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Questions and Answers
What is the effect of laundering on wool's strength when wet?
What is the effect of laundering on wool's strength when wet?
How does wool react to hot sulphuric acid?
How does wool react to hot sulphuric acid?
What type of bleach is considered safe for wool?
What type of bleach is considered safe for wool?
Which of the following properties of wool makes it vulnerable to mildew?
Which of the following properties of wool makes it vulnerable to mildew?
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What measures can be taken to protect wool from insects?
What measures can be taken to protect wool from insects?
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What are protein fibers primarily composed of?
What are protein fibers primarily composed of?
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Which of the following is NOT a characteristic of wool?
Which of the following is NOT a characteristic of wool?
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What is the primary source of silk?
What is the primary source of silk?
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What determines the quality of wool fiber?
What determines the quality of wool fiber?
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Which animal is NOT a common source of specialty wool?
Which animal is NOT a common source of specialty wool?
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What is the name of the protein present in hair fibers?
What is the name of the protein present in hair fibers?
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Which property allows wool to provide warmth even when wet?
Which property allows wool to provide warmth even when wet?
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What is the purpose of shearing sheep?
What is the purpose of shearing sheep?
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What type of wool is produced from Merino sheep?
What type of wool is produced from Merino sheep?
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What is the most significant use of purified lanolin?
What is the most significant use of purified lanolin?
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What classification is given to wool sheared from young lambs?
What classification is given to wool sheared from young lambs?
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Which class of wool is characterized by being coarser and used mainly for carpets and blankets?
Which class of wool is characterized by being coarser and used mainly for carpets and blankets?
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How does hogget wool compare to lamb's wool?
How does hogget wool compare to lamb's wool?
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What type of wool is sheared from sheep older than 14 months and may contain soil and dirt?
What type of wool is sheared from sheep older than 14 months and may contain soil and dirt?
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Which characteristic is NOT used for grading and sorting wool?
Which characteristic is NOT used for grading and sorting wool?
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Which layer of the wool fiber is responsible for its water repellence?
Which layer of the wool fiber is responsible for its water repellence?
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What percentage of impurities can raw or scoured wool contain?
What percentage of impurities can raw or scoured wool contain?
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What is the main feature of wool that contributes to its elasticity, loft, and cohesiveness?
What is the main feature of wool that contributes to its elasticity, loft, and cohesiveness?
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What type of wool is produced when sheep are slaughtered for meat, resulting in inferior quality?
What type of wool is produced when sheep are slaughtered for meat, resulting in inferior quality?
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Which layer of wool fiber is known to enhance its insulation properties?
Which layer of wool fiber is known to enhance its insulation properties?
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What is the primary protein that constitutes wool?
What is the primary protein that constitutes wool?
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What term describes the torn or discolored parts of the fleece?
What term describes the torn or discolored parts of the fleece?
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What type of chemical bond is the cysteine linkage in wool's structure?
What type of chemical bond is the cysteine linkage in wool's structure?
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In natural colored wools, what pigment is contained within the corticular cells?
In natural colored wools, what pigment is contained within the corticular cells?
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Cotty wool is characterized by its texture resulting from what specific conditions?
Cotty wool is characterized by its texture resulting from what specific conditions?
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Which of the following factors contributes to wool's excellent elasticity?
Which of the following factors contributes to wool's excellent elasticity?
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What is the maximum amount of stretching wool can undergo without tearing?
What is the maximum amount of stretching wool can undergo without tearing?
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Which property allows wool to retain heat effectively?
Which property allows wool to retain heat effectively?
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What is the diameter range of wool fibers?
What is the diameter range of wool fibers?
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What characteristic of wool allows it to quickly recover from wrinkling?
What characteristic of wool allows it to quickly recover from wrinkling?
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What happens to wool's strength when it gets wet?
What happens to wool's strength when it gets wet?
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Study Notes
Natural Protein Fibers: Wool & Silk
- Protein fibers are animal-based, including wool and specialty wools (animal hair), and silk (insect secretion) and spider silk.
