Fabric & Care
Cotton, wool, linen, silk: what each fibre actually does
Every fibre is a set of trade-offs between warmth, moisture handling, strength and how it behaves when wet. Knowing them makes composition labels informative rather than decorative.
A fibre's properties come from its physical structure, and the structure explains the behaviour. Once you know why linen creases, you stop being annoyed by it.
Cotton
A cellulose seed fibre, essentially a flattened hollow tube that twists along its length. That twist is what makes it spinnable and gives cotton yarn its characteristic softness.
Strengths: comfortable against skin, absorbent — up to around 25 per cent of its weight in moisture — and notably stronger when wet, which is why it tolerates washing so well. Takes dye readily. Cheap.
Weaknesses: absorbs moisture and holds it, so it dries slowly and stays cold and clammy once wet. Wrinkles readily. Poor insulation when damp — the reason "cotton kills" is a hiking maxim.
Staple length matters more than the name. Egyptian, Pima and Supima refer to extra-long staple cottons, which produce smoother, stronger, less pilling yarn. "Egyptian cotton" is not a protected term in most markets and is applied loosely, so it is a weak signal on its own.
Wool
A protein fibre with a scaled outer surface and a crimped, springy structure.
Strengths: the crimp traps air, making it warm for its weight. It absorbs up to about 30 per cent of its weight in moisture without feeling wet, because the moisture is held inside the fibre while the surface stays hydrophobic — which is why wool insulates when damp. It is naturally odour-resistant, flame-resistant, elastic — a wool fibre can be stretched and recover repeatedly — and creases fall out when hung.
Weaknesses: weaker when wet. Vulnerable to moths, which eat the keratin. Felts and shrinks irreversibly with heat and agitation, because the scales interlock. Damaged by the protease enzymes in biological detergents.
Micron count measures fibre diameter and determines softness. Below about 18.5 microns is superfine merino, soft against skin. Above about 25 microns starts to feel scratchy. The prickle sensation is mechanical — coarse fibre ends pressing on skin — rather than an allergy, which is why people who "can't wear wool" are frequently fine in fine merino.
Wool's elasticity means a suit recovers its shape overnight, sheds creases from a day of sitting, and drapes rather than clinging. No synthetic reproduces the combination of breathability, moisture handling and recovery, which is why the fibre survived the arrival of materials that beat it on every individual measure.
Linen
A bast fibre from the flax stem — long, straight, with almost no elasticity.
Strengths: the strongest natural fibre in common use, and stronger wet than dry. Highly absorbent and, unlike cotton, dries quickly. Conducts heat away from the body efficiently, which is what makes it feel cool. Becomes softer with every wash and lasts for decades.
Weaknesses: creases immediately and permanently within a wear, because the fibre has no elasticity to recover with. Frays. Expensive, because processing flax is labour-intensive.
The creasing is not a defect to be solved; it is the fibre. Linen blended with enough synthetic to stop creasing has lost most of what made it worth buying.
Silk
A protein filament extruded by the silkworm, and the only natural fibre that comes as a continuous filament rather than a staple.
Strengths: extraordinary strength for its weight. Smooth, so it feels cool and slips against skin. Takes dye brilliantly, producing colour saturation no other fibre matches. Insulating despite its lightness. Drapes better than almost anything.
Weaknesses: weakened by sunlight, by perspiration, by alkaline detergent and by chlorine. Water-marks readily. Weak when wet. Expensive.
Momme is silk's weight unit. 12–16 momme is typical for shirting and scarves; 19–25 for bedding and heavier garments.
The others worth knowing
Cashmere — the fine undercoat of the cashmere goat, around 14–19 microns, extremely soft, warm and short-stapled, hence the pilling. Quality varies enormously and price is a reasonable guide.
Alpaca — warmer than sheep's wool, less elastic, no lanolin, drapes heavily.
Mohair — from the angora goat, with a distinctive lustre and considerable strength, often blended.
Hemp — similar to linen, coarser initially, softens substantially, very durable.
Ramie — strong, lustrous, brittle, usually blended.
Reading a composition label
Percentages are listed by weight, highest first. Some practical translations:
Cotton with 2–5% elastane — added stretch and recovery, at the cost of longevity, since elastane degrades over time and with heat.
Wool blended with polyester or acrylic — cheaper, more crease-resistant, and prone to permanent pilling. In suiting, above about 30 per cent synthetic the cloth loses wool's drape and breathability.
Viscose, rayon, modal, lyocell — regenerated cellulose. Made from wood pulp, so plant-derived but chemically processed. Soft, drapey, absorbent, and weak when wet, which is why viscose garments frequently distort in the wash. Lyocell is produced in a closed-loop solvent process and is the most environmentally defensible of the group.
Polyester — strong, cheap, hydrophobic so it wicks rather than absorbs, holds pleats, and holds odour tenaciously. Pills permanently. Excellent in technical clothing, poor next to skin for long wear.
The practical summary
For warmth in changeable weather, wool. For heat, linen or an open-weave cotton. For next to skin in ordinary conditions, cotton or fine merino. For anything you want to keep a decade, natural fibres in a heavier weight.
And for anything with a stated performance function — waterproofing, wicking, compression — synthetics are usually the right answer, and worth accepting the trade-offs for.
