The Definitive Buyers Guide: How to Choose Base Layers

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We all know the importance of shelter and food when you’re backpacking or hiking, however, clothing is also a crucial component to keeping yourself safe and warm.

If you’re hiking and you’re feeling a tad chilly, you can fix that without having to start a fire or put on a warmer jacket. Even if you’re feeling cold at home or at the office, there’s no need to grab a blanket or stand by a fireplace. All you need is a durable and efficient base layer.

Now, you may be thinking about how you’re going to find a base layer and which one you should pick. As we all know, there are hundreds of different companies offering base layers, so it can be an overwhelming task.

However, in this article, we’re going to discuss the basics of a base layer so that when you look for one, you know exactly what you need.

When deciding on a base layer, you’ll need to consider these factors which we’ll discuss further on:

Fabric Weight

Base layers come in three weights: lightweight, midweight, and heavyweight.

Merino Wool vs. Synthetic

There are different fabrics which serve different purposes.

Weather

Knowing roughly the type of weather or season you’ll be in will help you narrow down your options.

Your Activities

You’ll be choosing a weight and fabric based on your needs, whether you’ll be casually walking, running, skiing, etc.

What Do Base Layers Do?

Naturally, you’ve heard of base layers but you probably thought it was a waste of your money to invest in one. Why get a base layer when you can just throw on an extra jacket or sweater?

However, perhaps you just don’t know the function of a base layer. The concept of the base layer is to regulate your body’s temperature and push moisture away from the skin while you’re being active.

It protects your skin by acting like a second layer, which comes into contact with the mid-layer or outer-layer.

Base layers such as long underwear are able to trap in heat. Many people assume that base layers are only needed for those camping or backpacking, but that’s not the case.

You’re able to wear base layers under anything. You can wear a pair of long underwear under jeans on a cold day or under your running outfit. The point is since they act like a second layer of skin, it doesn’t matter if you wear them when you’re active or while you’re sitting at the office. They’ll hardly noticeable while you’re keeping warm.

The most important factor of the base layer is the wicking process as that’s what actually keeps the moisture away from your skin. By moving the moisture to the outside of your base layer, it’ll spread among a larger surface which is what causes it to dry quickly, thus, keeping you dry.

If you were to wear a couple of sweaters instead of a base layer, you’d be sweating and the moisture wouldn’t be going anywhere.

Lastly, base layers work to control the temperature. If you’re exposed to cold weather for a long period of time, you become susceptible to injury. This is because your muscles become weak.

However, base layers are designed to keep your core muscles warm. But at the same time, base layers can also work to keep you cool. There are a variety of loose-fitting, lightweight materials which focus on evaporating moisture from your body but also promoting airflow to keep you feeling cool.

What Happens When You’re Not Properly Dressed?

Now, you know what a base layer does but is it really important to wear them if you’re not going to be mountaineering? Surely you can go without them during the fall or spring season, right? Wrong.

Unless you’re in the hot summer heat and want to be shirtless, if you’re planning on any outdoor activity such as hiking or backpacking, you need to wear a base layer.

For example, both hot and cold temperatures place a major physiological stress on the body. Naturally, the more healthy and fit you are will better protect you against these stresses, however, even if you’re the fittest person on the planet, you need to wear a base layer.

Dressing properly is the key component to keeping you healthy while you’re outside as it’ll reduce the number of physiological stresses your body will experience. This is specifically important for people who aren’t acclimatized to the cold or hot climates.

Many people travel around the world, putting themselves into completely different climates which means they must be prepared. Without a base layer, you’re making yourself vulnerable to some of the dangers related to temperature.

Hypothermia

This condition occurs when the body’s temperature goes below 35 degrees Celsius. What happens is that your body is losing more heat than it makes. This typically happens when you’re exposed to cold weather or water. Hypothermia can be identified as shivering, confusion, tiredness and a lack of balance. If not treated promptly, hypothermia can cause severe health problems.

Heat Exhaustion

This is caused when the body loses a large amount of water from excessive sweating. It can interfere with brain functions, causing heart, kidney, and lung failure.

Frostbite

This occurs when cold temperatures damage body parts. Most specifically, frostbite typically affects ears, chin, fingers, toes, nose, and cheeks. Usually, areas which aren’t protected. The body part will have problems with mobility and the skin will turn black.

Heat Stroke

This occurs when the body in exposed to long periods of heat and is unable to cool itself. Base layers can help regulate the body’s temperature in moments like this.