- Animal sources for hair include sheep, vicuna, alpaca, camel, llamas, cashmere goats, angora goats, and angora rabbits. Silk comes from silkworms.
- Protein fibers are made of amino acids (carbon, hydrogen, oxygen, and nitrogen). Keratin is the protein in hair fibers; fibroin is the protein found in silk.
- Wool is a short, fluffy undercoat on wild sheep, initially used as a covering.
- Domestication of sheep likely stemmed from the need to use the fleece effectively, even matted, to create coverings.
- Modern sheep fleece is primarily soft downy undercoat, due to selective breeding.
- Wool is prized for warmth, moisture absorption, heat retention, resilience, water repellence, flame resistance, and felting ability.
- Australia, New Zealand, England, Russia, Argentina, Uruguay, South Africa, and the US are major sheep-breeding countries.
Processing of Wool
- Wool quality depends on the sheep's breeding, climate, food, care, and health.
- Shearing sheep annually removes the fleece using power shears (or chemical methods) for continuous pieces.
Classification of Wool
- Wool classification can be done by the type of sheep or by the fleece type.
- Sheep classifications:
- Class I (Merino): Short (1-5 inches), strong, elastic fibers with high crimp and scale count, ideal for high-quality clothing.
- Class II: Longer (2-8 inches), strong, fine, elastic, with a good crimp and scale count, suitable for good-quality clothing.
- Class III: Intermediate (4-18 inches), coarse, few scales, smoother, suitable for clothing.
- Class IV (Mongrels): Coarse, hair-like, fewer scales and crimp, used in carpets, rugs, blankets, and lower quality clothing.
- Fleece classifications: based on age (e.g., lamb's wool, hogget wool, wether wool), whether pulled (after slaughter), or from dead animals (dead wool), and whether matted/damaged (e.g., cotty wool, taglocks).
Types of Wool
- Lamb's wool: First shearing from 6-8 month-old lambs, fine quality, tapered ends, soft fabric.
- Hogget wool: First shearing of 12-14 month-old sheep, fine, soft, resilient, tapered ends.
- Wether wool: Sheared from sheep over 14 months, variable quality, may contain dirt/soil.
- Pulled wool: Pulled during slaughter, inferior quality.
- Dead wool: From accidentally killed sheep, lowest grade.
- Cotty wool: Damaged/matted wool, inferior quality.
- Taglocks: Torn/ragged fleece parts, inferior quality.
Physical Structure of Wool
- Wool fibers have a complex structure: cuticle (outermost layer with scales, contributing to water repellence and felting), cortex (main part made of cells with melanin for color), and medulla (in coarse wool only, honeycomb like with air spaces for insulation).
Properties of Wool
- Length & Diameter: Varies from 1.5 to 16 inches and 10-50 microns in diameter.
- Microscopic View: Uneven structure that tapers to the tip, with overlapping scales.
- Strength: Weakest of natural fibers, loses strength when wet.
- Elasticity: Good elasticity, stretches up to 25-30% of its length. Resilient (quickly returns to shape).
- Drapability: Excellent drapability due to flexibility, elasticity, and resilience.
- Heat Conductivity: Poor conductor, keeping the body warm.
- Absorbency: Initially water repellent but absorbs water, drying slowly.
Chemical Composition
-
Primarily keratin, made of carbon, hydrogen, oxygen, nitrogen, and sulfur; with 18 different aminos acids.
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Wool has natural cross-links (cystine/sulfur linkages).
Biological Properties
- Mildew resistance: Wool can be affected in high moisture conditions.
- Insect resistance: Generally resistant to moths and carpet beetles, but should be stored with protection (i.e. neem leaves).
Uses of Wool
- Apparel, blankets, rugs, carpets. Can be blended with other fibers.
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Description
Explore the fascinating world of natural protein fibers such as wool and silk. Learn about their sources, properties, and the importance of these fibers in textiles. Discover the role of amino acids in their structure and the significance of domestication in wool production.
