From Fibre to Fabric - Class 7 Notes & Olympiad Questions

From Fibre to Fabric

a) Fibres are like tiny, flexible threads that can be found in different materials. They can be really thin and are important for making fabrics.
b) These fibres are spun together to create yarn, which is like a long, continuous thread. This yarn is then used to make different types of fabrics that we use for clothes, blankets, and other things.
c) So basically, fibres are turned into yarn, and yarn is used to make fabrics that we use every day.

Types of Fibres

a) There are indeed two main types of fibres: natural fibres and synthetic fibres.
b) Both natural and synthetic fibres are extensively used in the textile industry to create a wide range of fabrics, clothing, home textiles, and other products.
c) The choice between natural and synthetic fibres depends on factors such as desired properties, cost, sustainability, and personal preferences.

Natural Fibres

a) Natural fibres are derived from plants or animals. They have been used for thousands of years and are obtained from natural sources.
b) Examples of natural fibres include cotton, wool, silk, linen, jute, and hemp. Each natural fibre has unique properties and characteristics.
c) For instance, cotton is soft and breathable, wool provides insulation and warmth, silk is smooth and lustrous, and jute is durable and strong.

Synthetic Fibres

a) Synthetic fibres, also known as artificial fibres, are man-made and produced through chemical processes.
b) They are created from raw materials derived from petroleum or other chemicals. Synthetic fibres offer various advantages such as strength, durability, and versatility.
c) Common examples of synthetic fibres include polyester, nylon, acrylic, rayon, and spandex. These fibres can be engineered to possess specific properties like moisture-wicking, elasticity, or resistance to wrinkles.

Types of Natural Fibres

1. Plant Fibres

Source: Plant fibres are obtained from various parts of plants, such as the stem, leaves, seeds, or fruit.

Examples: Common plant fibres include cotton (from cotton plant seeds), flax (from the stem of the flax plant), jute (from the stem of the jute plant), and bamboo (from the pulp of bamboo plants).

Characteristics: Plant fibres tend to be softer and more breathable compared to animal fibres. They can offer varying degrees of strength, durability, moisture-wicking properties, and absorbency depending on the specific plant fibre.

Common Uses: Plant fibres are widely used in the production of clothing, bed linens, towels, sacks, ropes, carpets, and other textiles and products.

2. Animal Fibres

Source: Animal fibres are obtained from animals through shearing, combing, or other methods. They can come from different animals, including sheep, silkworms, goats, rabbits, and alpacas.

Examples: Common animal fibres include wool (from sheep), silk (from silkworms), cashmere (from goats), angora (from rabbits), and mohair (from goats).

Characteristics: Animal fibres are known for their warmth, softness, and insulation properties. They often have a luxurious feel and can be highly durable. Animal fibres can vary in texture, thickness, and other qualities depending on the animal and specific fibre.

Common Uses: Animal fibres are primarily used in the production of clothing, accessories (such as scarves and hats), blankets, upholstery, and other high-quality textiles.

Wool

Wool is indeed obtained from the fleece, which is the coat of hair, of animals like sheep, goats, yaks, and others. The fleece acts as an insulating covering over the animal's body, protecting them from the cold during winter.

When it comes to sheep, their fleece consists of two types of fibres:

Coarse Beard Hair: This type of fibre is the outer, coarser hair found in the fleece. It provides strength and durability to the wool.

Fine and Soft Under Hair: This fibre grows close to the animal's skin and is softer and finer in texture. It provides insulation and helps in trapping air, which adds to the warmth and softness of the wool.

Properties of Wool

Wool is widely used in the textile industry for making warm clothing, blankets, carpets, and other products due to its excellent insulation, durability, and other desirable properties.

1. Poor Conductor of Heat: Wool is a poor conductor of heat, which means it helps to keep the body warm by trapping air and preventing heat loss.

2. Biodegradable and Fire Resistant: Wool is a natural fibre and is biodegradable, meaning it can break down naturally over time. It also has inherent fire-resistant properties, as it tends to burn slowly and is self-extinguishing.

3. Durability and Flexibility: Woollen fibres are known for their durability, making them long-lasting and resistant to wear and tear. They also have natural flexibility, allowing them to stretch and recover without losing their shape easily.

4. Odour and Burning: When wool burns, it gives off a distinct smell of burning hair due to its composition. Additionally, wool has a tendency to burn slowly, making it less prone to catching fire.

Process of Obtaining Wool from Animal Hair Fibres

The process of obtaining wool from the hair fibre of animals, such as sheep, involves several steps.

Step 1: Shearing

a) Shearing is the process of removing the fleece or coat of hair from the sheep.
b) It is usually done during the hot season to prevent the sheep from feeling cold.
c) A skilled person, called a shearer, uses special shearing tools to carefully remove the fleece along with a thin layer of the sheep's skin.