Heart Conditions

If you’re in cold weather and you’re not properly protected, you’re exposing yourself to potential heart conditions such as a heart attack. When you’re exposed to cold weather, your heart is working extra hard in order to help keep you warm. By doing this, this increases your heart rate and blood pressure which is a red flag for a heart attack.

Colds and Flu

Now, it’s important to understand that colds and the flu are not caused by the cold weather itself. What it’s caused by is by contact with others. It’s a common myth that people contract illnesses and viruses via being wet and cold. However, there is a connection. Humans are more susceptible to viruses during the winter months because the immune system is reduced. To prevent colds and the flu, you must keep your body warm in order to reduce the chances of you catching a virus.

Asthma

Cold air is able to trigger asthma attacks and the only way to avoid this is by avoiding cold air. Now, if you’re an outdoorsy type, this isn’t going to be easy. However, that doesn’t mean you can’t go outside. Instead, you just need to dress appropriately. Meaning, you need to keep your mouth and chest covered.

Being cold isn’t fun and if you’re not dressed properly, you can get yourself into more problems than necessary. So, with knowing the importance of wearing a base layer, it’s time you learned what comprises a base layer and what to look out for.

How Should Your Base Layer Fit?

In order for base layering to work effectively, you need the fabric to lay against your skin which will aid in picking up the moisture. Remember, wicking is one of the most important factors in base layering in both cold and hot climates. To make sure your base layer is working, you need it to fit snug against your body. Though, depending on your activity, you may want a more loose-fitting base layer for increased airflow.

Now, you may be wondering what you should do if you have various activities which all have different requirements. For example, you may want more airflow when running, however, when backpacking, you want to focus on wicking. Well, there are a couple of different types of base layers to choose from. Base layers can come in a variety of shapes, sizes, and weights which will suit different activities and temperatures.

Base Layer Weights

Like we said before, base layers aren’t cookie cutter in design. Instead, they come in a variety of shapes, sizes, and weights. The variety suits an array of activities and temperatures that you may participate in.

Lightweight

Rule of thumb: the lighter the material, the better at wicking and drying. As a lightweight base layer, it will excel at moisture-wicking and drying. Most athletes who are outside prefer a lightweight base layer as it rests against the skin, absorbing the moisture. Though, what it does for wicking, it lacks in insulation. For example, a skier will use a lightweight base layer under a midweight or heavyweight layer. It’ll fit snug against the body which is ideal for moisture-wicking, as it’s designed to be a part of a layering system. However, you can also wear a lightweight base layer as a piece on its own if you’re going to be in mild to cool conditions if you’re moderately active.

Midweight

These are typical bases which act as a next-to-skin layer. However, they can also act as a second layer over the top of a lighter material. They provide you with both moisture wicking and insulation. They accompany well into layered outfits as they also provide a decent amount of protection against cold temperatures during moderate levels of activity.

Heavyweight

You can tell by the name that this weight of base layer means business. Heavyweight materials are specifically designed for cold climates regardless of how much physical activity you’re enduring. You can be sitting or running a marathon in the snow, but it’s meant to keep you warm. A heavyweight isn’t typically worn as a first layer, rather, they’re usually worn with lighter materials as well, giving it more insulation. They’re not ideal for wicking away moisture as they’re not designed for this purpose. Heavyweight materials are usually thick in nature and are worn loosely on the body.

Base Layer Size

So, how are you going to wear your base layer? It depends on the weight you decide to go with, however, a base layer is typically tight fitting so that it picks up the moisture and insulates you. It’s best, when trying them on, that you choose a base layer of a size that you normally wear since they’re designed slightly smaller than regular sizes.

Base Layer Types & Materials

Different fabrics work in different ways regardless of the garment. In the case of base layers, different fabrics work to keep your body at an optimal temperature whether you’re out in the cold or exercising outside. Generally speaking, synthetic fabrics and merino wools are the most commonly used materials for base layers, however, there are a couple of others that we will feature as well.

Traditionally, stay away from cotton as it makes a poor fabric for base layers. Cotton soaks up moisture and takes away heat from the body. This leaves the body cold and highly uncomfortable.

Synthetic Base Layers

Synthetic base layers are typically made of polyester and polyester blends. The base layers are designed to focus on keeping the individual warm in temperatures as low as -8 to -10 degrees Celsius. Polyester base layers dry extremely quickly and are lightweight which is ideal for wicking moisture away from the body. Here are some of the pros and cons of synthetic base layers.

