Class 7 Chapter 3 Fibre to Fabric Notes for Revision

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Fibre to Fabric Notes Class 7

Topics covered in this class 7 chapter 3 Fibre to Fabric Notes

  • Fibres and types of fibres
  • Natural Fibres
  • Fibre from Plants
  • Fibre to Animals
  • Processing of Wool
  • Silk
  • Health Hazards

Fibres

What are Fibres?

Fibres are the basic materials used for making clothes.

Fibres are obtained from plants and animals.

Types of Fibres0

If we talk about the types of fibres then there are mainly two types of fibres-

  1. Natural Fibre
  2. Synthetic Fibre or Artificial Fibre

Natural Fibre

These are the fibres that are obtained from natural sources like plants and animals.

Examples of Natural fibres are- Cotton, Jute, Wool, Silk, etc.

Synthetic Fibre or Artificial Fibres

Synthetic fibres are the fibres that are made by human beings with the help of chemicals.

Synthetic Fibres are fibres that are prepared by human beings through a number of processes using raw materials of petroleum origin, calld petrochemicals.

Some examples of Synthetic Fibres are: Nylon, Terylene, etc.

Note: You will read about synthetic fibres in class 8. Click here to read about synthetic fibres.

Semi-Synthetic Fibre

These are the types of fibres whose raw materials are both natural and synthetic.

Example- Rayon (The natural base material is wood pulp).

Wool

It is an animal fibre. Wool is present on the body of certain animals as a thick coat of hair.

What is Fleece?

This thick coat of hair on the body of the animals is called fleece.

  • Wool is obtained from animals like sheep, goat, yak, camel, rabbit, etc.
  • Wool traps air (a bad conductor of heat) and does not allow the heat to escape from the animals’ body. So, we wear woolen clothes in winter to keep our body warm.

Characteristics of Wool

  • It is a poor conductor of heat
  • Easily absorbs water
  • Durable and elastic
  • does not wrinkle easily

Here is the list of animals from where we obtain Wool

Goats

  • Cashmere wool obtained from Cashmere (Kashmiri) Goats are very fine and costly.
  • These variety of goats are also found in China, Mongolia, and Iran.
  • Wool obtained from Cashmere goats are used to make Pashmina Shawls.
  • Mohair (wool fibre) obtained from Angora goat is used to make clothes (younger goats) and carpets (old goats)

Rabbits

  • Angora wool obtained from Angora Rabbits are very soft, silky and fluffy.
  • The wools obtained are very light and warmer than the other types of wools.

Yaks

  • Wool obtained from Yaks are very warm and comfortable.
  • Yaks can be seen in Tibet, Nepal, China, Mongolia, and in Ladakh in India.

Camels

  • Wool is also obtained from camels.
  • Some breed of camels that yield good quality of wool are- Bactrian Camel, Alpaca, Llama, Vicuna
  • The two-humped Bactrian Camel is mainly found in Siberia, Mongolia, and China.
  • Alpaca and Llama is found in South America
  • Wool obtained from these are very soft, light and shiny.

Sheep

  • The wool obtained from sheep are commonly used by the masses. These are mainly used in India and Tibet.
  • The finest quality of wool obtained from Merino sheep from Spain.
  • There are tow types of hairs- coarse beard hair and fine under-hair close to the skin.
Rearing and Breeding Sheep

Define Rearing.

It is the process of raising and caring for sheep.

Breeding: It means to produce offspring.

What is Selective Breeding?

It is the process of obtaining desired characteristics in the offspring by selecting the parents of the desired characters.

This method of Selective Breeding is also called Artificial Selection.

Production of Wool from Sheep

After developing thick coat of hair, the hair is shaved off and goes through different processes to obtain Wool.

Following Steps are involved in the production of Wool

  1. Shearing
  2. Scouring
  3. Sorting
  4. Grading
  5. Dyeing
  6. Carding and Spinning
  7. Weaving and Knitting

Shearing

Shearing is the process of removing the fleece (thick coat of hair) of the sheep.

Shearing is done during the hot weather using machine or clippers.

Scouring

Scouring is the process where the dirt, dust and the grease is removed from the sheared fleece.

Sorting

It is the process of sorting or separating the hairs of different textures.

Grading

It is the process of grouping the the hair fibres based on their characteristics such as length, fineness, texture, colour,  etc.

Dyeing

Dyeing is the process in which the fibres obtained are dyed (coloured) to get a wide range of colours.

Carding and Spinning

Carding: Carding is the process done before spinning where the entangled fibres are straightened, combed by passing them through rollers having metal teeth.

Spinning is the process of twisting the fibres to get yarn.

Weaving and Knitting

To obtain fabric, the yarns are knitted or woven in machines or by hand.

Knitting uses single yarn, and Weaving uses more than one yarn.

For Knitting, longer fibres are suitable while for weaving shorter fibres are suitable.

Occupational Hazards in Wool Industry

Define Occupational Hazard.

Any risk of injury, disease or other health problem that a worker working in any industry may face.

Hazards faced by people working in the Wool Industry-

  • Anthrax disease : Also called Sorter’s disease
  • Skin Infection- from chemicals and dyes
  • Respiratory disease

Silk

It is the animal fibre obtained from the silkworms.

What are Silkworms?

These are the larvae (caterpillars) of silk moths.

What is Sericulture?

It is the rearing of silkworms for silk production.

Characteristics of Silk

  • it is shiny
  • very lightweight
  • strong and flexible
  • poor conductor of heat
  • elastic and crease resistant

Life Cycle of a Silk moth

Eggs → Larvae → Pupa → Cocoon → Moth

  • In the egg stage, female moth lays about 300 to 400 eggs and the eggs hatch in 7 to14 days.
  • After hatching, the larvae or the caterpillars feed on the leaves for 3-4 weeks and grow in size.

What is Moulting?

During the larval stage, the caterpillar sheds its skin four times and grow in size. This process is called moulting.

  • After the larval stage, the caterpillar stops feeding and starts to turn into a Pupa. In this pupal stage, the Pupa starts secreting a thin, continuous filament like substance from its two glands (salivary glands) on its head.
  • This substance made up of protein starts hardening on coming in contact with air. This hardened substance become silk fibre.
  • Cocoon: A protective covering made up of silk threads that a pupa makes by swinging its head side by side.
  • The pupa remain in the cocoon for about 15 days and then comes out of it as a grown adult moth.
  • This moth has a lifespan of about 3-10 days.

Types of Silk

  • Mulberry Silk
  • Tassar Silk
  • Kosa Silk
  • Mooga Silk
  • Eri Silk

Production of Silk from Silkworms

Following steps are involved in the production of silk from silkworms.

  1. Rearing
  2. Sorting
  3. Boiling of Cocoons or Degumming
  4. Reeling
  5. Dyeing
  6. Weaving

Occupational Hazards of the Silk Industry

  • Skin Infection
  • Respiratory Problems

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