Step 2: Scouring

a) After shearing, the sheared hair, known as raw wool, contains dirt, dust, grease, and other impurities.
b) The raw wool goes through a process called scouring, which involves washing it in tubs filled with soapy water. This helps to remove the dirt and grease from the wool fibres.

Step 3: Sorting

a) Once the wool is clean, it undergoes sorting, where the fibres are separated based on their texture and quality.
b) Skilled workers carefully examine and separate the wool fibres according to their colour, length, and fineness.

Step 4: Removing Burrs

a) During the sorting process, any burrs or soft, fluffy fibres present in the wool are manually removed.
b) Burrs are small, prickly seeds or plant matter that may have become entangled in the wool. The cleaned wool is then further processed and dried.

Step 5: Dyeing (Optional)

The natural colour of the sheep's wool may be white, black, brown, or other shades. If desired, the wool fibres can be dyed into different colours using specific dyes. This step adds variety and allows for a range of coloured wool.

Step 6: Making Yarn

a) The prepared wool fibres are straightened out, combed, and aligned to ensure evenness and smoothness. This process is called carding or combing.
b) The carded or combed wool fibres are then spun into yarn, which involves twisting the fibres together to create a continuous thread-like material.
c) The yarn can be further processed through knitting or weaving to create fabrics, clothing, or other woollen products.

By following these steps, the wool fibres obtained from animals like sheep are transformed into usable yarn, which is then used in various textile applications.

Occupational Hazards in the Wool Industry

1. Wool Sorter’s Disease

a) In the wool industry, people involved in tasks like sorting or handling wool may come into contact with a bacterium called anthrax. This bacterium can cause a serious illness known as anthrax infection or Sorter’s disease.
b) If someone working in the wool industry inhales or comes into contact with anthrax spores, it can lead to the development of sorter's disease. This disease can have severe symptoms and, in rare cases, can be fatal.
c) To prevent the risks of anthrax infection, safety precautions and measures are taken in the wool industry. These may include wearing protective clothing, using proper ventilation in work areas, practising good hygiene, and following guidelines for handling and processing wool to minimize exposure to the bacterium.

2. Dust and Allergies

a) Working with wool can generate a significant amount of dust, which may contain wool fibres, dirt, and other particles.
b) Inhaling this dust over a prolonged period can lead to respiratory issues and allergies, particularly for those who are sensitive or have pre-existing respiratory conditions.

3. Chemical Exposure

a) Some chemicals are used in the processing of wool, such as dyes, detergents, and pesticides.
b) Workers who handle these chemicals directly or work in areas where they are used may be at risk of skin irritation, allergic reactions, or other health issues if they are not properly protected or if they come into direct contact with these substances.

Silk

Silk is a natural fibre that is produced by silkworms, particularly the larvae of silkworm moths. When silkworms enter the pupa stage of their life cycle, they spin a protective cocoon made of silk fibres. These fibres are harvested and processed to create silk fabric.

Properties of Silk

Silk is highly valued for its luxurious feel, natural sheen, and unique properties. It is used in various applications, including clothing, bedding, upholstery, and accessories. Its exquisite qualities make it a sought-after material in the fashion and textile industry.

Lustrous Appearance: Silk has a natural shimmer and lustre that gives it a luxurious and elegant look. This quality makes silk a popular choice for clothing and textiles.

Lightweight and Water Absorbent: Silk is known for its lightweight nature, which makes it comfortable to wear. It can also absorb moisture without feeling damp, making it a breathable fabric that helps regulate body temperature.

Poor Conductor of Heat: Silk has low thermal conductivity, meaning it does not readily transfer heat. This property allows the silk to keep you cool in hot weather and retain warmth in colder temperatures.

Strength: Silk is considered one of the strongest natural fibres. Despite its delicate and smooth texture, silk is remarkably durable and has good tensile strength, which means it can withstand pulling and stretching without tearing easily.

Burning Odor: When silk is burned, it emits a distinctive smell similar to burning hair. This can be used as an identification method to distinguish silk from other fabrics.

Life Cycle of A Silk Moth

a) The life cycle of a silk moth represents a fascinating process of growth, transformation, and reproduction.
b) It is this life cycle that forms the basis of silk production, as the cocoons are carefully harvested before the adult moths emerge.
c) The silk fibres within the cocoon are unravelled to create silk thread, which is then used to produce various silk products.

Stage 1: Egg laying

The female silk moth lays eggs, usually on the leaves of the mulberry tree. The eggs are small and can be observed as tiny specks.

Stage 2: Larva (Caterpillar)

a) The eggs hatch within a week, and the larvae emerge. These larvae are commonly known as silkworms or caterpillars.
b) They feed voraciously on mulberry leaves, their primary source of food. As they consume the leaves, they grow in size.

