[Chemistry Class Notes] on Wool Pdf for Exam

Wool is a kind of fibre obtained from hairs of sheep, goat, yak, and some other animals. From the definition, it is clear that wool can be obtained from many animals, not only from sheep. The clothes that we wear are cotton, silk, nylon, and wool. These fabrics are obtained from the fibres. These are naturally available to us or are man-made. The basic unit of any kind of fabric is fibre. Let’s discuss the fibre in more detail.

Types of Fibre

On the basis of origin, fibre can be divided into two types:

1. Natural Fibres

The origin of this fibre is natural. It can be further classified into various types:

• Plant fibres

• Animal fibres

• Mineral fibres

2. Man-Made Fibre 

These are synthetic fibres. These fibres can be further classified into a different subgroup:

• Regenerated fibres

• Synthetic fibres

• Metallic fibres

Let’s discuss the Main Fibres

This is the type of fibre that are obtained from plants. For example- cotton and flax.

This type of fibre is obtained from animals. For example- silk and wool.

This type of fibres are manufactured in industries. These are called man-made fibres. For example- nylon, polyester.

Types of Wool

Sheep wool is obtained from sheep and it is commonly used and famous in Tibet and Ladakh. Angora wool is obtained from angora goat and it is commonly used in the hilly region like Jammu and Kashmir. The underfur of the angora goat is used in making fine shawls known as pashmina shawls. 

The fur of many other animals is used in making fibre like a camel. Fur or camel, alpaca, llama etc is used in making fibre. In India the famous and common source of wool is sheep.

The quality and the quantity of the wool depends on the breed of the sheep. Some breeds of sheep have fine hair while others have coarse hairs.

Types of Sheep Hair

There are two forms of sheep hair present:

1. Coarse beard Hair

2. The Fine Soft under Hair Close to the Skin

Wool is obtained from this type of sheep hair. This type of hair is very fine. Therefore, used in making wool fibres. We see that sheep are the main source of wool. We need to produce good quality wool-producing sheep. For this, we perform selective breeding.

What is selective breeding? Selective breeding is the process of selecting parents for obtaining special characters in their offspring. So, for obtaining wool we need sheep with more soft hairs and less coarse hairs. In the Manufacturing process of wool, the selective parents will be the sheep with soft fine under hairs.

The Manufacturing Process of Wool

The manufacturing process of wool involves four steps. These steps are given below:

• Shearing

• Scouring

• Sorting

• Fabric production

Let’s Discuss Each Step One by One

1. Shearing

It is done manually by using a pair of scissors or electrically driven shavers. In this process when hairs are removed from the live sheep, known as clipped wool. When it is obtained from dead sheep it is known as pulled wool.

2. Scouring

The sheared skin with hairs is thoroughly washed in large tanks to remove grease, dirt, and dust. This process is known as souring.

3. Sorting 

The hairy skin is sent to industries where hairs with various textures are separated or sorted. The small fluffy fibres are called burrs. These burrs are picked out from the hair. The people involved in this process generally get infected by the bacteria called Bacillus anthracis. This disease is called sorter’s disease. 

Flowchart of the Manufacturing Process of Wool

• The fur or the skin of the sheep (generally sheep)

• Shearing (removal of thin dead skin layer)

• Scouring (removed skin is washed in a large industrial tank to remove grease, oil, dirt and other kinds of contaminants.)

• Sorting (hair of various texture is separated)

• Removal of burrs (small fluffy fibres)

• Dyeing of the processed wool (adding different colours)

• Rolling into yarn

Parameters for measuring Quality of Wool

The quality of wool can be analysed using the following criteria.

• The thickness of the fibre- The thinner the fibre, the better the quality of the wool is.

• Waviness- A wool of good quality is more crimpy than inferior wool.

• Fibre length- the good quality of wool has a short fibre length. 

Uses of Wool

• Wool is used in weaving sweaters.

• Wool has been used for making carpets.

• Wool is used in making wool felt. These are used for absorbing noises coming from heavy machines and stereo speakers.

Did You Know?

• Wool has the ability to absorb moisture.

• Wool does not burn over the flame but smoulders.

• Wool is a lightweight fabric.

• We do not need to iron wool regularly as wool does not wrinkle easily.

• Wool fabrics are resistant to dirt.