Fibre to Fabric: Class 7 Science NCERT Chapter 3
Key Features of NCERT Material for Class 7 Science Chapter 3 – Fibre to Fabric
In the last chapter 2, you learned about Nutrition in Animals. In this chapter, we have to learn about Fibre to Fabric.
Quick revision notes
Fibres are flimsy, string like strands from which textures (or fabrics) are made. A few instances of filaments are cotton, wool, silk, flax, jute, nylon, polyester and polyacrylic. The Fibres are spun into yarn (long consistent string) which would then be able to be woven on a loom to make a texture (or material). Sweet potato is a sort of since quite a while ago, curved string. Yarn is produced using strands by the way toward turning.
There are two sorts of strands, for example characteristic fiber and man-made fiber (nylon, rayon). A portion of our garments are produced using yarn got from the creature fiber. These are the sorts of common filaments as they are acquired from nature. Common strands are the filaments which are acquired from regular sources like plants and creatures.
In Class VI, we have found out about certain filaments got from plants. In this part, we will learn about certain filaments acquired from creatures. Wool and silk filaments are gotten from creatures. Wool is acquired from the downy (hair) of sheep or yak and silk filaments originate from casings of the silk moth.
Wool
The wool originates from creatures like sheep, goat, yak, camel, llama and alpaca. The wool yielding creatures bear a thick layer of hair on their body. The hair which gives us wool and keeps them warm during the virus winter season. The hair (wool) on the assortment of wool-yielding creatures trap a ton of air. Air spaces between the wool strands trap air. Since the air is a helpless conductor of warmth. Thus, the air caught in hair shields the body from cold and keeps them warm in winter.
The hair near our skin, for example hair on our body and arms are delicate and the hair on our head is coarse hair. Like us, the bristly skin of sheep has two kinds of strands that structure its downy (or wool), for example
- the coarse whiskers hair and
- the fine delicate under-hair near the skin.
The fine delicate under-hair give the fiber to making wool. To acquire types of sheep that have just fine under hair, their folks are deliberately picked. This cycle of choosing guardians for getting uncommon characters in their posterity, for example, delicate under hair in sheep is named as particular rearing. Such sheep give better nature of wool as well as the yield per sheep is likewise higher.
Some Indian types of sheep which give wool
| Name of a type of sheep | Nature of wool | Name of the state where found |
| Lohi | Great quality wool | Rajasthan, Punjab |
| Rampur bushier | Earthy colored wool | Uttar Pradesh, Himachal Pradesh |
| Nali | Rug wool | Rajasthan, Haryana, Punjab |
| Bakharwal | For woolen cloaks | Jammu and Kashmir |
Raising and Breeding of Sheep
Raising of sheep intends to take care of the sheep by giving them feed (food), asylum and medical services. The people who take care of the sheep (or rearers) are called shepherds. Sheep are herbivores and like to eat grass and leaves. Thus, shepherds take their groups of sheep to the field for munching. Aside from brushing, sheep rearers likewise feed them a blend of heartbeats, corn, jowar, oil cakes (material forgot about subsequent to taking oil from seeds) and minerals. In winter, sheep are kept inside and benefited from leaves, grain and dry grub.
Thus, the rearing of sheep is done to get such types of sheep which yield great nature of wool in enormous amounts. These types of sheep have a thick layer of hair on their body and are called sheep of good varieties. This raises the quality and amount of wool delivered.
Once, the raised sheep have built up a thick layer of hair, the hair is shaved off for getting wool. The cut off ‘wool layer’ of a sheep (alongside a dainty layer of skin) is called downy. The downy comprises of delicate woolen strands. The wool of sheep is generally kept in one piece.
Silk
Silk is a characteristic fiber which is gotten from a bug (called silk moth). Thus, silk strands are likewise creature filaments. Silkworms turn the silk filaments. The silk fiber is comprised of a protein. Silk is the most grounded characteristic fiber.
Sericulture
Sericulture signifies ‘silk cultivating’. The raising of silkworms for acquiring silk is called sericulture. Sericulture is an extremely old occupation in India. India creates a great deal of silk on a business scale. Before we talk about the way toward acquiring silk, it is important to know the intriguing life history of the silk moth.
Unadulterated and Artificial Silk
Unadulterated silk is acquired from the covers of silkworm and it is comprised of protein. Fake silk is acquired from wood mash and it is made of adjusted plant material ‘cellulose’. Much the same as silk, wool is additionally comprised of proteins. Along these lines, a bit of woolen texture additionally consumes giving the smell of consuming hair. The string which consumes giving a smell of consuming paper will be cotton filaments. Cotton and paper both are starches. Paper is made of cellulose acquired from wood mash. In this way, on consuming cotton and paper both give comparable smell.
From Cocoon to Silk
For getting silk, silk moths are raised and their cases are gathered to get silk string.
Raising Silkworms
A female silk moth lays hundred of eggs one after another. The eggs are put away cautiously on portions of paper or fabric and offered to silkworm ranchers. The ranchers hold eggs under sterile condition. They warm them to a reasonable temperature for the hatchlings to incubate from egg.
The hatchlings are kept in clean bamboo plate alongside youthful and newly hacked mulberry leaves. Following 25-30 days, the silkworms quit eating and begin turning the cases. Little racks or twigs might be given in the plate to which cases get connected.
Handling Silk
The cases are gathered and bubbled in water to slaughter the bug inside them. The subsequent fiber is known as crude silk. The silk strands separate out.
Reeling the Silk
The way toward taking out filaments from the casing for use as silk is known as reeling the silk. Reeling is done in exceptional machines. Silk filaments are spun into silk strings which are woven into silk fabric by weavers.