NCERT Textbook: Fibre to Fabric | General Science(Prelims) by IRS Divey Sethi - UPSC PDF Download

 Page 1


SCIENCE 24
Fibre to Fabric
3
I
n Class VI you have learnt about
some fibres obtained from plants.
You also learnt that wool and silk
fibres are obtained from animals. Wool
is obtained from the fleece  (hair) of
sheep or yak. Silk fibres come from
cocoons of the silk moth. Do you know
which part of the sheep’s body yields
fibres? Are you aware how these fibres
are converted into the woollen yarn that
we buy from the market to knit sweaters?
Do you have any idea how silk fibres are
made into silk, which is woven into saris?
In this Chapter we shall try to find
answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and
some other animals. These wool-yielding
animals bear hair on their body. Do you
know why these animals have a thick
coat of hair? Hair trap a lot of air. Air is
a poor conductor of heat, as you would
learn in Chapter 4. So, hair keeps these
animals warm. Wool is derived from
these hairy fibres.
Activity 3.1
Feel the hair on your body and arms
and those on your head. Do you find
any difference? Which one seems coarse
and which one is soft?
Like us, the hairy skin of the sheep
has two types of fibres that form its
fleece: (i) the coarse beard hair, and
(ii) the fine soft under-hair close to the
skin. The fine hair provide the fibres for
making wool. Some breeds of sheep
possess only fine under-hair. Their
parents are specially chosen to give birth
to sheep which have only soft under-
hair. This process of selecting parents
for obtaining special characters in their
offspring, such as soft under hair in
sheep, is termed ‘selective breeding’.
Fig. 3.1  Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in
different parts of our country (Table 3.1).
However, the fleece of sheep is not the
only source of wool, though wool
commonly available in the market is
2022-23
Page 2


SCIENCE 24
Fibre to Fabric
3
I
n Class VI you have learnt about
some fibres obtained from plants.
You also learnt that wool and silk
fibres are obtained from animals. Wool
is obtained from the fleece  (hair) of
sheep or yak. Silk fibres come from
cocoons of the silk moth. Do you know
which part of the sheep’s body yields
fibres? Are you aware how these fibres
are converted into the woollen yarn that
we buy from the market to knit sweaters?
Do you have any idea how silk fibres are
made into silk, which is woven into saris?
In this Chapter we shall try to find
answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and
some other animals. These wool-yielding
animals bear hair on their body. Do you
know why these animals have a thick
coat of hair? Hair trap a lot of air. Air is
a poor conductor of heat, as you would
learn in Chapter 4. So, hair keeps these
animals warm. Wool is derived from
these hairy fibres.
Activity 3.1
Feel the hair on your body and arms
and those on your head. Do you find
any difference? Which one seems coarse
and which one is soft?
Like us, the hairy skin of the sheep
has two types of fibres that form its
fleece: (i) the coarse beard hair, and
(ii) the fine soft under-hair close to the
skin. The fine hair provide the fibres for
making wool. Some breeds of sheep
possess only fine under-hair. Their
parents are specially chosen to give birth
to sheep which have only soft under-
hair. This process of selecting parents
for obtaining special characters in their
offspring, such as soft under hair in
sheep, is termed ‘selective breeding’.
Fig. 3.1  Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in
different parts of our country (Table 3.1).
However, the fleece of sheep is not the
only source of wool, though wool
commonly available in the market is
2022-23
FIBRE TO FABRIC 25
Fig. 3.6  Llama
sheep wool (Fig. 3.1). Yak (Fig. 3.2) wool
is common in Tibet and Ladakh. Mohair
is obtained from angora goats, (Fig. 3.3)
found in hilly regions such as Jammu
and Kashmir.
Wool is also obtained from goat hair
(Fig. 3.4). The under fur of Kashmiri
goat is soft. It is woven into fine shawls
called Pashmina shawls.
The fur (hair) on the body of camels
is also used as wool (Fig. 3.5). Llama
and Alpaca, found in South America,
also yield wool (Fig. 3.6 and 3.7).
