Textile Fiber Families: Classification, Sources, and Trade Relevance

Why Fiber Identification Matters in Garment Care

Every cleaning decision—water temperature, solvent choice, agitation level, drying heat—depends on knowing what the fabric is made of. A fiber that survives vigorous hot-water washing may be destroyed by the same treatment applied to a neighboring fiber. Before you touch a garment, you must be able to classify its fiber content, understand its key properties, and predict how it will respond to cleaning chemistry and mechanical action. This lesson gives you that foundation.

The Three Fiber Families

Natural fibers come from plants or animals and existed long before manufactured textiles. The two main subgroups are cellulosic (plant-based) and protein (animal-based).

• Cotton is a seed-hair fiber composed almost entirely of cellulose. It is strong, especially when wet, absorbs moisture readily, and tolerates moderately high wash temperatures. It is damaged by strong acids but resists alkalis, which is why alkaline detergents work well on cotton. Cotton's high moisture regain (roughly 7–8% under standard conditions) means it swells when wet, which can cause shrinkage if heat is applied carelessly during drying.
• Linen (flax) is also cellulosic. It is stronger than cotton and has lower moisture regain, but it wrinkles easily and is sensitive to abrasion at fold lines.
• Wool is a protein fiber from sheep fleece. Its surface is covered with overlapping scales. When those scales interlock under heat, moisture, and agitation, felting and irreversible shrinkage occur. Wool is damaged by strong alkalis (which break peptide bonds) and by chlorine bleach. It requires controlled, low-agitation wetcleaning or drycleaning.
• Silk is a continuous protein filament reeled from silkworm cocoons. It is lustrous and lightweight but weakens noticeably when wet. Silk is sensitive to alkalis, perspiration (which can cause color loss), and prolonged exposure to sunlight. It is also damaged by chlorine bleach and high heat.

Regenerated (man-made cellulosic) fibers are produced by chemically processing natural cellulose—usually wood pulp—into a fiber form. The cellulose origin gives them some properties similar to cotton, but the manufacturing process changes others.

• Rayon (viscose) is significantly weaker when wet than when dry—sometimes losing more than half its dry strength. It shrinks readily in water and must be handled gently. Many rayon garments carry a "dry clean only" label for this reason.
• Lyocell (Tencel) is a newer regenerated cellulosic made in a closed-loop solvent process. It is stronger than rayon, both wet and dry, but still prone to fibrillation (surface fuzz) under agitation.
• Modal is a high-wet-modulus rayon variant with improved wet strength and less shrinkage than standard rayon.
• Acetate and triacetate are regenerated fibers derived from cellulose acetate. They have low moisture regain and are solvent-sensitive—acetone and some common spotting agents will dissolve acetate. Triacetate is more heat-stable than acetate.

Synthetic fibers are made entirely from petrochemical polymers. They generally have low moisture regain, excellent wet strength, good resistance to most cleaning solvents, and thermoplastic behavior (they soften and deform under excess heat).

• Polyester is the most widely used synthetic in apparel and commercial laundry. It has very low moisture regain, good abrasion resistance, and retains creases set by heat. It is thermoplastic: too much heat in the dryer or with a pressing iron will cause permanent distortion. Polyester also tends to retain oily soil because of its hydrophobic character.
• Nylon (polyamide) is strong, abrasion-resistant, and elastic. It has low moisture regain but absorbs enough moisture to allow some dye transfer when wet. Nylon yellows with prolonged exposure to sunlight and is weakened by strong oxidizing bleaches.
• Acrylic is a soft, wool-like synthetic. It is thermoplastic and prone to pilling. High heat during drying causes permanent elongation or distortion.
• Spandex (elastane) is always blended with other fibers to provide stretch. It is degraded by chlorine bleach and high drying temperatures.

Key Properties That Drive Cleaning Decisions

| Property | What it means | Cleaning consequence |

|---|---|---|

| Moisture regain | % moisture a fiber holds at standard conditions | High regain = swelling risk; low regain = poor wetting |

| Wet strength | Tensile strength when saturated | Low wet strength (rayon) = gentle handling required |

| Heat sensitivity | Softening/melting behavior | Synthetics distort; protein fibers scorch |

| Solvent resistance | Response to drycleaning solvents | Acetate dissolves in acetone; most synthetics are solvent-stable |

| Alkali/acid sensitivity | Response to pH extremes | Wool/silk damaged by alkali; cotton damaged by strong acid |

Safety Notes

When handling raw fiber samples and chemical spotting agents during lab work, wear nitrile gloves and safety glasses. Some spotting agents used on acetate or for oily-stain pre-treatment contain volatile solvents; work in a ventilated area and follow the Safety Data Sheet (SDS) for each product. Never mix spotting agents without knowing their compatibility. Store solvent-based materials away from heat sources.