Manufactured fibres - synthetic (polyester, nylon/polyamide, elastane/Lycra, acrylic) and regenerated (viscose): their origin, characteristic properties, and how those properties make them suitable for particular fashion and textile items, including the reasons for blending fibres.

What this key area is asking

Most modern garments are not pure natural fibre; they use manufactured fibres, either alone or blended with natural fibres. SQA Higher expects you to know how these fibres are made, their characteristic properties, the items they suit, and the reasons fibres are blended. As with natural fibres, the marks are won by linking a property to a use, and by explaining why a blend gives a better fabric than either fibre alone.

How manufactured fibres are made

Because the fibre is extruded, manufacturers can control its thickness, length and cross-section, which is why manufactured fibres are so consistent and can be engineered for particular properties.

Synthetic fibres

Polyester

Polyester is strong, crease-resistant, quick-drying, holds its shape, is cheap and is thermoplastic (it can be heat-set to fix pleats). Its weakness is that it is not absorbent (so it can feel clammy and hold odours) and it melts and shrinks from heat rather than burning cleanly. It is the most widely blended fibre, used in shirts, trousers, school uniform, curtains and fillings.

Nylon (polyamide)

Nylon is very strong, elastic, abrasion-resistant and lightweight, which makes it ideal for items that take heavy wear: hosiery, sportswear, swimwear, rucksacks, ropes and umbrellas. Like polyester it is not absorbent and is thermoplastic, and it can be damaged by sunlight over time.

Elastane (Lycra)

Elastane has exceptional elasticity and recovery, stretching several times its length and springing back. It is used in small percentages (often 2 to 5 per cent) to add stretch and a close, comfortable fit to leggings, sportswear, swimwear, jeans and underwear.

Acrylic

Acrylic is soft, warm and lightweight, a cheaper substitute for wool, used in knitwear, fleece, blankets and soft toys. It is easy-care and resists moths, but it is not very absorbent, can pill, and is highly flammable, so it is unsuitable for nightwear.

Regenerated fibres

Viscose (rayon) is the main regenerated fibre, made from cellulose (wood pulp) that is chemically dissolved and reformed. It is soft, absorbent, cool and drapes well, with a silk-like handle, so it suits linings, dresses, blouses and soft furnishings. Its weaknesses are that it is weak when wet, creases and can shrink, so it is often blended or finished. (Modal and lyocell/Tencel are stronger, more sustainable developments of viscose.)

Why fibres are blended

Examples in context

Example 1. Sports leggings in nylon and elastane. Leggings are made from nylon with a small percentage of elastane because nylon is strong, lightweight and abrasion-resistant and elastane gives stretch and recovery, so the leggings move with the body, resist wear and hold their shape, which is why this blend dominates activewear.

Example 2. A lining in viscose. A jacket lining is made from viscose because it is smooth, cool and drapes well, so it slips on easily and hangs neatly inside the jacket. Because a lining is not heavily stressed or often washed, viscose's weakness when wet matters little, which is why it is a common, economical lining choice.

Try this

Q1. State the origin of viscose and one property that makes it suitable for a summer dress. [2 marks]

• Cue. Viscose is regenerated from cellulose (wood pulp); it is soft, cool and drapes well, so a summer dress feels comfortable and hangs attractively.

Q2. Explain two reasons a manufacturer might blend acrylic with wool for a jumper. [4 marks]

• Cue. Acrylic lowers the cost of an expensive pure-wool jumper; it adds easy-care, machine-washable behaviour and reduces shrinking and felting; it keeps the jumper soft and warm while wool provides warmth and resilience. Develop any two.