The best summer suit you will ever wear is made of wool, which most people find hard to believe. The right cloth for a thing is very often not the obvious one, and the gap between obvious and right is where most disappointing purchases live.
| garment | the cloth | why |
|---|---|---|
| Summer trousers, relaxed | Linen, or linen with viscose | linen moves heat and moisture away quickly; the viscose softens the creasing |
| Summer trousers, tailored | High-twist wool, fresco or tropical | breathes about as well as linen and creases far less |
| Raincoat | Coated polyester or nylon, or waxed cotton | the water resistance is in the finish and the weave; nylon for lightness, polyester for sunlight |
| Winter coat | Dense wool melton, or wool with cashmere | wool keeps much of its warmth when damp, and handles a drizzly walk better than most |
| Tailored jacket | Wool twill or hopsack | wool can be moulded with steam and an iron, which synthetics barely respond to |
| Slip dress, bias cut | Silk charmeuse, or viscose satin | the bias needs weight to fall; polyester satin is usually too stiff to spiral |
| Jeans | Rigid cotton twill, or 1–2% elastane with a recovery yarn | rigid holds its shape; a stretch jean recovers only as well as its yarn is built, and the label does not say how |
| T-shirt | Combed cotton jersey, a little elastane at the neck | the elastane is there to stop the neckline going slack, not to fit you |
| Knitwear, next to skin | Fine merino | the micron count decides whether it itches, and the price does not |
| Summer dress | Cotton lawn or voile, linen, or Tencel | all three carry moisture; Tencel adds drape without viscose’s weakness in water |
| Lining | Viscose or cupro | a polyester lining traps much of the moisture the wool would otherwise carry away |
A tailored jacket is wool because wool can be set with steam. Shoulders shaped, lapels rolled, a chest built in. Synthetics barely respond to an iron in the same way, so a polyester blazer tends to sit flatter across the shoulder however good the pattern underneath it was. If you own one that never quite looks right in photographs, look at the shoulder first. It is very often the shoulder.
An uncoated polyester is not waterproof. The water resistance of a raincoat lives in the coating, the membrane, or the tightness of the weave. The fibre only decides weight, how it handles abrasion, and how it copes with sunlight. “100% polyester” on a rain jacket tells you approximately nothing about whether you will arrive dry.
Bias needs weight. A slip dress cut on the bias spirals and clings because the cloth is heavy enough to pull itself downward at 45° to the grain. Silk charmeuse does this beautifully. Polyester satin, which can look identical on a screen and costs a fraction as much, is usually stiffer and lighter, so it tends to hang in flat panels and read as a costume. It is one of the widest gaps between how a dress photographs and how it behaves.
A wool coat lined in polyester breathes less well than one lined in viscose or cupro, so the wool cannot do much of what it was chosen for, and you may well end up damp inside an expensive coat.
It is the cheapest possible saving in outerwear and the easiest to check: turn the coat inside out at the hem, find the composition label on the lining, and look for viscose or cupro. Thirty seconds, in the shop, before you have spent anything.