Activity 3.2
Collect pictures of animals whose hair
is used as wool. Stick them in your scrap
book. If you are unable to get pictures,
try and draw them from the ones given
in this book.
Find out words for sheep, goat, camel
and yak in your local language and also
in other languages of our country.
Fig. 3.7  Alpaca
Fig. 3.2  Yak
Fig. 3.3  Angora goat Fig. 3.4  Goat
Fig. 3.5  Camel
Activity 3.3
Procure outline maps of India and the
world. Find out and mark the places on
the map where you find animals that
provide wool. Use different colours to
denote the location for different wool
yielding animals.
2022-23
Page 3


SCIENCE 24
Fibre to Fabric
3
I
n Class VI you have learnt about
some fibres obtained from plants.
You also learnt that wool and silk
fibres are obtained from animals. Wool
is obtained from the fleece  (hair) of
sheep or yak. Silk fibres come from
cocoons of the silk moth. Do you know
which part of the sheep’s body yields
fibres? Are you aware how these fibres
are converted into the woollen yarn that
we buy from the market to knit sweaters?
Do you have any idea how silk fibres are
made into silk, which is woven into saris?
In this Chapter we shall try to find
answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and
some other animals. These wool-yielding
animals bear hair on their body. Do you
know why these animals have a thick
coat of hair? Hair trap a lot of air. Air is
a poor conductor of heat, as you would
learn in Chapter 4. So, hair keeps these
animals warm. Wool is derived from
these hairy fibres.
Activity 3.1
Feel the hair on your body and arms
and those on your head. Do you find
any difference? Which one seems coarse
and which one is soft?
Like us, the hairy skin of the sheep
has two types of fibres that form its
fleece: (i) the coarse beard hair, and
(ii) the fine soft under-hair close to the
skin. The fine hair provide the fibres for
making wool. Some breeds of sheep
possess only fine under-hair. Their
parents are specially chosen to give birth
to sheep which have only soft under-
hair. This process of selecting parents
for obtaining special characters in their
offspring, such as soft under hair in
sheep, is termed ‘selective breeding’.
Fig. 3.1  Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in
different parts of our country (Table 3.1).
However, the fleece of sheep is not the
only source of wool, though wool
commonly available in the market is
2022-23
FIBRE TO FABRIC 25
Fig. 3.6  Llama
sheep wool (Fig. 3.1). Yak (Fig. 3.2) wool
is common in Tibet and Ladakh. Mohair
is obtained from angora goats, (Fig. 3.3)
found in hilly regions such as Jammu
and Kashmir.
Wool is also obtained from goat hair
(Fig. 3.4). The under fur of Kashmiri
goat is soft. It is woven into fine shawls
called Pashmina shawls.
The fur (hair) on the body of camels
is also used as wool (Fig. 3.5). Llama
and Alpaca, found in South America,
also yield wool (Fig. 3.6 and 3.7).
Activity 3.2
Collect pictures of animals whose hair
is used as wool. Stick them in your scrap
book. If you are unable to get pictures,
try and draw them from the ones given
in this book.
Find out words for sheep, goat, camel
and yak in your local language and also
in other languages of our country.
Fig. 3.7  Alpaca
Fig. 3.2  Yak
Fig. 3.3  Angora goat Fig. 3.4  Goat
Fig. 3.5  Camel
Activity 3.3
Procure outline maps of India and the
world. Find out and mark the places on
the map where you find animals that
provide wool. Use different colours to
denote the location for different wool
yielding animals.
2022-23
SCIENCE 26
From fibres to wool
For obtaining wool, sheep are reared.
Their hair is cut and processed into
wool. Let us learn about this process.
Rearing and breeding of sheep: If you
travel to the hills in Jammu & Kashmir,
Himachal Pradesh, Uttaranchal,
Arunachal Pradesh and Sikkim, or the
plains of Haryana, Punjab, Rajasthan
and Gujarat, you can see shepherds
taking their herds of sheep for grazing.
