Fibre, yarn and fabric
A fibre is a fine, flexible strand, at least about 100 times longer than it is wide. Short fibres (cotton, wool) are called staple fibres; very long ones (silk, synthetic filaments) are filaments.
Fibres → spun into yarn → yarns woven (two sets crossing at right angles) or knitted (loops) into fabric. Some fabrics, like felt, are made straight from fibres (non-woven).
Classification: natural and manufactured fibres
- Natural – plant (cellulose): cotton (seed hair of the cotton plant), linen (stem of the flax plant), jute, hemp.
- Natural – animal (protein): wool (sheep fleece), silk (cocoon thread of the silkworm), also goat hair like cashmere.
- Manufactured – regenerated: natural cellulose from wood pulp is dissolved and pushed through a spinneret to make new fibres: viscose rayon, lyocell, modal.
- Manufactured – synthetic: polymers made from oil chemicals: nylon (polyamide), polyester, acrylic, elastane (spandex).
Fibre shapes and properties
What a fibre looks like under a microscope explains how it behaves:
- Cotton: flat, twisted ribbon. Absorbent, cool, strong (stronger wet), creases easily, can shrink.
- Linen: straight rod with "nodes". Very strong, cool, lustrous, creases badly.
- Wool: crimped with overlapping scales. Crimp traps air → warm and springy; scales lock together with heat and rubbing → felting and shrinkage.
- Silk: smooth, triangular in cross-section → shiny (lustrous), soft, strong for its weight.
- Viscose: striated rod. Absorbent and soft like cotton, but weak when wet.
- Nylon and polyester: smooth, round rods. Very strong, elastic, crease-resistant, quick-drying, low absorbency (can feel sweaty), melt with heat.
- Acrylic: bean or dog-bone shape. Warm and light like wool, cheap, can pill.
Key properties to compare: absorbency, strength, warmth, elasticity, crease resistance, flammability, cost and environmental impact.
Spinning fibres into yarns and blends
Spinning: fibres are cleaned, combed or carded (lined up), drawn out into a thin strand and twisted. Twist holds the fibres together by friction: more twist gives a stronger, harder yarn; less twist gives a softer, fluffier yarn. Synthetic filaments are made by pushing melted or dissolved polymer through a spinneret (a plate with tiny holes) and then stretching.
Two or more fibres can be blended in one yarn. Polycotton (polyester + cotton) is absorbent and comfortable but stronger and less creasing; wool + nylon socks are warm and hard-wearing; adding a little elastane gives stretch.
Testing and investigating fibres
Burn test (only with an adult, a small sample held in tweezers over a metal tray): cellulose fibres burn fast with a paper smell and soft ash; protein fibres smell of burnt hair and leave crushable ash; synthetics melt, shrink away from the flame and leave a hard bead.
Other tests: look under a microscope; drop water on the fabric and time how fast it soaks in (absorbency); crush it in your hand and see if creases stay (crease recovery); hang weights until a yarn breaks (strength). Make tests fair: same sample size, same conditions, repeat and average.
Sustainability: cotton needs a lot of water; synthetics come from oil and shed microplastics; recycled polyester and organic cotton reduce harm.
Try it
In the 3D, pick cotton and then polyester and compare their absorbency and crease-resistance bars. At home: cut a small square from an old cotton cloth and an old polyester cloth. Put one drop of water on each and count the seconds until it soaks in. Which is better for a towel? Why?
Key formulas and definitions
- Fibre → yarn (spinning) → fabric (weaving or knitting)
- Natural: plant (cellulose) – cotton, linen; animal (protein) – wool, silk
- Manufactured: regenerated (viscose, lyocell) and synthetic (nylon, polyester, acrylic, elastane)
- More twist → stronger, firmer yarn
- Blend = two or more fibres in one yarn to combine properties
- Burn test: paper smell = cellulose; burnt hair = protein; melts to bead = synthetic
Worked examples
1. Which fibre would you choose for a summer shirt in a hot, humid city, and why?
Cotton or linen: they absorb sweat, let heat escape and feel cool. Polyester absorbs little and would feel sticky.
2. A wool jumper shrank after a hot wash. Explain.
Wool fibres have scales. Heat, water and rubbing make the scales lock together (felting), so the fibres pull closer and the jumper shrinks.
3. A sample melts, shrinks from the flame and leaves a hard bead. What group is it?
A synthetic fibre such as nylon, polyester or acrylic.
4. Why is viscose called a regenerated fibre, not a synthetic one?
It is made from natural cellulose (wood pulp) that is dissolved and re-formed into fibres; synthetics are made from polymers built from oil chemicals.
5. Why is a polycotton blend popular for school uniforms?
Cotton gives comfort and absorbency; polyester adds strength, quick drying and crease resistance, so the uniform lasts and needs less ironing.
Common mistakes
- Calling viscose a natural fibre; it is manufactured (regenerated) from natural cellulose.
- Thinking synthetic means weak; nylon and polyester are among the strongest fibres.
- Mixing up fibre, yarn and fabric.
- Doing a burn test with a large sample or without an adult and safety tray.