Fibre and Fabric
Overview
Fibre and Fabric is a fundamental topic in the Science portion of Assam TET Paper II, bridging everyday life with scientific understanding. This topic tests your knowledge of how fibres are obtained, classified, and processed into fabrics that we use daily. Given Assam's unique position as India's leading producer of Muga silk and a significant producer of Eri and Pat silk, questions frequently centre on the state's silk varieties and sericulture practices.
For the exam, you must understand the distinction between natural and synthetic fibres, know the sources and properties of each type, and be familiar with the processing methods. Special attention should be given to Assam's three indigenous silk varieties—Muga, Eri, and Pat—as these hold cultural, economic, and scientific significance for the state. Expect 2–4 questions from this topic, often combining factual recall with application-based reasoning.
Mastery of this topic requires memorising key characteristics of fibres, understanding the silk production process (sericulture), and connecting traditional Assamese practices with modern textile science.
---
Key Concepts
- **Fibre vs Fabric**: A fibre is a thin, thread-like strand that is the basic unit of textiles. Fabric is made by weaving or knitting fibres together. Fibres are spun into yarn, which is then woven into fabric.
- **Classification of Fibres**: Fibres are broadly classified into natural fibres (obtained from plants or animals) and synthetic fibres (man-made from chemical processes).
- **Plant Fibres**: Cotton (from cotton bolls), jute (from stem), coir (from coconut husk), and flax (linen) are obtained from different plant parts and are cellulose-based.
- **Animal Fibres**: Wool (from sheep, goat, yak) and silk (from silkworm cocoons) are protein-based fibres obtained from animals.
- **Sericulture**: The rearing of silkworms for silk production. Assam practises sericulture for three distinct silk types, making it India's largest producer of Muga and Eri silk.
- **Synthetic Fibres**: Nylon, polyester, rayon, and acrylic are made from petrochemicals. They are strong, durable, and resistant to wrinkles and moths but are non-biodegradable.
- **Blended Fabrics**: Fabrics made by combining natural and synthetic fibres (e.g., polycotton) to achieve desired properties like durability and comfort.
- **Retting Process**: The process of soaking plant stems (jute, flax) in water to loosen fibres from the woody stem through bacterial action.
---
Formulas / Key Facts
| Fact | Detail | |------|--------| | **Muga Silk** | Golden-yellow silk from Antheraea assamensis; endemic to Assam; silkworm feeds on Som and Soalu trees; GI-tagged product | | **Eri Silk** | Creamy-white silk from Samia ricini; also called Ahimsa silk (cocoon not killed); silkworm feeds on castor leaves | | **Pat Silk** | Mulberry silk from Bombyx mori; white, lustrous; silkworm feeds on mulberry leaves | | **Cotton** | Obtained from seed hairs of cotton plant; India is second-largest producer globally | | **Jute** | Called "Golden Fibre"; obtained from stem; grown in Brahmaputra valley; biodegradable | | **Wool sources** | Sheep (most common), Angora goat (mohair), Kashmir goat (pashmina), yak | | **Nylon** | First fully synthetic fibre (1935); made from coal, water, and air; very strong | | **Polyester** | Most widely used synthetic fibre; made from petroleum; wrinkle-resistant | | **Rayon** | Semi-synthetic; made from wood pulp (cellulose); also called artificial silk | | **Silk protein** | Fibroin (forms the fibre) and sericin (gum coating the fibre) |
---
Worked Examples
**Example 1**: Classify the following fibres as natural or synthetic: Cotton, Nylon, Muga silk, Polyester, Jute, Acrylic.
*Solution*:
- Natural fibres (plant origin): Cotton, Jute
- Natural fibres (animal origin): Muga silk
- Synthetic fibres: Nylon, Polyester, Acrylic
---
**Example 2**: Why is Eri silk called "Ahimsa silk" or "peace silk"?
*Solution*: Eri silk is called Ahimsa silk because the silkworm is not killed during silk extraction. Unlike other silk types where cocoons are boiled with the pupa inside, Eri silk is obtained from open-ended cocoons. The moth emerges naturally, and the remaining cocoon is then spun into silk. This non-violent method aligns with the principle of ahimsa (non-violence).
---
**Example 3**: A student claims that rayon is a natural fibre because it comes from wood. Is this correct? Explain.
*Solution*: The student is incorrect. Although rayon is made from cellulose obtained from wood pulp (a natural source), it undergoes extensive chemical processing to convert it into fibre. Therefore, rayon is classified as a semi-synthetic or regenerated fibre, not a natural fibre. The raw material is natural, but the fibre itself is manufactured.
---
Common Mistakes
- **Confusing Muga with Pat silk** → Muga is golden-yellow and produced only in Assam from Antheraea assamensis feeding on Som/Soalu trees. Pat is white mulberry silk from Bombyx mori. Remember: Muga = golden = Assam exclusive.
- **Thinking rayon is fully natural** → Students assume wood pulp origin makes rayon natural. Correct understanding: Rayon is semi-synthetic because it requires chemical processing (viscose process) despite having a natural raw material.
- **Assuming all silk production kills silkworms** → Eri silk extraction does not kill the silkworm as moths emerge from open-ended cocoons before spinning. This is why it is called Ahimsa silk.
- **Mixing up fibre sources** → Jute comes from stem (bast fibre), cotton from seed, coir from fruit (coconut husk). Students often confuse which plant part yields which fibre.
- **Believing synthetic fibres are always better** → While synthetics are durable and cheap, they are non-biodegradable, cause pollution, melt on heating, and lack breathability. Natural fibres have their own advantages: comfort, biodegradability, and moisture absorption.
---
Quick Reference
- **Three silks of Assam**: Muga (golden, Som tree), Eri (white, castor, Ahimsa), Pat (white, mulberry)
- **Plant fibres = cellulose-based; Animal fibres = protein-based**
- **Retting** = soaking plant stems in water to extract fibres (jute, flax)
- **Nylon** = first synthetic fibre; **Rayon** = first semi-synthetic fibre (artificial silk)
- **GI tag**: Muga silk has Geographical Indication status—can only be called Muga if produced in Assam
- **Sericulture** = silkworm rearing; **Apiculture** = beekeeping (don't confuse!)