Sheep are herbivores and prefer grass
and leaves. Apart from grazing sheep,
rearers also feed them on a mixture of
pulses, corn, jowar, oil cakes (material
left after taking out oil from seeds) and
minerals. In winter, sheep are kept
indoors and fed on leaves, grain and dry
fodder.
Sheep are reared in many parts of
our country for wool. Table 3.1 gives the
names of some breeds of sheep reared
in our country for producing wool. The
quality and texture of the fibres obtained
from them is also indicated in the table.
Certain breeds of sheep have thick
coat of hair on their body which yields
good quality wool in large quantities. As
mentioned earlier, these sheep are
“selectively bred” with one parent being
a sheep of good breed.
Once the reared sheep have
developed a thick growth of hair, hair is
shaved off for getting wool.
Processing fibres into wool
The wool which is used for knitting
sweaters or for weaving shawls is the
finished product of a long process,
which involves the following steps:
Step I: The fleece of the sheep along with a
thin layer of skin is removed from its
body [Fig. 3.8 (a)]. This process is called
shearing. Machines similar to those used
by barbers are used to shave off hair.
Usually, hair are removed during the hot
weather. This enables sheep to survive
without their protective coat of hair. The
hair provide woollen fibres. Woollen
fibres are then processed to obtain
woollen yarn. Shearing does not hurt
the sheep just as it does not hurt when
you get a hair cut or your father shaves his
beard. Do you know why? The uppermost
layer of the skin is dead. Also, the hair of
sheep grow again just as your hair does.
Table 3.1 Some Indian breeds of sheep
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
2022-23
Page 4


SCIENCE 24
Fibre to Fabric
3
I
n Class VI you have learnt about
some fibres obtained from plants.
You also learnt that wool and silk
fibres are obtained from animals. Wool
is obtained from the fleece  (hair) of
sheep or yak. Silk fibres come from
cocoons of the silk moth. Do you know
which part of the sheep’s body yields
fibres? Are you aware how these fibres
are converted into the woollen yarn that
we buy from the market to knit sweaters?
Do you have any idea how silk fibres are
made into silk, which is woven into saris?
In this Chapter we shall try to find
answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and
some other animals. These wool-yielding
animals bear hair on their body. Do you
know why these animals have a thick
coat of hair? Hair trap a lot of air. Air is
a poor conductor of heat, as you would
learn in Chapter 4. So, hair keeps these
animals warm. Wool is derived from
these hairy fibres.
Activity 3.1
Feel the hair on your body and arms
and those on your head. Do you find
any difference? Which one seems coarse
and which one is soft?
Like us, the hairy skin of the sheep
has two types of fibres that form its
fleece: (i) the coarse beard hair, and
(ii) the fine soft under-hair close to the
skin. The fine hair provide the fibres for
making wool. Some breeds of sheep
possess only fine under-hair. Their
parents are specially chosen to give birth
to sheep which have only soft under-
hair. This process of selecting parents
for obtaining special characters in their
offspring, such as soft under hair in
sheep, is termed ‘selective breeding’.
Fig. 3.1  Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in
different parts of our country (Table 3.1).
However, the fleece of sheep is not the
only source of wool, though wool
commonly available in the market is
2022-23
FIBRE TO FABRIC 25
Fig. 3.6  Llama
sheep wool (Fig. 3.1). Yak (Fig. 3.2) wool
is common in Tibet and Ladakh. Mohair
is obtained from angora goats, (Fig. 3.3)
found in hilly regions such as Jammu
and Kashmir.
Wool is also obtained from goat hair
(Fig. 3.4). The under fur of Kashmiri
goat is soft. It is woven into fine shawls
called Pashmina shawls.
The fur (hair) on the body of camels
is also used as wool (Fig. 3.5). Llama
and Alpaca, found in South America,
also yield wool (Fig. 3.6 and 3.7).
