Natural fibres (cotton, linen, wool, silk): their origin, characteristic properties (absorbency, strength, warmth, crease resistance, durability, flammability), and how those properties make them suitable or unsuitable for particular fashion and textile items.

What this key area is asking

A fibre is the basic building block of every fabric, and its properties are decided largely by what it is made of. SQA Higher expects you to know the origin of the main natural fibres, their characteristic properties, and, most importantly, how those properties make a fibre suitable or unsuitable for a particular fashion or textile item. The marks at Higher are won by linking a property to a use, not by listing properties on their own.

Where natural fibres come from

• Cotton is a cellulosic fibre from the seed head (boll) of the cotton plant.
• Linen is a cellulosic fibre from the stem of the flax plant (a bast fibre).
• Wool is a protein fibre from the fleece of sheep (specialty wools come from goats, alpacas and so on).
• Silk is a protein fibre from the cocoon spun by the silkworm; it is the only natural fibre that comes as a continuous filament.

The properties that matter

Higher questions test a small set of properties, because these are the ones that decide whether a fabric performs in use:

• Absorbency - how much moisture the fibre takes up; high absorbency feels comfortable against the skin but is slow to dry.
• Warmth (insulation) - how well the fibre traps air and holds heat.
• Strength and durability - how hard-wearing the fibre is, and whether it weakens when wet.
• Crease resistance - whether the fabric springs back or holds creases.
• Flammability - how readily the fibre burns, which matters for safety items.
• Handle and appearance - softness, lustre and drape.

The four main natural fibres

Cotton

Cotton is highly absorbent, cool, soft and strong (and stronger when wet), and it washes well at high temperatures, which is why it is used for items worn next to the skin and washed often: T-shirts, underwear, bedding and towelling. Its weakness is that it creases easily and can shrink, and it burns readily, so it is often blended with polyester or given an easy-care finish.

Linen

Linen is the strongest and coolest of the natural fibres and very absorbent, with a crisp handle, so it is prized for summer suits, jackets, dresses and table linen. Its major drawback is that it creases very badly, so it is often blended or finished to improve crease resistance.

Wool

Wool is warm because its crimped fibres trap air, it is naturally crease-resistant and flame-resistant (it tends to smoulder and self-extinguish rather than flare), and it can absorb up to about a third of its weight in moisture while still feeling warm and dry. This makes it ideal for jumpers, coats, suits, blankets and carpets. Its weaknesses are that it can shrink and felt if washed incorrectly, is weaker when wet, and can feel itchy, so it needs careful (often hand or wool-cycle) washing.

Silk

Silk is strong, smooth, has a natural lustre, drapes beautifully and is warm for its light weight, so it is used for luxury blouses, ties, scarves, lingerie and evening wear. Its weaknesses are that it is expensive, weakens when wet, is damaged by sunlight and perspiration, and needs gentle care.

Examples in context

Example 1. Bed linen in cotton. Sheets are chosen in cotton because it is absorbent (comfortable against the skin overnight), cool, strong and washes at high temperatures for hygiene. The crease tendency matters little for bedding, so cotton's main drawback is not a problem here, which is why it dominates the bedding market.

Example 2. A summer jacket in linen. A lightweight summer jacket is made in linen because it is the coolest and most absorbent natural fibre, keeping the wearer comfortable in heat. The fabric will crease, but a relaxed summer jacket is expected to look slightly crumpled, so the property that would rule linen out elsewhere is acceptable for this product.

Try this

Q1. State the origin of wool and one property that makes it suitable for a winter coat. [2 marks]

• Cue. Wool comes from the fleece of sheep (a protein fibre); it is warm because its crimped fibres trap air, which insulates the wearer.

Q2. Explain two reasons silk is suitable for an evening blouse. [4 marks]

• Cue. Silk has a natural lustre and smooth handle, giving a luxurious appearance suited to evening wear; it drapes well, so the blouse hangs and moves attractively; it is warm for its light weight, so it is comfortable. Develop any two.