What Makes Thermal Underwear Keep You Warm?

Snowy treetops, hot cocoa, and warm hugs are all the things that make winter worth it. Santa season comes with amazing opportunities to create new memories with your loved ones. From snowboarding to sightseeing in the mountains, you won’t run out of fun things to do. But to actually have a good time when temperatures drop, staying warm is essential. Needless to say, you don’t want to lose your toes to frostbite.

While a sweater might shield most of your body from the harsh wind, don’t be surprised if the cold still seeps through. To stay snug, take it up a notch with thermal underwear.

Thermal underwear insulates the body against low temperatures. All humans lose body heat during exertion, be it walking, sitting, or simply extending your arm to grab that hot cup of coffee. The second law of thermodynamics entails that heat transfers from warm to cold which is why sitting on a frosty bench in the winter is the last thing you want to do.

What Is Thermal Underwear?

Thermal underwear is usually made of wool or synthetics. Fibers within the fabric trap heat and slow down transfer to surroundings. Also, the right size of thermal underwear sticks to the skin and absorbs sweat to prevent evaporation. A cooling effect whereby body heat is rapidly lost to the air.

Compared to regular jeans and t-shirts, thermal underwear exhibits incredible heat retention capabilities. This largely has to do with the type of material used. Additionally, secure stitching also helps combat heat loss.

The Best Material for Thermal Underwear

Quality thermal underwear is a wise investment. If you live in harsh climates where it’s cold most of the year, feel free to buy a few. But when it comes to defining quality, the best thermal underwear is made of merino wool. The latter is thick, fibrous and natural. It makes for a great thermal base layer in leg warmers and thick vests. And although it might sound bulky, merino wool is lightweight, in that, even less than an inch of thickness goes a long way.

You can wear merino underwear to stay warm and exercise outdoors. This moisture-wicking fabric is great at drawing sweat away from the body. Besides functional perks, merino wool underwear is available in a variety of colors and patterns. Safe to say, you won’t have trouble finding something to match your taste. With darker shades, you can get away with irregular washing as well. Merino wool is pretty versatile and keeps well even without a daily spin in the washing machine.

That said, underwear made of merino wool is viewed as high quality, and can be rather expensive. So, if you’re thinking about saving a buck or two, perhaps go for synthetic polyester. Compared to other types of wool, merino is also slightly scratchy. As it is woven with natural fibers, people with very sensitive skin might need some getting used to its subtle roughness.

The Right Fit Matters

Now that you know which fabric to look for, pay attention to the stitching. Loosely fitted underwear might look bougie, but it also lets in a draft. Thermal underwear is meant to be worn as the first or second layer of clothing. If you’re thinking about dressing it down as a winter top with jeans, make sure it’s snug.