Activity 3.2
Collect pictures of animals whose hair
is used as wool. Stick them in your scrap
book. If you are unable to get pictures,
try and draw them from the ones given
in this book.
Find out words for sheep, goat, camel
and yak in your local language and also
in other languages of our country.
Fig. 3.7  Alpaca
Fig. 3.2  Yak
Fig. 3.3  Angora goat Fig. 3.4  Goat
Fig. 3.5  Camel
Activity 3.3
Procure outline maps of India and the
world. Find out and mark the places on
the map where you find animals that
provide wool. Use different colours to
denote the location for different wool
yielding animals.
2022-23
SCIENCE 26
From fibres to wool
For obtaining wool, sheep are reared.
Their hair is cut and processed into
wool. Let us learn about this process.
Rearing and breeding of sheep: If you
travel to the hills in Jammu & Kashmir,
Himachal Pradesh, Uttaranchal,
Arunachal Pradesh and Sikkim, or the
plains of Haryana, Punjab, Rajasthan
and Gujarat, you can see shepherds
taking their herds of sheep for grazing.
Sheep are herbivores and prefer grass
and leaves. Apart from grazing sheep,
rearers also feed them on a mixture of
pulses, corn, jowar, oil cakes (material
left after taking out oil from seeds) and
minerals. In winter, sheep are kept
indoors and fed on leaves, grain and dry
fodder.
Sheep are reared in many parts of
our country for wool. Table 3.1 gives the
names of some breeds of sheep reared
in our country for producing wool. The
quality and texture of the fibres obtained
from them is also indicated in the table.
Certain breeds of sheep have thick
coat of hair on their body which yields
good quality wool in large quantities. As
mentioned earlier, these sheep are
“selectively bred” with one parent being
a sheep of good breed.
Once the reared sheep have
developed a thick growth of hair, hair is
shaved off for getting wool.
Processing fibres into wool
The wool which is used for knitting
sweaters or for weaving shawls is the
finished product of a long process,
which involves the following steps:
Step I: The fleece of the sheep along with a
thin layer of skin is removed from its
body [Fig. 3.8 (a)]. This process is called
shearing. Machines similar to those used
by barbers are used to shave off hair.
Usually, hair are removed during the hot
weather. This enables sheep to survive
without their protective coat of hair. The
hair provide woollen fibres. Woollen
fibres are then processed to obtain
woollen yarn. Shearing does not hurt
the sheep just as it does not hurt when
you get a hair cut or your father shaves his
beard. Do you know why? The uppermost
layer of the skin is dead. Also, the hair of
sheep grow again just as your hair does.
Table 3.1 Some Indian breeds of sheep
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
2022-23
FIBRE TO FABRIC 27
sometimes appear on your sweaters. The
fibres are scoured again and dried. This
is the wool ready to be drawn into fibres.
Step V: The fibres can be dyed in various
colours, as the natural fleece of sheep
and goats is black, brown or white.
Step VI: The fibres are straightened,
combed and rolled into yarn
[Fig. 3.8 (d)]. The longer fibres are
made into wool for sweaters and the
shorter fibres are spun and woven
into woollen cloth.
Step II: The sheared skin with hair is
thoroughly washed in tanks to remove
grease, dust and dirt. This is called
scouring. Nowadays scouring is done
by machines [Fig. 3.8 (b) and (c)].
Step III: After scouring, sorting is done.
The hairy skin is sent to a factory where
hair of different textures are separated
or sorted.
Step IV: The small fluffy fibres, called
burrs, are picked out from the hair.
These are the same burrs which
The processing of fibre into wool can be represented as follows:
Shearing ? Scouring ? Sorting ? Cleaning of burrs
             ?
 Rolling  ? Dyeing
Fig. 3.8  (d) Rolling into yarn
Fig. 3.8  (b) Scouring in tanks
Fig. 3.8  (c) Scouring by machines
Fig. 3.8  (a) Shearing a sheep
2022-23
Page 5


SCIENCE 24
Fibre to Fabric
3
I
n Class VI you have learnt about
some fibres obtained from plants.
