Textile Fiber Characteristics: Wool, Silk, Cotton, and Linen

Posted on Sep 29, 2025 in Biology

Fundamental Fiber Terminology

  • Fiber Definition

    A fiber is a single filament, often characterized by a very small diameter relative to its length. Fibers contribute significantly to the hand feel and texture of fabrics.

  • Filaments

    Filaments are continuous, long strands of indefinite length. They can be smooth or textured.

  • Continuous Filament Cable

    This refers to a rope or a bundle composed of thousands of artificial fibers twisted together in a defined torsion.

Protein Fibers (Natural Animal Fibers)

Protein fibers are derived from animal sources, such as animal hair (e.g., wool) or insect secretions (e.g., silk). They are composed of various amino acids found in nature.

Wool

Wool Properties

  • Conformability: Capacity to conform to the body due to heat and humidity.
  • Moisture Absorption: High capacity to absorb moisture and steam.
  • Flame Retardant: Water repellency and inherent flame resistance.

Kemp Fiber

Kemp is a coarse, white, opaque, and brittle fiber found in sheepskins.

Production and Classification

  • Production: Fine and soft wool is typically obtained from the first clipping of young animals (not removed before 7 months).
  • Classification and Selection: Wool is grouped based on similar characteristics, judging the fineness and length of the fleece.

Key Fiber Characteristics

Preferred characteristics based on breed include:

  • Fineness
  • Undulation (Crimp)
  • Strength
  • Length
  • Elasticity

Wool Types and Sources

  • Color: Wool often appears yellow, caused by exposure to sunlight and heat.
  • Virgin Wool: Wool that has never been processed in any way.
  • Legislation/Sources: Wool corresponds to the fleece of the sheep and can come from different sources:
    • Sheared Wool (from live sheep).
    • Limed Wool (from the skins of sheep used for meat).
    • Reused Live Sheep Wool.
    • Reprocessed Wool (from scraps and waste of new fabrics).

Structure and Durability

  • Chemical Composition: The protein component is called keratin.
  • Aesthetic Properties: Contributes volume and body to fabrics.
  • Durability: Individual wool fibers are weak, but the resulting fabrics are very durable due to excellent elongation and flexibility. It is naturally water repellent.

Care and Felting

  • Felting (Enrieltado): A unique property based on the fiber’s scale structure. Fulling (Batanes) is a finishing process where fabrics are washed in a concentrated soap solution and squeezed between wooden rollers to shrink the fabric and close the weave by thread proximity.
  • Conformation: Fabrics can be heat-formed using moisture. Excess fabric is cut using clamps/irons.

Chemical Reactions and Vulnerabilities

  • Acids: Wool resists mineral acids but is sensitive to alkalis (it turns yellowish, sticky, and dissolves).
  • Organic Solvents: Highly resistant to solvents used for dry cleaning.
  • Pests: Attacked by moths and other insects.
  • Temperature: High temperatures weaken and harden the fiber; it burns easily.
  • Fire: Burns very slowly and self-extinguishes.

Wool Care Instructions (Avoid)

  • Bleach
  • Agitation
  • Alkalis
  • Hot water

Specialty Animal Hairs

Wool alternatives and specialty fibers:

  • Mohair: (Angora goat, yields about 2 kg per year). Features a circular cross-section and silk-like luster.
  • Qiviut: (Undercoat of the domesticated musk ox).
  • Cashmere: (From China, Mongolia, Tibet). Varies in color from white to gray.
  • Camel Hair: Known for better insulating properties than other wools.
  • Llama and Alpaca: Distinguished by their gloss, smoothness, and fineness.

Silk

Silk Properties

  • Dry hand feel.
  • Natural luster.
  • High moisture absorption.
  • Excellent drape.
  • High resistance/strength.

Silk Production

Production begins with the silk moth depositing eggs on prepared papers. When the worms hatch, they feed on leaves. After several days, they fill with liquid silk and begin spinning their cocoons.

  • The two filaments are surrounded by a silk gum called Sericin.
  • To obtain the continuous filament, the larvae must be sacrificed before they emerge as moths.
  • The cocoon is boiled to kill the larvae and soften the sericin.
  • Reeling occurs after boiling to unwind the thread into a skein.

Physical Characteristics and Care

  • Structure: Continuous filament; smooth, irregular, solid, and fine diameter.
  • Durability: A strong fiber.
  • Care: Does not shrink or soil easily (dry cleaning is preferred). Resistant to diluted acids and organic solvents. Sensitive to sunlight (turns yellow). Degraded by sweat. Produces a crackling sound when wrinkled.

Cellulosic Fibers (Plant-Based)

Cotton

Cotton Properties

  • Durability: Medium resistance.
  • Cost and Convenience: Low cost and easy washing.
  • Comfort: Produces very pleasant fabrics due to high absorbency and being a good conductor of heat and electricity.
  • Vulnerabilities: Damaged by acids; oxidized by sunlight; not thermoplastic.

Cotton Production

Cotton is a crop. After the flower appears, the bud grows, containing the seed where the fibers develop. When mature, the boll opens, projecting outward as fluffy fibers resembling a tassel.

Linen (Flax)

Linen is a bast fiber derived from the stem of the flax plant.

Linen Characteristics

  • Aesthetics: Low resilience, thick and thin yarn variation, soft luster, low elasticity.
  • Cross-Section: Polygonal with rounded ends.
  • Durability: Strong fiber, highly resistant to rupture.
  • Comfort: Good moisture recovery, no static buildup, good heat conductor.
  • Care: Resistant to alkalis and organic solvents, even at elevated temperatures.

Ramie

Ramie is grown in warm and humid climates and is very similar to flax.

  • Color: Pure white.
  • Strength: Strong fiber; strength increases when wet.
  • Luster: Silk-like luster.
  • Resistance: Good resistance to mold and other organisms (waterproof).
  • Drawbacks: Rigid and brittle; lacks resilience and has low elasticity.

Hemp

  • Historically not widely used for apparel.
  • High strength.

Jute

  • Cheap fiber.
  • Short and brittle fibers.
  • Low resistance to sunlight; poor color retention.
  • Brittle; cracks and tears easily.