5 Things You Didn’t Know About Your Wool Sweater

The science is in—the natural properties of 100% wool out-performs synthetic textiles every time.

February 23, 2017
wool sweater
Plume Creative/getty

People have been wearing woolen garments, spun from the fleece of sheep, since prehistoric times. But unlike most other caveman fashion choices (hello, leather loincloths!), wool has remained at the core of how we garb ourselves, and it’s good for much more than getting cozy in wool sweaters and shawls.  Clothing manufacturers are making 100% Merino wool yoga pants and running wear—and for good reason.  Though it’s a low-tech, natural fiber, wool ranks right up there with any state-of-the-art performance fabric you can think of, thanks to wool’s natural properties.  Plus, wool’s a sustainable and biodegradeable fabric–and, if you care for wool correctly, it will last decades.

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sweating in wool
Wool Is Naturally Odor-Resistant

A 2007 study comparing how stinky different types of fabric can get, compared to polyester and cotton, wool was the least smelly after being worn. This is thanks to wools’ ability to absorb and evaporate quickly: Sweat itself doesn’t stink; clothes get stinky when bacteria metabolize sweat clinging to your garments. Wool is better than other textiles at quickly absorbing and evaporating sweat before odor-causing bacteria get a chance to break it down, meaning it doesn’t hang onto bad smells the way that, say, polyester does.  And unlike synthetic “anti-odor” clothing treated with antimicrobial elements like silver chloride, wool’s anti-stink properties don’t come out in the wash. 

Related: 6 Effective Solutions for Body Odor 

standing in the rain
roman makhmutov/getty
The Wetter Wool Gets, the Warmer it Feels

Wool feels warmer as it becomes wetter, thanks to a heat-generating chemical reaction between water molecules and the fiber’s core: as wool absorbs moisture from the atmosphere, it breaks water’s hydrogen bond, generating warmth.

Related: Do Your Best Darth Vader And 2 Other Breathing Tricks To Warm Up Fast

hiking in hot weather
Hero Images/getty
Wool Keeps You Cool in Hot Weather

Wool fiber pulls moisture toward the outside of the garment, keeping a layer of dry air—which acts as an insulator—between itself and your skin. The material can soak up 35 percent of its weight before you’ll feel damp. You might already know that this makes wool a superior material for cold-weather garments—but it’s also great for hot climates, where the fabric’s ability to dry your skin accelerates the evaporation of sweat and helps keep you cool.  Look for garments made of 100% ultrafine Merino wool–we like the Ibex OD Shanti shirt and the Smartwool NTS Micro 150 Tee.

Related: 8 Things Every Southerner Knows About Staying Cool During A Heat Wave 

falling asleep
Astronaut Images/getty
Wool Can Help You Fall Asleep Faster

University of Sydney researchers found that, in a 63 degree room, people wearing wool pajamas fell asleep 10% faster than those in cotton pjs, and also achieved deeper sleep for a longer period of time. Unfortunately, while there are tons of great kids merino wool pajamas and wool sleep sacks for infants and toddlers, no one seems to make merino wool pajamas for adults—try mixing and matching lighter merino wool base-layer pieces for a good night's sleep.

Related: 9 Foods Proven To Help You Sleep Better

Sönke Bullerdiek / EyeEm/getty
Wool Is Fire-Resistant

Because it holds moisture from the atmosphere, wool has a high water content. It also has a high nitrogen content, and these qualities make wool very difficult to ignite. It requires more oxygen and higher temperatures to ignite than cotton, rayon, polyester, or  acrylic to ignite (wool won’t ignite until 1,382 degrees Fahrenheit, while cotton burns at 491 and polyester melts at 485 degrees), and the structure of its fiber causes wool to self-extinguish once lit. This makes wool the best fabric to wear if you’re going to be hanging out by a campfire, but also the best for home furnishings like mattresses or carpets.

Modern homes—and the furniture in them—burn way hotter, and faster, than homes did 50 years ago. One of the main reasons is that furnishings that used to be made of natural fibers like wool are now made from petroleum-based materials that are quick to ignite. (And because those materials are so flammable, they’re heavily treated with flame-retardants, which are toxic—retardants can mess with your fertility, among other things. Read more about the truth about flame retardant furniture.)