Fibre to Yarn

What you'll learn

• Types of natural fibres: silk, wool, cotton, jute.
• How silk is produced from silkworm (sericulture).
• How wool is obtained from animals (shearing, scouring, carding).
• Difference between natural and synthetic fibres.

Key concepts

What is a fibre?

• Fibre: thin, thread-like structure used to make yarn and then fabric.
• Yarn: long, continuous strand made by twisting fibres together (spinning).
• Fabric: woven or knitted material made from yarn.

Two main types of fibres:

Natural fibres from plants

Cotton:

• Obtained from cotton bolls (seed pods) of the cotton plant.
• Fibre is made of cellulose.
• Properties: soft, absorbs moisture, comfortable in heat.
• Cotton growing areas: warm, humid climate with well-drained soil.
• Process: picking cotton bolls → ginning (separating seeds from fibre) → spinning into yarn → weaving into fabric.

Jute:

• Obtained from the stem of the jute plant by retting (soaking in water to separate fibres).
• Strong, coarse fibre; used for sacks, ropes, bags, mats.
• Biodegradable — eco-friendly.
• Grown in hot, humid areas (West Bengal, Bangladesh).

Silk — sericulture

Sericulture: the rearing of silkworms (Bombyx mori) to produce raw silk.

Life cycle of silkworm:

1. Egg → laid by silk moth on mulberry leaves.
2. Larva (silkworm/caterpillar) → hatches from egg; feeds on mulberry leaves; grows through 4 moults.
3. Pupa (cocoon stage) → silkworm spins a continuous silk thread (up to 1500 m) around itself to form a cocoon; takes about 3 days.
4. Adult (silk moth) → emerges from cocoon.

Silk extraction:

1. Cocoons are boiled in hot water (to kill pupa and soften sericin that holds the thread).
2. Silk thread is reeled off the cocoon (single continuous thread).
3. Threads from several cocoons are twisted together → raw silk yarn.
4. Woven into fabric → silk cloth.

Properties of silk:

• Lustrous (shiny), smooth, soft.
• Lightweight yet strong.
• Absorbs moisture; comfortable in heat and cold.
• Expensive — labour intensive production.

Types of silk: Mulberry silk (most common), Tasar silk, Muga silk, Eri silk.

• Muga silk: golden-yellow silk from Assam; very rare.

Wool — from animals

Animals that give wool:

Process of getting wool from sheep:

1. Shearing: removing the fleece (wool coat) from the sheep with shears — done once a year in spring/summer; does not harm the sheep.
2. Scouring: washing the shorn wool in hot water with mild detergent to remove grease (lanolin), dirt and suint (dried sweat).
3. Sorting: separating wool by quality and fineness.
4. Carding: combing the fibres to straighten and align them.
5. Spinning: twisting the aligned fibres into yarn.
6. Weaving / Knitting: making wool fabric or woollen clothes.
7. Dyeing: colouring the wool yarn.

Properties of wool:

• Warm — traps air between fibres (air is a poor conductor of heat).
• Elastic — fibres are naturally crimped/curly.
• Absorbs moisture (up to 30%) without feeling wet.
• Fire-resistant (naturally contains nitrogen and sulphur).

Comparison: natural vs synthetic fibres

Quick check

• What is sericulture? Briefly outline the life cycle of a silkworm.
• How is silk thread obtained from a cocoon?
• What is shearing? Name three animals other than sheep that give wool.
• List the steps in processing wool from shearing to yarn.
• What is the difference between natural and synthetic fibres? Give two examples of each.

Open the Practice tab for graded questions on Fibre to Yarn.