The Wonders of Wool

A few weeks ago I attended a seminar on extreme clothing in the Lakes where Mike Parsons (founder of Karrimor and now KIMM) and Mary Rose (co-author of Invisible on Everest, a history of outdoor gear I highly recommend) gave a talk on old-school “performance” fabrics. It sounds dull. It wasn’t.

They covered the usual Lancashire classics—Gabardine and Ventile—but also the first breathable waterproofs, used by the Aleutian Islanders thousands of years ago and made, incredibly, from seal intestines. They spoke about the Alpine Iceman and his grass jacket—waterproof, breathable, and maintained by keeping the roots attached. By the mid-20th century, natural fibres had become highly refined and deeply effective. Some may have been better than what we use today.

The most common performance material on early climbs and polar expeditions was wool. Unlike fur or feathers, wool proved robust, light, weather resistant—and crucially—warm when wet.

Wool’s finest hour may have come in 1953, when two men in Shetland jumpers stood on Everest. Hunt’s expedition had commissioned superfine Shetland yarn spun from the best neck fleece. The largest jumpers weighed just 185g. And yet, despite this refinement, wool was swept aside by synthetics promising lighter weight, greater toughness, and above all, lower cost.

Leaving the seminar, I wondered: if wool is still good enough for your feet, why isn’t it good enough for your body?

People had been asking me about wool base layers for years. I’d avoided them. I don’t wear traditional base layers much anyway, and I’d filed the wool revival under “people who also swear by silk underwear.”

AN ITCH IN TIME

My earlier experiences with wool were mixed. Years ago someone gave me a Swanndri bush shirt—much loved in New Zealand. I found it unbearable. It felt like wearing upholstery. I was told to “break it in.” That sounded suspiciously like the advice given when I bought second-hand Asolo Supersofts. They never broke in either. The cut was pure lumberjack. Fine for felling trees. Not for climbing.

Later I tried a thinner wool Zip-T from a company called Antarctica. Softer fibres. More technical cut. I’d been wearing Rhovyl, modal and polypropylene for wet warmth, so wool seemed backward. But I tried it.

In Scotland I was surprised. It felt comfortable. Luxurious even. It draped well. Too well, I thought—surely that meant poor technical performance. Function and fashion rarely share a tent.

In the hills it behaved differently from synthetics. Working hard, I felt dry heat rather than swampy dampness when wicking was overwhelmed. It felt natural. Part of me. On a wet Munro link-up, soaked through in drizzle, it stayed warmer than any synthetic I’d used, provided I stayed out of the wind. Even sodden, it maintained comfort. And it didn’t stink. It smelled of wool, yes—but naturally so, not like chemical warfare.

I wore it constantly. Climbing, travelling, working. It rarely needed washing. Eventually it died—not from use, but from a tumble dryer incident that reduced it to Action Man proportions.

WEAR THERE’S A WOOL

Curious, I tried a modern Merino piece from Icebreaker. Their Tech Top seemed the most technical offering. The sleeves extended over the hands with thumb loops—brilliant for warmth retention. The zip-neck and double-layer collar offered real venting control. The cut was long, simple, purposeful. Proper design, quietly done.

ALL HAIL THE SHEEP

Sheep have spent millions of years refining insulation. Down wins for pure warmth-to-weight in dry cold. But in wet mountains, wool excels. Synthetic fills are clever—but they rely on weave, treatments, chemistry. Wool fibres themselves breathe.

Each Merino fibre contains a hydrophilic core (keratin), cuticle scales, and a thin epicuticle. The core absorbs up to 30–35% of its weight in moisture vapour without feeling wet. The crimped structure traps resilient air. The fibre flexes tens of thousands of times without damage. It regulates. It buffers. It seeks equilibrium.

Synthetics are waterproof plastic. Wool is dynamic biology.

THE ECOLOGICAL FACTOR

Wool is renewable and biodegradable. It’s harvested from living animals. It avoids silver-impregnated anti-odour treatments common in synthetics. Processing isn’t impact-free—but compared to petrochemical fabrics, it’s arguably more responsible.

Wool also tends to be valued. People repair it. Keep it. Wear it for years. That matters.

DOES WOOL WORK?

In use, yes. It resists odour, performs well wet, clings less, and offers a broad comfort range. Paired with a light windproof, it covers most active conditions. It’s not that Powerdry or Capilene are poor—they aren’t. It’s that wool was undervalued.

The downside? Cost. About double many synthetics. But perhaps that reflects what it actually is.

WHY DID CLIMBERS STOP WEARING WOOL?

Wool dominated mountaineering for centuries. Loden capes. Shetland pullovers. Jaeger wool systems. Camel hair sleeping bags. Dachstein mitts. It worked.

Fleece changed things. Lighter when wet. Quick drying. Modern looking. At a time when wool was expensive and seen as old-fashioned, fleece offered a clean break.

Warmth-to-weight between fleece and wool is similar when dry. When wet, fleece dries faster. That convenience won.

Now wool prices have fallen and blends are improving. Sports wool is making a return. Perhaps the pendulum has simply swung back.

Mike Parsons (KIMMlite) and Mary Rose are co-authors of “Invisible on Everest: Innovation and the Gear Makers.”