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Material · Natural

Wool

Animal hair with scales and a permanent crimp — the fibre that insulates while wet, resists fire, and felts if you are careless with it.

Wool is keratin, the same protein as hair and horn, and its useful behaviour comes from two structural features. The fibre has overlapping scales along its surface, and it is permanently crimped rather than straight.

The crimp traps air, which is why wool insulates so well for its weight and why it keeps insulating when wet — an unusual property that made it the fibre of choice wherever people worked outdoors in the cold and rain. The scales are why wool felts: agitate it wet and the scales ratchet past one another and lock, irreversibly. That is a manufacturing process and a laundry disaster depending on whether it was intended.

Uses

Clothing, carpet, upholstery, insulation and felt. Wool carpet remains a premium product against polypropylene on resilience and on fire behaviour, and wool is naturally flame-resistant to a degree synthetics need additives to approach — it chars and self-extinguishes rather than melting, which is why it is specified for aircraft and rail interiors.

The sulfur in keratin is what gives burning wool its distinctive smell, and it is also why wool takes dye so readily: the protein offers chemical sites that cellulose and polyester do not.

History

The English wool trade financed a kingdom. Wool exports were the country's principal source of wealth and of tax revenue through the medieval period, the Lord Speaker of the House of Lords still sits on a woolsack, and the wealth is visible today in the disproportionately large parish churches of Suffolk and the Cotswolds.

The shift from exporting raw wool to exporting cloth, and later the enclosure of arable land for sheep, are among the more consequential economic transitions in English history — and among the more disruptive socially.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is used as

  • Textiles — application · clothing and carpet, where it insulates when wet and chars rather than melting — both properties synthetics need help to approach
  • Thermal insulation — application · the original, and still the reference for how a fibre traps still air

contains

  • Carbon — element · the protein backbone of keratin
  • Nitrogen — element · in the amide links — wool is a polyamide, which is the same linkage nylon uses
  • Sulfur — element · in the cross-links between keratin chains, which is what gives burning wool its smell and what holds the fibre's permanent crimp

is an alternative to

  • Polypropylene — material · in carpet, where wool holds a premium on resilience and on charring rather than melting

Sources

  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Material World
    Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Wool back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Downstream — what it becomes

  • Wool → is used as (clothing and carpet, where it insulates when wet and chars rather than melting — both properties synthetics need help to approach) → Textiles
  • Wool → is used as (the original, and still the reference for how a fibre traps still air) → Thermal insulation