Textiles II: Fibres – JSS3 Home Economics Lesson Note (Second Term)

Fibres are the basic units spun into yarns and woven into fabrics.

• Natural fibres: come from plants or animals.
• Man-made fibres: come from cellulose-based or non-cellulose-based materials.
• This note covers: the properties, manufacture and identification tests of cotton, linen, wool, silk, viscose rayon, acetate and nylon.

Behavioural objectives

1. State the two main classes of fibres and give examples of each.
2. State the properties of cotton, linen, wool, silk, viscose rayon, acetate and nylon.
3. List the steps in the manufacture of cotton, linen, wool and rayon.
4. Describe the appearance, microscopic and burning tests used to identify different fibres.

What are the key terms used in fibres?

These terms are used throughout the topic.

• Fibre: a thin strand that is the basic unit of a textile.
• Yarn: fibres twisted together into a continuous thread.
• Fabric: cloth made by weaving yarns together.
• Filament: a very long, continuous fibre, such as silk or rayon.
• Cotton linters: the short fibres left clinging to cotton seeds after ginning.
• Spinneret: a nozzle with many fine holes, used to form man-made filaments.

What are the classes of fibres?

Fibres are classified into two main classes: natural fibres and man-made fibres.

What are the properties of common fibres?

Each fibre has its own source and properties, and these decide how the fabric is used and cared for.

What are the properties of cotton?

Cotton is a vegetable fibre made from the bolls of the cotton plant, where the fibres surround the seeds.

• Absorbent: it takes in moisture quickly.
• Strong: it is reasonably strong and durable.
• Washable: it washes well.
• Easy to dye: it takes dye easily.
• Comfortable: it is cool to wear.

What are the properties of linen?

Linen is a vegetable fibre obtained from the stem of the flax plant.

• Source: flax grows in countries such as France and Russia.
• Strong: it is stronger than cotton.
• Absorbent: it takes in moisture and is cool to wear.
• Slow drying: it dries slowly.
• Washable: it washes well.
• Heat conductor: it is a good conductor of heat, so it feels cool.

What are the properties of wool?

Wool is an animal fibre obtained from the fleece of sheep.

• Other sources: the hair of the camel, Angora rabbit or Angora goat can also be used.
• Producers: wool is commonly produced in Britain, Australia and other countries.
• Scaly surface: a wool fibre has a scaly appearance.
• Strength: it is stronger when dry than when wet.
• Burning smell: it gives the smell of burning feathers when burnt.
• Absorbent: it makes very absorbent fabrics.
• Bleach: it is readily damaged by bleach.

What are the properties of silk?

Silk is an animal fibre produced by silkworms.

• Producers: silk is produced chiefly in France, Italy, China and Japan.
• Strong: it is a very strong fibre.
• Fine: it is smooth and fine.
• Warm: it is warm to touch.
• Absorbent: it absorbs moisture easily.
• Costly: it is an expensive fibre.

What are the properties of viscose rayon?

Viscose rayon is a man-made fibre made by treating wood pulp or cotton linters with certain chemicals.

• Weak when wet: it is not very strong, especially when wet.
• Smooth: it has a smooth surface.
• Silk-like look: it resembles silk in appearance only.

What are the properties of acetate?

Acetate is a man-made fibre made from wood pulp or cotton linters treated with acetic acid and acetic anhydride.

• Quick drying: it dries quickly.
• Weak when wet: it loses strength when wet.
• Drape: it is silk-like and drapes well.

What are the properties of nylon?

Nylon is the family name for all synthetic polyamides.

• Strong: it is very strong.
• Light: it is light in weight.
• Easy care: it requires no ironing.
• Durable: it lasts a long time.

How are fibres manufactured?

Each fibre goes through its own series of steps before it becomes yarn and fabric.

How is cotton processed?

Cotton is processed from the boll to fabric in nine steps.

1. Ginning: the fibres are separated from the seeds.
2. Baling: the fibre is pressed into large bundles called bales.
3. Clearing: dirt and leaf bits are removed.
4. Carding: the fibres are brushed so that they lie in the same direction.
5. Combing: short fibres are removed to leave smooth, even fibres.
6. Drawing: the fibres are stretched into an even rope.
7. Spinning: the fibres are twisted into yarn.
8. Dyeing: the yarn is coloured.
9. Weaving: the yarns are woven into fabric.

How is linen produced?

Linen is produced from the stem of the flax plant in four steps.

1. Retting: the stems are soaked so that the material binding the fibres rots away.
2. Breaking and scutching: the woody part of the stem is crushed and scraped off.
3. Combing: the fibres are combed and separated.
4. Spinning: the fibres are twisted into yarn.

How is wool processed?

Wool fibres are made into two forms of yarn: worsted yarn and woollen yarn.

• Worsted yarn: made from long fibres, and it is smooth and firm.
• Woollen yarn: made from short fibres, and it is fuzzy and soft.

The major steps in the manufacture of both forms are:

1. Clipping: the fleece is cut from the sheep.
2. Sorting: the fleece is graded by quality.
3. Scouring: the wool is washed to remove grease and dirt.
4. Carbonising: plant matter caught in the wool is removed with chemicals.
5. Carding: the fibres are brushed into line.
6. Spinning: the fibres are twisted into yarn.
7. Weaving: the yarns are woven into fabric.

How is rayon made?

Rayon is made by changing cellulose into a liquid and forcing it through a spinneret to form filaments.

1. The cellulose (wood pulp or cotton linters) is first purified.
2. The cellulose is treated with the right chemicals and changed into a thin liquid.
3. The liquid is forced through a spinneret, which is a nozzle with many fine holes. Rayon filaments are formed.
4. The filaments are spun into yarns.
5. The yarns are woven into fabric.

How do we test different fibres?

Fibres are identified by their appearance, by their look under a microscope and by how they burn.

How is the burning test done?

1. Take a small piece of the fabric or a few threads.
2. Hold it with tongs or forceps. Do this with the teacher present.
3. Bring it slowly towards a flame, then into the flame.
4. Watch how it burns, and whether it melts or shrinks away.
5. Smell the smoke carefully after the flame is removed.
6. Look at the ash or residue left behind.

What do the tests show for each fibre?

Evaluation

1. Name the two main classes of fibres and give two examples of each.
2. State three properties of cotton.
3. List the steps in the manufacture of linen from the flax plant.
4. What is the difference between worsted yarn and woollen yarn?
5. How do cotton and wool behave when burnt?

Assignment

Draw a table to compare cotton and nylon under three headings: source, properties and burning test.