Wool Fibre: Types, Characteristics, Microscopic Structure and Uses

What is Wool Fibre?
Wool fibre is a natural protein fibre obtained from the fleece of sheep or other animals, such as goats, alpacas, and rabbits. It is expensive and very desirable in protective and hygiene applications because of its wide-ranging properties. It also can absorb a large amount of moisture. Therefore, it can be considered as a potential alternative to cellulose fibres to some extent. It is the sustainable material available for cloth nappy materials because it is breathable, naturally bacteriostatic, and does not require special care to maintain its shape and water-resistant properties.

wool fibre
Figure 1: Wool fibre

Wool fibre is a naturally curly, elastic, and insulating material that is commonly used in the manufacture of clothing, blankets, and upholstery. The fibres are made up of keratin, the same protein found in human hair and nails. Wool fibers have a unique structure that provides them with excellent insulating properties, making them warm in cold weather and cool in hot weather.

Wool hair has some special characteristics such as crimp, elasticity, special texture and handle. It is a staple fibre and has typical scales on its surface. This phenomenon, together with crimp, gives clinging power to wool and makes it hold on to the other neighbouring fibres. The crimp varies with fibre fineness. The finest ‘Merino’ wool may have even 100 crimps per inch (around 40 crimps/cm) whereas very coarse may hardly have 2–4 crimps per inch. Wool is hygroscopic in nature and can absorb up to one-third of its weight without feeling wet. The fibres also absorb sound. It is generally creamy white but in some instances, brownish fibres are also seen.

Types of Wool Fibre:
There are several types of wool fibre, which vary in texture, length, and crimp:

  1. Merino wool: Merino wool is fine, soft, and crimpy, making it ideal for clothing that is worn next to the skin, such as underwear and base layers.
  2. Cashmere wool: Cashmere wool is incredibly soft and has a fine texture, making it ideal for luxury clothing and accessories.
  3. Romney wool: This wool is coarser and has a longer staple length than Merino wool, making it ideal for outdoor clothing and blankets.
  4. Shetland wool: Shetland wool is fine and soft, with a crimp that is not as pronounced as Merino wool. It is ideal for delicate, lightweight clothing and accessories.
  5. Border Leicester wool: It is a long-stapled, coarser wool that is ideal for outerwear, rugs, and carpets.
  6. Corriedale wool: Corriedale wool is a versatile wool that is coarser than Merino wool but softer than Romney wool. It is ideal for a wide range of clothing and accessories.
  7. Lincoln wool: This wool fiber is a long-stapled, coarser wool that is ideal for outerwear, rugs, and carpets.
  8. Alpaca wool: It is soft, lightweight, and has excellent insulating properties. It is ideal for clothing and accessories that need to be warm and lightweight.

Properties / Characteristics of Wool Fibre:
Wool fibre has several unique properties that make it a versatile and desirable material for clothing and textiles. It is comfortable, warm, durable, and safe, and its natural properties make it an ideal choice for people with sensitive skin and for those who are environmentally conscious.

These properties include:

a) Crimp: Wool has a natural crimp, or wave-like structure, that gives them their elasticity and makes them well-suited for insulation. The crimp helps to distribute stress evenly, which reduces the risk of tearing and breaking.

b) Softness: They are naturally soft, making them comfortable to wear next to the skin. The softness of wool fibres varies depending on the breed of sheep, but in general, wool fibres are much softer than other animal fibres, such as horsehair or mohair.

c) Moisture Absorption: Wool fibres have a natural ability to absorb moisture, which helps keep the skin dry and comfortable.

d) Insulating Properties: The crimped structure of wool fibres provides excellent insulation, making it a warm material in cold weather and cool in hot weather.

e) Elasticity: Wool fibres have a natural elasticity, meaning they can stretch and return to their original shape. This makes wool clothing comfortable to wear and helps it retain its shape over time.

f) Flame Resistance: Wool has a natural resistance to fire, making them a safe choice for clothing and textiles.

g) Durability: Wool fibres are strong and durable, making them ideal for use in clothing and textiles that are subject to wear and tear.

h) Hypoallergenic: These fibres are hypoallergenic, meaning they are unlikely to cause an allergic reaction in most people. For this properties wool a good choice for clothing and textiles for people with sensitive skin.

i) Biodegradability: Wool fibres are biodegradable, meaning they can break down naturally in the environment. This makes wool an environmentally friendly material that is not harmful to the environment.

Microscopic Structure of Wool Fibre:
The microscopic structure of wool fibre consists of three main components, the cuticle, cortex and medulla. Cortex is the outer layer of cells that contains most of the fibre’s fibres and is responsible for its strength and elasticity, and a medulla, which is a less densely packed central core. The cortex is surrounded by overlapping scales, which run along the length of the fibre and help to protect it from wear and tear.

The complex morphological structure of fine wool fibres is shown schematically in Figure 2. Fine wools contain two types of cell: the cells of the external cuticle and those of the internal cortex. Together, these constitute the major part of the mass of clean wool.

Schematic diagram of the morphological components of a fine wool fibre
Figure 2: Schematic diagram of the morphological components of a fine wool fibre

Uses of Wool Fibre:
Wool fibre is known for its unique properties, making it a versatile and useful material in many different industries. Here are some of the most common uses of wool fibre:

1. Clothing: Wool is a popular material for clothing due to its warmth, softness, and insulation properties. It is often used to make jackets, coats, sweaters, and other winter wear. Wool also has moisture-wicking properties, which help to regulate body temperature and keep the wearer comfortable.

2. Carpets and Rugs: Carpets and rugs are manufactured with wool due to its durability and resistance to wear and tear. It is also naturally resistant to dirt and stains, making it easy to clean and maintain.

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3. Upholstery: Wool is used as a stuffing material in upholstered furniture, such as sofas and chairs, due to its resilience and ability to hold its shape over time. It is also flame-resistant, making it a safe choice for home furnishings.

4. Bedding: Bedding, such as mattress toppers are made from wool, due to its insulation and moisture-wicking properties. It helps to regulate body temperature and keep the sleeper warm and dry.

5. Textile Manufacturing: Wool fibres are used in a variety of textiles, including woven and knitted fabrics, as well as felt. Wool fabrics are often used in the fashion industry for their softness and warmth, and in the outdoor industry for their insulation and durability.

6. Felting: Wool can be felted to create a dense, non-woven material that is often used for crafting, such as making hats and scarves. Felted wool is also used in the construction of insulation and soundproofing materials.

7. Agriculture: Wool is used in the agriculture industry as bedding for livestock, as it helps to regulate the temperature and provide insulation for the animals.

References:

  1. Principles of Spinning: Fibres and Blow Room Cotton Processing in Spinning by Ashok R. Khare
  2. An Introduction to Textile Coloration: Principles and Practice By Roger H. Wardman
  3. Protective Textiles from Natural Resources By Md. Ibrahim H. Mondal
  4. Textile Engineering – An Introduction Edited by Yasir Nawab
  5. Fibres to Fabrics by Bev Ashford

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  1. Classification of Textile Fibres
  2. Animal Fibres: Properties, Types and Uses
  3. Types, Properties and Uses of Silk Fibre

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