Introduction to Wool Fiber | Merino | Wool fiber

Merino wool

Introduction to Wool Fiber | Merino | Wool fiber 

Mr. Prathamesh Warade
Government Polytechnic, Nagpur


Wool is the textile fiber, which is a reusable and recyclable fiber on the planet. Wool is mainly obtained from sheep for Ex Australian merino wool. The wool comes under the category of animal fibers. Wool fiber is soft, durable, safe in nature, and has high wear and tear resistance. Wool has enjoyed widespread as an apparels fiber and interior textiles. Wool is a fibrous protein and keratin. Wool can be regarded as an active fiber. Wool has a saturation regain of 35%. Wool fiber has a morphological structure and it consists of three parts they are : cuticle, cortex, and medulla. The wool fiber comprises Carbon, hydrogen, oxygen, nitrogen, sulfur. The wool fibers are composed of protein macromolecules. 

Technical terms to be kept in mind :

  • High ignition temp. (750-800°c) 
  • Low heat of combustion ( 196kj/g) 
  • A high nitrogen content ( 16%) 
  • A high moisture content ( 10-14%) 

A major amount of wool is produced in Australia and New Zealand. The grading is classified as fine, medium, long, crossbred, and mixed. The quality of wool for textile purposes depends on:

1) breed of sheep, 2) the location on the body 3) The extent of contaminants.

Mostly wool fibers can be manufactured into two kinds of yarn or cloth they are worsted or woolen. Wool fiber is warm to the touch, feels elastic. During the period of 1950-1990, the Australian wool corporation chaperoned the wool producers towards more efficient fleece preparation. The merino breed is highly concentrated by Australian wool production.  Nominated directors with additional director representing CSIRO and they are as follows:

  • Australian Council of Wool Exporters.
  • Federal Council of Private Treaty Merchants.
  • National Council of Wool Selling Brokers of Australia.
  • Wool Council of Australia.
  • Wool Scourers and Carbonisers Association of Australia.
  • Wool Textile Manufacturers of Australia. 

Wool has a heterogeneous composition where the protein is made up of amino acids and acidic carboxyl groups. Wool is considered the ideal fiber for cold weather conditions.

Physical properties of the wool fiber are:

  • Length: the length of wool fiber varies greatly from 3.6cm to 35 cm. The various wool fibers can be divided into three varieties .i.e. fine, medium, and coarser. Fine wool varies from 3.2 cm to 10 cm, medium wool from 5cm to 20 cm, and coarser wool from 15 cm and more. 
  • Fineness: Finer fiber is suitable for fine wool yarn. The fineness ranges from 10 - 70 microns.
  • Cross-section: Greatly varies from circular to elliptical.
  • Crimp: The crimp of wool fibers contributes to spinning quality. It varies from 0 - 30 microns each.
  • Strength: The strength of the wool fiber is poor compared to other textile fibers due to low orientation in fine structure. The tensile strength varies accordingly and ranges from 1600 - 2150 kg/cm³. 
  • Elasticity: Wool fiber can be elongated up to 30% without any deformation or weakening.
  • Hysteroscopic property: Wool is more hysteroscopic than any natural fiber. Wool can absorb as much as 25% moisture.
  • Specific gravity : 1.30gm/cc
  • Electrical properties: Wool is a bad conductor of electricity. 

( Note: Wool fibers are epithelial growth of mammals which is usually known as hair fibers )

Chemical properties : 

  • The action of heat: wool is fire resistant. Wool when burnt gives a characteristic odor when removed from the flame, wool will stop burning and every single fiber exhibits a black knob on its end. 
  • Effects of water and steam: when wool is exposed to water and steam, with or without tension wool will change in its shape and affinity to dye. 
  • Plastic properties: plastic wrapping are regularly treated to make them hydrophilic so that they retain the printing inks used for labeling. Wool loses its rigidity almost completely in boiling water. 
  • Isoelectric and isoionic points: the isoionic point is around 4.8-5.0. Wool does not combine with any alkali below ph 10. 
  • Dyeing property: wool can be easily dyed with acid dyes, basic dyes, and direct color in neutral. In alkaline conditions, wool fiber cannot be dyed.


  • Wool's resilience, bulk, and ease in handling make it the most appropriate in knitting goods.
  • Wool's long-standing reputation for warmth can be attributed to its high natural bulk and elasticity.
  • Moisture absorption by wool
  • As humidity rises increases the fiber temperature, and moisture release following a decrease in humidity lowers it.
  • Wool has such a large capacity to absorb water vapor compared with other apparel fiber.
  • As described earlier about woolen and worsted fibers they can be used in men's and women's suiting, overcoat, sweaters, upholstery fabric, and blankets.
  • Wool quickly absorbs odor " sweating " and desorbs odor " washing ".
  • Wool's fabric surface is hydrophobic and cannot be penetrated by bacteria.
  • Wool absorbs and evaporates moisture keeping you dry and cool.
  • Wool fiber can be used for waddings (fillings), which provides superior breathability and insulation.
  • Merino wool has long been the preferred material for firefighters’ uniforms.

References :

  • Wool : science and technology , Woodhead publication limited , Cambridge England
  • A text book of fibre science and technology by S.P. mishra , new age international publishers
  • The wool fibre and it's application , dr. Geoff Naylor , CSIRO textile and fibre technology

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