You also learnt that wool and silk
fibres are obtained from animals. Wool
is obtained from the fleece  (hair) of
sheep or yak. Silk fibres come from
cocoons of the silk moth. Do you know
which part of the sheep’s body yields
fibres? Are you aware how these fibres
are converted into the woollen yarn that
we buy from the market to knit sweaters?
Do you have any idea how silk fibres are
made into silk, which is woven into saris?
In this Chapter we shall try to find
answers to these questions.
Animal fibres — wool and silk
3.1 WOOL
Wool comes from sheep, goat, yak and
some other animals. These wool-yielding
animals bear hair on their body. Do you
know why these animals have a thick
coat of hair? Hair trap a lot of air. Air is
a poor conductor of heat, as you would
learn in Chapter 4. So, hair keeps these
animals warm. Wool is derived from
these hairy fibres.
Activity 3.1
Feel the hair on your body and arms
and those on your head. Do you find
any difference? Which one seems coarse
and which one is soft?
Like us, the hairy skin of the sheep
has two types of fibres that form its
fleece: (i) the coarse beard hair, and
(ii) the fine soft under-hair close to the
skin. The fine hair provide the fibres for
making wool. Some breeds of sheep
possess only fine under-hair. Their
parents are specially chosen to give birth
to sheep which have only soft under-
hair. This process of selecting parents
for obtaining special characters in their
offspring, such as soft under hair in
sheep, is termed ‘selective breeding’.
Fig. 3.1  Sheep with thick growth of hair
Animals that yield wool
Several breeds of sheep are found in
different parts of our country (Table 3.1).
However, the fleece of sheep is not the
only source of wool, though wool
commonly available in the market is
2022-23
FIBRE TO FABRIC 25
Fig. 3.6  Llama
sheep wool (Fig. 3.1). Yak (Fig. 3.2) wool
is common in Tibet and Ladakh. Mohair
is obtained from angora goats, (Fig. 3.3)
found in hilly regions such as Jammu
and Kashmir.
Wool is also obtained from goat hair
(Fig. 3.4). The under fur of Kashmiri
goat is soft. It is woven into fine shawls
called Pashmina shawls.
The fur (hair) on the body of camels
is also used as wool (Fig. 3.5). Llama
and Alpaca, found in South America,
also yield wool (Fig. 3.6 and 3.7).
Activity 3.2
Collect pictures of animals whose hair
is used as wool. Stick them in your scrap
book. If you are unable to get pictures,
try and draw them from the ones given
in this book.
Find out words for sheep, goat, camel
and yak in your local language and also
in other languages of our country.
Fig. 3.7  Alpaca
Fig. 3.2  Yak
Fig. 3.3  Angora goat Fig. 3.4  Goat
Fig. 3.5  Camel
Activity 3.3
Procure outline maps of India and the
world. Find out and mark the places on
the map where you find animals that
provide wool. Use different colours to
denote the location for different wool
yielding animals.
2022-23
SCIENCE 26
From fibres to wool
For obtaining wool, sheep are reared.
Their hair is cut and processed into
wool. Let us learn about this process.
Rearing and breeding of sheep: If you
travel to the hills in Jammu & Kashmir,
Himachal Pradesh, Uttaranchal,
Arunachal Pradesh and Sikkim, or the
plains of Haryana, Punjab, Rajasthan
and Gujarat, you can see shepherds
taking their herds of sheep for grazing.
Sheep are herbivores and prefer grass
and leaves. Apart from grazing sheep,
rearers also feed them on a mixture of
pulses, corn, jowar, oil cakes (material
left after taking out oil from seeds) and
minerals. In winter, sheep are kept
indoors and fed on leaves, grain and dry
fodder.
Sheep are reared in many parts of
our country for wool. Table 3.1 gives the
names of some breeds of sheep reared
in our country for producing wool. The
quality and texture of the fibres obtained
from them is also indicated in the table.
