Why Wool Keeps You Warm When Wet
Why Wool Keeps You Warm (to a Certain Extent) Even When Wet
Why Wool Keeps You Warm (to a Certain Extent) Even When Wet
Many rumors and myths surround what happens when wool gets wet. Does it lose its insulating properties, or does it retain them? Does it even actively generate some warmth? To help you prepare for your next adventure, we’ll shed some light on the matter.
HOW WOOL ISOLATES
To understand this, first grasp what gives wool its insulating properties: wool fibers never have a smooth surface. For this reason, two wool fibers never lie perfectly on top of each other and therefore don’t form a seamless transition.
Instead, when wool is spun, countless tiny air pockets form and trap air. Because still air is a very poor conductor of heat, your body heat is only released to the outside to a very limited extent. The insulating effect of these air pockets makes wool an excellent choice in cold temperatures, as it keeps your body heat close to your body rather than releasing it into the cold ambient air. As a result, wool keeps you comfortably warm in winter.
The finer the wool fibers in the material your garment is made from, the stronger the insulating effect. This is because exponentially more ultra-tiny air pockets form between finer wool fibers, trapping warm air and thus serving as an insulating layer against the cold outside air.
Warms even when wet
For the same reason, our yak and camel wool are significantly warmer than merino wool. Yak and camel fibers are finer than conventional merino wool, allowing more air pockets to form between them, which act as an insulating layer.
To maintain the insulating effect, these air pockets must stay intact. Without them, no air is trapped to insulate and retain your body heat.
THE MAGICAL 30–35%
This is where something you’ve surely heard many times before comes into play (we’ve done our fair share of spreading the word): Wool can absorb up to 30% of its own weight in moisture without feeling wet (On a side note: Our yak wool actually absorbs up to 35% of its own weight in moisture). This is often immediately followed by the statement: “That’s why it keeps you warm even when wet.”
But wait: What does one thing have to do with the other? The explanation is actually quite simple: Up to the magic threshold of 30–35% of its own weight, a wool fabric absorbs moisture without altering its basic structure. The moisture is absorbed by the fibers themselves, rather than accumulating between them. This means the air pockets remain intact, and with them, the warming insulating layer.
Unlike many materials, whose insulating effect drops as soon as the first drop of moisture hits them, wool’s thermal performance stays intact for quite some time, even in light rain and sweat, providing you with superior warmth in most weather conditions.
Beyond 30–35%, wool also begins to lose its insulating power. Water molecules displace air pockets between the fibers. Because water, unlike air, conducts heat more efficiently, the wool now releases body heat to the outside, and its thermal performance decreases.
However, wool loses its insulating ability more slowly than other materials and retains its basic structure even when wet, so it performs better than wet cotton and synthetic fibers and protects you from the cold longer. In addition, wool is water-repellent: in light rain, unlike cotton or synthetic fibers, it often stays dry for several hours and thus retains its insulating effect. Another advantage of our yak and camel wool: yak and camel hairs are hollow on the inside and filled with air. When the wool gets wet, the water displaces the air pockets between the individual wool fibers. However, the hollow space within the yak and camel fibers remains filled with air—at least until you’re swimming in your functional clothing. As a result, even when completely wet, yak and camel wool retains significantly higher insulating properties than other materials and wool types.
Because we also use a heavier knit than most functional clothing made of merino wool, it takes correspondingly longer for our wool to exceed the 30–35% moisture threshold, as the moisture initially distributes evenly throughout the entire fabric. As a result, your functional clothing made of yak and camel wool keeps you warm and dry up to twice as long as merino wool.
There’s no such thing as bad weather. There’s only bad clothing.
HOW WOOL ACTIVELY GENERATES HEAT
But there’s a second property that makes wool one of the best fabrics for wet weather: When wool gets wet, it actively releases heat.
This property comes from a chemical reaction inside the wool fiber. When wool comes into contact with water vapor, a water molecule binds to the inner core of the wool fiber in an exothermic process called adsorption. The resulting hydrogen bonds release thermal energy, which leaves the wool in the form of heat.
So the myth is true: Thanks to this chemical reaction, wool not only insulates your body heat but even actively generates heat.
The more wool that can react, the greater the warming effect. Here, too, our performance clothing made of yak and camel wool has an advantage: Because of the heavier knit we use, it contains significantly more wool. As a result, it not only keeps you dry longer but also releases up to twice as much heat when wet as comparable functional clothing made of merino wool.
WHERE EVEN WOOL REACHES ITS LIMITS
To ensure you’re prepared for your next mission, we also consider it our responsibility to inform you about the limitations of your performance clothing.
The hollow fiber structure of yak and camel wool offers better insulation than any other wool when wet; our heavier knit takes longer to reach its moisture absorption limit, and the thicker wool fabric generates more heat through absorption. At a certain level of exposure to water, however, the insulating effect is significantly reduced or—in the case of a garment that’s dripping wet— completely exhausted, just as with any other material.
With our performance clothing, you delay the point at which the wool’s insulating power begins to diminish and reduce heat loss even when the fabric is wet. However, significant heat loss still occurs once the wool is saturated to approximately 80% or more of its own weight. At this point, heat dissipation from the damp wool outweighs the insulating effect of the hollow fibers and the heat released during absorption.
The good news: Our functional clothing is designed so that this situation almost never occurs, even during heavy sweating or hours of drizzle. This is what makes our functional clothing made of yak and camel wool unique.
HOW TO PROTECT YOURSELF FROM HYPOTHERMIA IN COLD, WET WEATHER
If you do happen to get caught unprepared in a heavy rainstorm or thunderstorm and don’t have a rain jacket on hand or a shelter to take cover in, here’s our advice: Don’t panic. Take off all your outer layers down to your yak wool base layer, scarf, and hat, and stow your mid layer and warm outer layer safely in your waterproof backpack. Now it’s best to pick up the pace.
Yak wool, like your body, is optimized for peak performance and capable of amazing things in a short time: The body heat released by rapid movement—which is effectively retained by the wool —and the heat absorbed by the wool upon first contact with water will often keep you warm until you’ve found a safe shelter. Once there, take off your soaked base layer and put back on your yak wool sweater or cardigan, which has stayed dry. It wicks away your body’s residual moisture and traps your body heat in its millions of air pockets, so you’ll warm up quickly and avoid hypothermia.
