Natural fibres: cotton, linen, wool and silk

1Why this matters

An afternoon in Bugesera or Nyagatare can be hot, while an early morning in Musanze or Nyabihu can be cold enough for a jumper. Choosing the right fibre for the weather, the job and the budget is one of the most practical skills in Home Science.

This lesson describes the four main natural fibres: where each comes from, its characteristics (the properties that make it behave as it does), what it is used for, and how to care for it.

2Cotton

Cotton grows as soft white fibres attached to the seeds inside the boll, the seed pod of the cotton plant. After picking, the fibres are separated from the seeds, cleaned and spun.

• Characteristics: soft and comfortable; very absorbent, so it takes up sweat and feels cool; strong, and even stronger when wet; withstands a hot iron and hot washing; creases easily; may shrink unless pre-shrunk; burns easily.
• Uses: shirts, kitenge, T-shirts, towels, bedsheets, underwear.
• Care: washes well in warm or hot water; white cotton can be bleached; iron hot while slightly damp.

3Linen

Linen comes from the stem of the flax plant. The long fibres inside the stem are separated from the woody parts and spun.

• Characteristics: the strongest of the plant fibres; very absorbent and dries quickly, so it feels cool; smooth with a slight natural shine, often with small thick places called slubs; creases very badly; withstands the hottest iron.
• Uses: tablecloths, tea towels, summer suits and dresses.
• Care: wash in warm water; iron hot while damp to remove the creases.

4Wool

Wool is the fleece of sheep, cut off once a year by shearing, then washed and spun. It is a protein fibre.

• Characteristics: warm, because its wavy (crimped) fibres trap air, which insulates; elastic and springy, so it resists creasing and keeps its shape; absorbs moisture without feeling wet; weaker when wet; shrinks and felts (the fibres lock together) with heat, rubbing and strong soap; damaged by alkalis such as bleach; eaten by moth larvae; burns slowly and tends to go out by itself.
• Uses: jumpers and school pullovers, blankets, suits, carpets.
• Care: hand-wash in lukewarm water with a mild detergent; squeeze, do not rub or wring; dry flat in the shade; press with a warm iron over a damp cloth.

5Silk

Silk is a long filament spun by the silkworm, the caterpillar of the silk moth, to build its cocoon. The cocoons are softened in hot water and the filament is unwound. Silk is a protein fibre.

• Characteristics: smooth, with a natural shine (lustre); strong for how fine it is; light, and hangs in soft folds (it drapes well); absorbent; warm in cool weather; weakened by strong sunlight, sweat and bleach; expensive.
• Uses: scarves, ties, formal dresses, linings.
• Care: hand-wash gently in lukewarm water with a mild detergent, or dry-clean; dry away from direct sun; iron with a cool iron.

6Comparing the four

Worked example: choosing a fibre

(a) A school shirt for hot days in Nyagatare. The shirt must take up sweat and let the body cool. Cotton is absorbent, cool and washes well in hot water, so cotton, or a blend with a high share of cotton, is the best choice.

(b) A pullover for cold mornings in Musanze. The pullover must hold in body heat. Wool traps air between its crimped fibres, so it insulates, and it stays warm even when a little damp from mist.

(c) A tablecloth for a family restaurant. It will be washed hot and often and must look fresh. Linen or cotton: both are strong, absorbent and take a hot wash and a hot iron. Linen is stronger and has a smart shine but costs more and creases more; cotton is the cheaper choice.

Practice

Solution. (a) The seed pod (boll): cotton fibres grow on the seeds. (b) The stem of the flax plant.

Solution. It will shrink and felt. Heat, rubbing and strong alkaline soap make the scales on wool fibres lock together, so the pullover becomes smaller, thicker and stiff, and the change cannot be undone.

Solution. Cotton absorbs sweat and lets it evaporate, which cools the skin, and it does not trap much air. Wool's crimped fibres trap a layer of air that holds heat in.

Solution. Any two of: it is expensive; it is weakened by sweat and strong sunlight; it needs gentle hand-washing or dry-cleaning rather than frequent hard washing; it is damaged by bleach.