Male Splitboarder wearing the Summit Base Layer

Cover Your Bases: A Guide to Base Layers

Your Guide To Base Layer Perfection

When it comes to getting after it in the outdoors, one essential piece of gear often overlooked is the base layer. A good base layer is the foundation of any cold-weather outdoor pursuit as it sets the stage for getting the most out of your day. Put simply, a proper base layer means your @ss is covered no matter what mother nature throws at you. 

Let’s dive into these hot topics and become base layer experts: 

  • What Is A Base Layer? 
  • What’s The Point Of Wearing A Base Layer? 
  • What Should You Look For In A Base Layer? 
  • What Can You Use Base Layers For? 
  • What’s The Best Base Layer Fabric?

What is a base layer?

    A base layer, sometimes called “long underwear” or “thermal underwear,” is the first layer of clothing that touches your skin. The best base layers are made from synthetic fabrics that are specifically engineered to provide insulation, moisture management, and temperature regulation. Let’s take a closer look at these three characteristics.


    When we talk about insulation from fabrics, what we’re really talking about is the fabric's ability to trap a thin layer of air and minimize heat transfer between your body and the surrounding elements. You want the heat to get trapped in, but you don’t want excessive sweating from overheating. This is where temperature regulation comes into play, which we’ll cover shortly. 

    Moisture Management

    We all sweat. Some people barely shed a drop while others can pour buckets just thinking about movement. No matter how much moisture you produce, the only way to stay comfortable and warm in the cold is to keep the wetness off your body. This is where moisture-wicking fabrics shine. 

    Moisture-wicking fabrics are engineered with water-repelling properties. This means they don’t retain moisture and instead encourage it to move to the surface of the fabrics where it can evaporate. This is why all BlackStrap base layers feature our Dri-Flo moisture-wicking system that keeps your sweat away from your skin allowing optimal temperature regulation. 

    Temperature Regulation

    Temperature regulation, also known as thermal regulation, refers to the fabric's ability to maintain a comfortable body temperature by actively managing heat exchange between the body and the environment. Essentially, thermal regulation is gauged on the fabric’s ability to insulate, breathe, and stabilize temperature at the same time. 

    BlackStrap base layers focus on thermal regulation by utilizing Ventra, a system of strategically placed panels of super-breathable fabric where your body generates the highest levels of moisture and heat. Combining Ventra across our various levels of insulating and moisture-wicking fabrics, creates the perfect recipe for all day comfort.

    What’s The Point Of Wearing A Base Layer?

    Wearing a base layer is like taking out an insurance policy on your epic day. Base layers help guarantee you can spend all your energy chasing the best times rather than wasting it trying to stay warm or cool. 

    Base layers also add versatility. When worn without a mid or outer layer, base layers bring insulating comfort while being extremely lightweight, breathable, and soft to the touch. When combined with mid and outer layers, base layers become the backbone of your clothing kit allowing you to easily shed layers and control your operating temperature without sacrificing your heat.

    What Should I Look For In A Base Layer?

    Base layers come in a gazillion different styles, colors, fabrics, and fits. The options can be daunting. At BlackStrap, we’ve put our decades of experience in the mountains to work by creating the most well-rounded, highest-performing base layers on the planet. Over the years we’ve learned that versatile fits, a next-to-skin  feel, and UV protection are the most important qualities our outdoor-centric customers look for in their base layers. Let’s dive into these further.

    Versatile Fit 

    From burning legs to après, being comfortable in your environment is paramount to crushing the day. Your base layer fit should be snug enough to lock in your body’s heat, but not so tight that it hinders your mobility or makes you feel uncomfortable. The key here is 4-way stretch fabrics. By meticulously blending in perfect amounts of elastic into synthetic fabrics, we’ve been able to produce 4-way stretch thermally regulated fabrics that articulate and bend so naturally they feel like a second skin.

    Second Skin Feel

    With base layers being next to your skin, you want a material that will play nice with both dry and moist skin conditions. Cotton is soft, but it acts like a sponge and becomes sticky and cold once it traps in water. Wool performs better than cotton, but it doesn’t always play nice with sensitive skin and other layers. This is why we prefer synthetic fabrics with brushed finishes. By “brushing” the inner side of the fabric, we’re able to create a very soft, smooth feel that doesn’t stick or itch no matter how hard it’s used.

    UV Protection 

    Spending time in the mountains means mother nature is pelting you with even harsher UV rays than at lower elevations. In fact, studies by super smart people have shown there’s a 6 to 10 percent increase in UV exposure for every thousand feet of elevation gain. That means if you’re riding at 6,000 feet, your UV exposure is 36 percent higher than at sea level! 

    One major benefit to wearing base layers made from synthetic fabrics rather than wool is that you can engineer them with built-in UV protection. For example, all BlackStrap fabrics feature SpectraUV, a sun-blocking technology that offers the highest rating possible, UPF 50+.

    What Can You Use Base Layers For? 

    This may sound like a big claim, but it’s our humble opinion that when you find the perfect base layer, you can wear them just about anywhere, anytime. While they’re specifically designed to outperform in cold mountain climates, BlackStrap base layers can be worn for any active or inactive pursuit. From walking the dog, hiking mountains, to lounging fireside after a long day of shredding, when your base layers are more comfortable than pajamas you will struggle to take them off long enough to wash. The good news is that all BlackStrap base layers feature odor-fighting properties so the laundry can wait a little longer than usual.

    What’s The Best Base Layer Fabric? 

    There are three main types of fabrics used in base layer manufacturing; cotton, wool, and synthetic. Cotton is less than ideal due to its water absorbing properties and lack of breathability. You’ll typically only find cotton used in inexpensive, mass produced base layers. Wool works well, especially merino wool, but it’s limited in its ability to stretch. Wool does a good job at fighting odor, but can sometimes cause itchiness on more sensitive skin. We’ve found synthetic fabrics to offer the best balance of comfort and performance due to the ability to engineer specific properties in each fabric. For instance, we’ve developed three proprietary fabrics that are each designed to offer specific qualities. Let’s take a look.


    EXTEN is our lightest weight base layer fabric. We’ve designed EXTEN to offer maximum amounts of moisture wicking and quick-dry features. This is the perfect fabric for those who run hotter than most or are looking for a base layer to kit with multiple other layers. EXTEN is our go-to on warm spring days with its lightweight, UV blocking characteristics and works flawlessly in both on and off snow outdoor pursuits. You can find EXTEN on all Skyliner & Pinnacle Base Layer styles.


    The industry standard for midweight perfection, VERSA fabric technology perfectly balances optimum maneuverability and thermal regulation to perform in all conditions. This is our daily-driver. From opening day to last chair, VERSA is the people's champ of base layers. You can find VERSA fabric technology used in all Summit & Cloudchaser Base Layer styles.


    When the coldest temps set in, THERMA steps up. Meticulously developed with an extra soft brushed finish and slightly thicker than our other fabrics, THERMA performs when everyone else gives up. Loved for its ability to lock in all the heat your body can produce, this is the fabric you need if you love getting after it in sub-zero temps. THERMA technology can be found on all Therma Base Layer styles.

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