Wool versus wool blend, and what each percentage does

A composition label is the most useful two lines on a coat and the part most people skip. It is also easy to misread, because the headline percentage tells you less than the order of the fibres and nothing at all about the weight of the cloth. Here is what each of the common blends actually does once the coat is on a cold platform, and where a label stops being able to help you.

What the label is obliged to tell you

Fibre content is listed by weight, in descending order. So 60% polyester, 40% wool is a polyester coat with wool in it, whatever the photography suggests, and the words in the product title are marketing rather than information.

Watch for the exact wording too. Wool on its own means sheep's wool. Virgin wool means wool that has not been used before. Recycled wool, sometimes sold as shoddy, is reclaimed fibre that has been shredded and respun, which shortens the fibres and makes the cloth pill sooner. Lambswool is from the first shearing and is softer. Merino refers to the breed and usually means a finer fibre.

What the label is not obliged to tell you is the weave, the finish or the weight of the cloth, and those decide whether the coat is warm. More on that below, because it is the single biggest gap between a label and a wearing experience.

What wool itself does

Wool fibre is crimped rather than straight, so a wool cloth holds a lot of still air for its thickness, and still air is what insulation is. It also absorbs a large amount of moisture vapour before it feels wet at all, which is why a wool coat in drizzle feels dry when a synthetic one feels clammy.

Two less obvious properties matter for a coat. Wool recovers from creasing on its own if you hang it, which is why a wool coat that spent four hours folded on a train seat looks fine the next morning. And wool does not melt: it chars and tends to self-extinguish, where polyester and acrylic melt and stick.

Its weaknesses are real as well. Wool felts and shrinks if you wash it warm and agitate it, it is the fibre clothes moths actually want to eat, and it is heavier per unit of warmth than a synthetic fill. A full-length wool overcoat is a surprisingly heavy object.

Reading the blends, percentage by percentage

Above roughly 80% wool, the cloth behaves like wool. You get the warmth, the recovery, the handle and the weight, and the small synthetic percentage is usually there for strength or to stabilise the weave.

Between about 50% and 70% wool, you get a usable compromise: most of the warmth, better crease resistance, a lower price, and a surface that holds a pressed line. Below about 30%, stop thinking of it as a wool coat. The dominant fibre is driving the behaviour, and the wool is contributing handle rather than performance.

A 50/50 blend is not halfway between the two experiences, which is the thing that surprises people. Synthetics tend to dominate the surface behaviour, so a half-and-half cloth often feels more synthetic than the number suggests: slightly shinier, more prone to static, and less good at shedding damp.

The second fibre is the one to read

Polyester adds strength, crease resistance and cost control, and reduces breathability. It is the most common partner and the least interesting one. Polyamide, which you may see called nylon, adds abrasion resistance for very little weight, which is genuinely useful at cuffs and elbows, and 5% to 15% of it in an otherwise woolly cloth is a good sign rather than a bad one.

Acrylic is the one to be wary of. It is there to imitate the handle of wool cheaply, and it does that well on the rail and badly after twenty wears: it pills heavily, it goes shiny at pressure points, and it holds odour. Viscose adds drape and a slight sheen, wrinkles readily and loses strength when wet. Elastane at 1% to 3% adds a little give, but it degrades faster than everything around it and it makes alterations and hard pressing harder.

Cashmere, alpaca and mohair percentages are about hand rather than durability. A small cashmere percentage genuinely changes how a coat feels against the neck. It also pills more than sheep's wool, so a high-cashmere coat is a luxury with a maintenance bill, not an upgrade in toughness.

The number that matters more than the fibre

Weight, given in grams per square metre, tells you more about warmth than composition does. Coating cloths generally run from around 300 gsm for something like a light overcoat up to 500 gsm and beyond for a heavy melton. A 100% wool coat at 280 gsm will be colder than a 60% wool coat at 480 gsm, every time.

The finish matters too. Melton is milled and cropped so the surface closes up and blocks wind. Boiled wool is deliberately felted. A loose twill in the same fibre will be noticeably draughtier. If a product page gives you a weight or a cloth name, that is worth more than the percentage.

If a listing gives you neither, ask. We would rather go and read a supplier's spec sheet for a coat like The Oversized Long Coat than let you buy on an assumption, and if we cannot get a straight answer we would rather tell you that too.

Where composition stops being the question

A lined coat has two compositions, and the lining matters for how the coat goes on over a jumper. A slippery lining lets a sleeve pass over knitwear. A cotton or jersey lining grips it, and you will fight the coat every morning.

Some coats have no fibre blend to read in this way at all. A faux leather coat like The Belted Trench is a plastic coating over a backing cloth, so the questions are about the coating and the storage rather than about percentages. A smart tailored shape such as The Suit Trench is driven as much by the interlining and the pressing as by the cloth.

The short version: read the order of the fibres, treat anything under 30% wool as not a wool coat, look for polyamide and be suspicious of acrylic, and chase the cloth weight if you can get it. Then put the coat on and judge the shoulder, because no label has ever fixed a bad shoulder.

Questions people actually ask

Is a wool blend coat warm enough for winter?

It can be, and the fibre percentage is not what decides it. Cloth weight does. A heavy blend at 450 to 500 grams per square metre will beat a thin pure wool coat at 280. Read the weight if the listing gives one, and treat anything under about 30% wool as a synthetic coat.

What does 70% wool 30% polyester mean in practice?

It means a coat that keeps most of wool's warmth and crease recovery, resists wrinkling a little better, costs less and breathes slightly less well than pure wool. It is the most common compromise in coating cloth and a reasonable one.

Is acrylic bad in a coat?

It is the weakest of the common blend fibres for outerwear. Acrylic imitates wool's handle cheaply but pills heavily, goes shiny at pressure points and holds odour. A high acrylic percentage is the clearest sign that a coat is built to a price.