Stage 3: Cocoon Formation

a) When the caterpillar is fully grown, it begins the process of cocoon formation. It secretes a silk fibre made of proteins through a pair of specialized glands called spinnerets located near its mouth.
b) The caterpillar uses its head to swing in a figure-eight motion while producing this silk fibre. The silk fibre is initially in a liquid state but hardens upon exposure to air.
c) The caterpillar wraps itself in this silk fibre, forming a protective structure called a cocoon. Inside the cocoon, the caterpillar undergoes a transformation into a pupa.

Stage 4: Pupa

a) The pupa is a stage of metamorphosis where the transformation from caterpillar to adult moth occurs.
b) Inside the cocoon, the pupa develops and undergoes significant changes. This stage typically lasts for a few weeks, during which the pupa grows and matures.

Stage 5: Adult Moth

a) After completing its development within the cocoon, the adult silk moth emerges by breaking open the cocoon.
b) The moth carefully pushes its way out and unfolds its wings, which are initially soft and wrinkled.
c) Once its wings expand and dry, the moth is ready to fly. The adult silk moth's primary purpose is to reproduce and lay eggs, starting the life cycle anew.

Production of Silk

Silk production involves a process called sericulture, which includes breeding and raising silkworms to obtain silk. Some steps involved in the process are:

Step 1: Rearing Silkworms to Obtain Cocoons

a) Female silk moths lay hundreds of eggs, and these eggs are kept warm to encourage hatching.
b) Once the eggs hatch, the larvae, also known as caterpillars or silkworms, are placed in trays made of bamboo.
c) They are provided with freshly-chopped mulberry leaves, which they feed on for about 25 to 30 days. During this time, they grow and prepare to enter the next stage.

Step 2: Processing Cocoons to Obtain Silk Fibre

a) After the feeding period, the caterpillars begin spinning a cocoon around themselves to protect their transformation into adult moths.
b) The cocoons are carefully collected. To obtain the silk fibres, the cocoons undergo a process called reeling.
c) This typically involves boiling the cocoons or using heat treatment to kill the pupa inside.
d) Once the pupa is no longer alive, the silk fibres can be unwound from the cocoon.

Step 3: Converting Silk Fibre into Silk Cloth

a) The silk fibres obtained from the cocoons are spun together to create silk yarn.
b) This spinning process involves twisting the fibres together to form continuous threads or yarns.
c) The silk yarn is then given to skilled weavers who use various looms or machines to weave the yarn into silk cloth.
d) Weaving involves interlacing the threads vertically (warp) and horizontally (weft) to create the fabric.

Occupational Hazards Associated with Silk Production

1. Inhalation Hazards

a) During the process of steaming, cooking, and reeling the cocoons, vapours may be released.
b) These vapours can cause respiratory issues such as breathing problems, asthma, and other bronchial ailments if inhaled by workers who are exposed to them for prolonged periods.

2. Skin Irritation

a) Workers involved in the silk production process may have to dip their hands and feet in boiling water to kill the silkworms inside the cocoons.
b) This constant exposure to hot water can lead to skin irritation, causing the skin to become raw and blistered.

It's important for employers in the silk industry to implement proper safety measures and provide protective equipment to minimise these risks. This can include using proper ventilation systems to reduce vapour exposure, providing protective clothing and gloves to prevent skin contact with boiling water, and educating workers about the potential hazards and how to protect themselves.

Synthetic Fibres

Polyester

a) Polyester is a widely used synthetic fibre known for its durability, resistance to wrinkles, and quick-drying properties.
b) It is derived from petroleum, a non-renewable resource.
c) Polyester fibres are used in various applications, including clothing, home textiles, upholstery, and outdoor fabrics.

Nylon

a) Nylon is a strong and resilient synthetic fibre known for its high tensile strength. It is derived from petroleum as well.
b) Nylon fibres find applications in stockings, athletic wear, swimwear, and outdoor gear.

Acrylic

a) Acrylic is a synthetic fibre that resembles wool in its softness and warmth.
b) It is derived from chemicals derived from petroleum or natural gas.
c) Acrylic fibres are used in making sweaters, blankets, hats, and other winter garments.

Rayon

a) Rayon is a semi-synthetic fibre made from regenerated cellulose, which is derived from wood pulp or other plant-based materials.
b) It is considered a "natural-based" synthetic fibre.
c) Rayon fibres have various applications in clothing, upholstery, and bedding.

Spandex

a) Spandex, also known as Lycra or elastane, is a stretchable synthetic fibre that provides elasticity and shape retention to fabrics.
b) It is derived from petrochemicals.
c) Spandex is commonly blended with other fibres to add stretch and comfort to clothing items such as leggings, swimwear, and sportswear.

Burning Characteristics of Fibres