Wool

Wool is a natural fibre obtained from certain animals. Wool comes from the **fleece** (hair) of animals such as sheep, goat, yak, camel, llama, and alpaca. These animals possess a thick coat of hair on their bodies.

This thick hair coat serves a crucial purpose: it traps a large amount of air. Air is a **poor conductor of heat**, meaning it does not transfer heat easily (a property you will learn about in Chapter 4). By trapping air, the hair acts as an insulating layer, keeping these animals warm in cold climates. The fibres that make up this hairy coat are used to produce wool.

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Activity 3.1

Comparing the texture of hair on different parts of your body (arms, head) helps understand the difference between coarse and fine hair, similar to the different types of hair found on sheep.

The hairy skin of a sheep typically has two types of fibres that form its fleece:

• **Coarse beard hair:** Rougher hairs.
• **Fine soft under-hair:** Denser, softer hairs located close to the skin. These fine hairs are the source of fibres used to make wool.

Some sheep breeds naturally have a higher proportion of this desirable soft under-hair. To produce breeds that yield only soft under-hair, parents with these specific desirable characteristics are intentionally chosen for breeding. This process is called **selective breeding**.

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Animals That Yield Wool

While wool commonly available in the market is sheep wool, several other animals also provide wool fibres:

• **Sheep:** Various breeds are reared in India for wool (see Table 3.1).
• **Yak:** Wool is common in Tibet and Ladakh.
• **Angora goats:** Found in hilly regions like Jammu and Kashmir, they yield **mohair** (a type of wool).
• **Goat:** The soft under fur of Kashmiri goats is used to make fine **Pashmina shawls**.
• **Camels:** The fur on their bodies is used as wool.
• **Llama and Alpaca:** Found in South America, these animals also yield wool.

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Activity 3.2

Collecting pictures of wool-yielding animals and finding their names in local or other Indian languages helps in identifying the diversity of these animals across regions.

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Activity 3.3

Mapping the geographical locations in India and the world where these wool-yielding animals are found helps visualize the distribution of wool production sources.

Table 3.1: Some Indian breeds of sheep and their wool quality/location (Example):

S.No.	Name of breed	Quality of wool	State where found
1.	Lohi	Good quality wool	Rajasthan, Punjab
2.	Rampur bushair	Brown fleece	Uttar Pradesh, Himachal Pradesh
3.	Nali	Carpet wool	Rajasthan, Haryana, Punjab
4.	Bakharwal	For woollen shawls	Jammu and Kashmir
5.	Marwari	Coarse wool	Gujarat
6.	Patanwadi	For hosiery	Gujarat

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From Fibres To Wool

To obtain wool fibres, sheep (or other wool-yielding animals) are reared and their hair is cut and processed. Rearing involves feeding and caring for the animals. Sheep are herbivores, primarily grazing on grass and leaves. Rearers also provide them with mixtures of pulses, grains, oil cakes, and minerals, especially during winter when they are kept indoors and fed on leaves, grain, and dry fodder.

Once the animals develop a thick coat of hair, it is removed to obtain wool fibres. This removal process is called shearing.

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Processing Fibres Into Wool

Converting the raw wool fibres obtained from shearing into finished woollen yarn involves several steps:

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Step I

**Shearing:** The fleece of the sheep, along with a thin layer of skin, is removed from the body. This is usually done during warm weather to allow the sheep to survive without their protective hair coat. Machines similar to barber's clippers are used for shearing. This process does not harm the sheep as the uppermost layer of skin is dead, similar to how a haircut doesn't hurt humans. The hair grows back.

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Step II

**Scouring:** The sheared skin with hair is thoroughly washed in tanks to remove grease, dust, and dirt. This cleaning process is called scouring. Nowadays, scouring is often done by machines.

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Step III

**Sorting:** After scouring, the hairy skin is sent to a factory where hairs of different textures are separated or sorted based on fineness, length, etc.

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Step IV

**Cleaning of Burrs:** Small fluffy fibres called burrs (the same ones sometimes seen on sweaters) are picked out from the sorted hair. The fibres are then scoured again and dried.

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Step V

**Dyeing:** The cleaned fibres are dyed in various colours, as the natural colour of fleece is typically black, brown, or white.

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Step VI

**Rolling into Yarn:** The dyed fibres are straightened, combed, and rolled into woollen yarn. Longer fibres are used to make wool for sweaters, while shorter fibres are spun and woven into woollen cloth.