Certain breeds of sheep have thick
coat of hair on their body which yields
good quality wool in large quantities. As
mentioned earlier, these sheep are
“selectively bred” with one parent being
a sheep of good breed.
Once the reared sheep have
developed a thick growth of hair, hair is
shaved off for getting wool.
Processing fibres into wool
The wool which is used for knitting
sweaters or for weaving shawls is the
finished product of a long process,
which involves the following steps:
Step I: The fleece of the sheep along with a
thin layer of skin is removed from its
body [Fig. 3.8 (a)]. This process is called
shearing. Machines similar to those used
by barbers are used to shave off hair.
Usually, hair are removed during the hot
weather. This enables sheep to survive
without their protective coat of hair. The
hair provide woollen fibres. Woollen
fibres are then processed to obtain
woollen yarn. Shearing does not hurt
the sheep just as it does not hurt when
you get a hair cut or your father shaves his
beard. Do you know why? The uppermost
layer of the skin is dead. Also, the hair of
sheep grow again just as your hair does.
Table 3.1 Some Indian breeds of sheep
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
2022-23
FIBRE TO FABRIC 27
sometimes appear on your sweaters. The
fibres are scoured again and dried. This
is the wool ready to be drawn into fibres.
Step V: The fibres can be dyed in various
colours, as the natural fleece of sheep
and goats is black, brown or white.
Step VI: The fibres are straightened,
combed and rolled into yarn
[Fig. 3.8 (d)]. The longer fibres are
made into wool for sweaters and the
shorter fibres are spun and woven
into woollen cloth.
Step II: The sheared skin with hair is
thoroughly washed in tanks to remove
grease, dust and dirt. This is called
scouring. Nowadays scouring is done
by machines [Fig. 3.8 (b) and (c)].
Step III: After scouring, sorting is done.
The hairy skin is sent to a factory where
hair of different textures are separated
or sorted.
Step IV: The small fluffy fibres, called
burrs, are picked out from the hair.
These are the same burrs which
The processing of fibre into wool can be represented as follows:
Shearing ? Scouring ? Sorting ? Cleaning of burrs
             ?
 Rolling  ? Dyeing
Fig. 3.8  (d) Rolling into yarn
Fig. 3.8  (b) Scouring in tanks
Fig. 3.8  (c) Scouring by machines
Fig. 3.8  (a) Shearing a sheep
2022-23
SCIENCE 28
Activity 3.4
Debate amongst your classmates
whether it is fair on the part of humans
to rear sheep and then chop off their
hair for getting wool.
3.2 SILK
Silk fibres are also animal fibres.
Silkworms spin the ‘silk fibres’. The
rearing of silkworms for obtaining silk
is called sericulture. Find out from
your mother/aunt/grandmother the
kind of silk saris they have. List the
kinds of silk.
Before we discuss the process of
obtaining silk, it is necessary to know the
interesting life history of the silk moth.
Life history of silk moth
The female silk moth lays eggs, from
which hatch larvae which are called
caterpillars or silkworms. They grow in
size and when the caterpillar is ready to
enter the next stage of its life history
called pupa, it first weaves a net to hold
itself. Then it swings its head from side
to side in the form of the figure of eight (8).
During these movements of the head,
the caterpillar secretes fibre made of a
Occupational hazard
Wool industry is an important
means of livelihood for many people
in our country. But sorter’s job is
risky as sometimes they get infected
by a bacterium, anthrax, which
causes a fatal blood disease called
sorter’s disease. Such risks faced by
workers in any industry are called
occupational hazards.
Boojho is wondering why a
cotton garment cannot keep us
as warm in winter as a woollen
sweater does.
Boojho is wondering why it
hurts when someone pulls his
hair but not when he goes for a
haircut.
(a) Male            (b) Female
Adult silk moths
(c) Eggs on mulberry leaves             (d) Silkworm
 (e) Cocoon (f) Cocoon with developing moth
Fig. 3.9  (a to f) Life history of silk moth
2022-23