your own vocabulary is the authority

A term you list as a colour is not read as a fibre. Where a merchant has declared a structure, the declared structure beats a string that merely looks right, and a great many fibre names are also perfectly ordinary colour names.

A qualifier is not part of a name

Organic and recycled do not ride into a legal fibre name. They are separate claims with their own evidence, and one of them has a certification regime behind it that we do not treat as satisfied by the word alone.

A construction is not a fibre

A weave or a knit never implies a fibre content. Neither does a finish, a fabric trade name or a garment category. Where the composition is not stated, the honest output is the field left empty with a reason attached rather than a plausible guess.

One mapping is deliberately not made. Rayon is not treated as viscose, because in United States usage the word spans more than one of the legal fibre names and choosing one of them would be inventing information rather than translating it.

Two rows, side by side

Invented products, real value shapes. The point is the second one.

Two variants from a test catalogue. Merchant details are invented.
VariantWhat the store heldPassport valueState
Overshirt, size M metafield: 100% cotton Cotton 100% Resolved
Knit jumper, size L description: soft merino blend, colour: camel empty Not established

The second row could have been filled. Merino is a permitted fibre name and camel is a permitted fibre name, so a system reading strings would have produced a composition with two fibres in it, no percentages and a fabricated denominator. Camel is the colour of the jumper. The merchant said so, in their own colour option, and the merchant is right.

An empty box with a visible reason is worth more than a filled box that guessed.

What the reader gets instead is the field empty, the reason named and a question routed to the one person who can settle it. The vocabulary behind those two states is set out on the evidence page.

On the current 34 variant test catalogue this field resolves on 31 of 34 variants. That is a test catalogue rather than a customer, and it is the highest resolution rate of any field that depends on somebody outside the business.

What else on the passport depends on this

This is the field to fix first, and not because it is the most visible.

Several other attributes take fibre composition as an input. The modelled environmental figures need to know what the garment is made of before they can be produced at all. The microfibre supplement weights fibre categories, so a missing composition withholds the whole result rather than producing a smaller one, because a sum with a term dropped out of it gets quietly smaller and stays publishable and is wrong. A commodity code's last digits encode the dominant fibre, so a code cannot be checked against the garment until the composition is known.

We are not publishing an exact count of dependent fields yet. Our own records give two different numbers for it and reconciling them against the governed source is work that has not been done. Saying six or seven on the strength of the wrong one of those records would be a small error in a page whose subject is not making small errors.

Where the modelling stops

The French regulatory calculator we use for the environmental figures does not recognise every legal fibre name. At the version we pin, 22 of 49 fibre names have no equivalent in it. A garment made of one of those cannot be modelled, and it is withheld rather than mapped to something adjacent.

What this means for a catalogue

Three things are worth doing and one is worth not doing.

Put the composition in a structured field rather than only in the description. A description that happens to parse today stops parsing the moment somebody edits it for tone.

Use the legal fibre names. Elastane rather than spandex, polyamide rather than nylon, viscose rather than bamboo. Merchants write the informal names constantly and every one of them is a value a machine has to guess at.

Keep the qualifier separate from the name. Recycled polyester is a polyester percentage plus a recycled content claim, and the second one needs its own evidence.

The thing not to do is fill the field because it looks bad empty. A composition nobody has checked, sitting in a passport under a brand name, is a statement about a product that the brand is now making.

Where the values live and which of them a shop can already answer is covered in the Shopify guide.

The other twenty one fields Where composition sits in the set, and which fields are harder for everybody rather than only for small brands. Composition on a real passport row What a resolved value looks like in the artefact, next to the rows that stayed empty.

Sources