The entire process from fibre to woollen yarn can be summarised as: Shearing $\rightarrow$ Scouring $\rightarrow$ Sorting $\rightarrow$ Cleaning of burrs $\rightarrow$ Dyeing $\rightarrow$ Rolling (into yarn).

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Occupational Hazard in Wool Industry:

The wool industry provides livelihood to many people. However, jobs like sorting wool carry risks. Sorters can get infected by a dangerous bacterium called **anthrax**, which causes a fatal blood disease known as **sorter's disease**. Risks faced by workers in an industry are termed **occupational hazards**.

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Activity 3.4

Debating the ethical aspects of rearing sheep and using their hair for wool encourages critical thinking about human use of animals.

Silk

**Silk** is another important animal fibre, produced by **silkworms**. The practice of rearing silkworms specifically for obtaining silk is called **sericulture**.

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Life History Of Silk Moth

Understanding the life cycle of the silk moth is essential to understand how silk is obtained. The typical life history of a silk moth involves several stages:

1. The female silk moth lays **eggs**.
2. From the eggs hatch **larvae**, which are called **caterpillars** or **silkworms**. These silkworms grow significantly in size.
3. Before entering the next stage (pupa), the caterpillar weaves a net around itself and then swings its head, secreting a fibre made of a **protein**.
4. This protein fibre hardens upon exposure to air, forming **silk fibre**. The caterpillar completely covers itself with this silk fibre.
5. This protective covering made of silk fibre is called the **cocoon**.
6. Inside the cocoon, the caterpillar transforms into the **pupa**.
7. The pupa develops into an **adult silk moth** inside the cocoon.
8. The adult moth then emerges from the cocoon, and the cycle continues.

The silk fibre used to make silk cloth is obtained from the **cocoon** spun by the silkworm. Silk yarn is known for its strength, comparable to a thread of steel of similar thickness.

Different varieties of silk moths produce different types of silk with varying textures (e.g., tassar silk, mooga silk, kosa silk), depending on the species of moth and the food they eat. The most common silk moth is the **mulberry silk moth**, whose cocoon yields soft, lustrous, and elastic silk that takes dye well.

Sericulture has a long history in India, and India is a significant producer of silk globally.

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Activity 3.5

Collecting and comparing different types of silk cloth (mulberry, tassar, eri, mooga) and artificial silk helps in understanding the variations in silk textures and distinguishing natural silk from synthetic fibres.

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Activity 3.6

Burning small samples of artificial silk, pure silk, and wool provides a way to differentiate them based on the smell produced during combustion. Pure silk and wool (both proteins) will smell similar to burning hair or feathers, while artificial silk (made from synthetic polymers) will smell like burning plastic.

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Activity 3.7

Arranging cut-out pictures of the silk moth life cycle stages in the correct order helps reinforce the understanding of the life history, from egg to adult moth and the crucial cocoon stage.

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From Cocoon To Silk

The process of obtaining silk fibres from cocoons is called **reeling**. First, silk moths are reared to produce cocoons. Farmers purchase silk moth eggs and raise the larvae (silkworms) under controlled, hygienic conditions with suitable temperature and humidity.

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Rearing Silkworms

Female silk moths lay hundreds of eggs. These eggs are stored and sold to farmers. When mulberry trees (the primary food source for mulberry silkworms) have fresh leaves, the eggs are warmed to hatch the larvae. The silkworms (caterpillars) feed continuously on mulberry leaves for about 25-30 days, growing significantly.

After this feeding period, the silkworms stop eating and move to a designated area (like small chambers or twigs in trays) to spin their cocoons. Inside the cocoon, they undergo the transformation into the pupa stage.

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Processing Silk

Once the cocoons are formed, they are collected. To obtain the silk fibre, the cocoons are usually exposed to heat (sunlight, boiling water, or steam). This heat kills the pupa inside and helps to separate the silk fibres from the cocoon.

The process of taking out the silk threads from the cocoon is called **reeling the silk**. Reeling is done using special machines that carefully unwind the continuous silk fibre from each cocoon.

These fine silk fibres are then spun into **silk threads**, which are finally woven by weavers into **silk cloth**.

Discovery of Silk:

According to a Chinese legend, silk was discovered by Empress Si-lung-Chi around 3000 BC when a silk moth cocoon fell into her cup of tea, and the delicate silk threads unravelled. China kept the production of silk a secret for hundreds of years before it spread to other parts of the world through trade routes (the famous 'Silk Road').

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