Pros

  • Quick drying
  • Machine washable
  • Lightweight
  • Inexpensive
  • High wicking
  • Cons

  • Not as warm as merino wool
  • Not antibacterial
  • Merino Base Layers

    Merino wool is one of the most common materials used in base layers. Merino wool helps regulate the body’s temperature with the tiny air pockets in the wool aiding in removing excess heat from your body, preventing overheating. Merino wool is ideal if you’re going to be undergoing vigorous exercise. At the same time though, Merino wool also works to keep the heat in, making sure that you are kept warm during cold weather. Merino wool can keep you warm in temperatures as low as -15 to -20 degrees. So, it’s a great option if you’re going to be using it in different types of weather, whether it be hot or cold.

    Merino wool is naturally UV resistant, so, if you’re in the sun or up in the mountain skiing, you’ll be protected. They’re a wonderful base layer if you need to retain heat even if you’re wet. So, if you’re in the mountains surrounded by snow, you’ll be sure to be kept dry and warm.

    In addition, Merino wool has natural antibacterial and wicking properties which not only keeps your skin dry but also healthy. Here are some of the pros and cons of Merino wool base layers.

    Pros

  • High wicking
  • Natural UV resistance
  • Warmer than synthetic materials
  • Retains thermal properties when wet
  • Naturally antibacterial
  • Soft against skin
  • Breathable
  • Cons

  • Doesn’t wick as well as synthetic materials
  • More expensive than other fabrics
  • May not be machine washable, depending if it’s made of 100% wool or not
  • Bamboo Base Layers

    Bamboo base layers are a pretty new concept, so not all brands are offering this material, however, you’ll be able to find speciality brands that have bamboo base layers. They’re made from bamboo extracts that can sometimes be mixed with Merino wool, cotton, or Lycra. Now, bamboo base layers typically fit tighter than pure Merino wool base layers and they also hold their shape much better than other fabrics. In addition, if you’re sensitive, bamboo is extremely soft and will not irritate your skin in comparison to Merino wool. Here are some of the pros and cons of bamboo base layers.

    Pros

  • Anti static
  • Quick drying
  • Fits closer than merino wool
  • Eco-friendly
  • Antibacterial properties
  • Less expensive than Merino wool
  • Resistant to abrasion
  • Ideal for sensitive skin
  • Cons

  • Not easily available
  • Quality varies between brands
  • Silk Base Layer

    Silk isn’t that popular but it’s available on the market. It’s usually treated with chemicals to increase the moisture wicking features. Silk is ideal for colder temperatures, plus, if you have sensitive skin, it’s extremely soft and smooth. It’s best for those going into cold temperatures and aren’t looking for skin irritation. Here are some of the pros and cons of silk base layers.

    Pros

  • Thin and lightweight
  • Ideal for sensitive skin
  • Wicks moisture
  • Made of natural fibers
  • Cons

  • Can shrink if not properly washed
  • Hand washing typically required
  • Not as durable as synthetic materials
  • Weather

    When it comes to attire, regardless of the season or activity, we always dress for the weather. When you’re outside, you need to use the weather as a gauge for the way you dress. Traditionally speaking, the colder the temperature is, the higher the warmth factor you need to aim for. Make sure you look at your own body temperature as well. If you’re usually hot, then you may not need a high insulating base layer. Whereas if you’re typically cold, then you’ll need a heavier base layer to keep you warm.

    You may not be sure what type of fabric you need your base layer to be when it comes to the activity you’re doing. However, don’t worry, we covered this for you. Below, we talk about the types of activities and base layers you’ll be needing to properly support you.

    Activity Level and Your Base Layers

    Sometimes it’s easier to choose a base layer in relation to the type of physical activity you’re going to be doing if you’re not sure about the weather. Maybe you like long hikes or working out at the gym. Regardless of what you like to do, it’s a key component when figuring out the best layering choice for you.

    Naturally, materials are important and will influence the base layer you go with, however, there are some fabrics and weights which are best for specific activities.

    Low-output Activities

    When it comes to low-output, relaxed activities, it’s best if you choose merino layers as you won’t necessarily be building up a sweat. These type of activities include travel, camping, urban cycling, hanging out or calm day hikes. They’ll be able to keep you toasty and warm throughout the day.

    Casual Hiking

    When you’re casually hiking, you’re most likely doing it in moderate temperatures and at an even pace. This means that your base layer should be snuggly fit and warm. You can use basically any material in this case, aside from cotton. Bamboo is a great material which will provide you with comfort and protection. Silk isn’t a bad option, however, it lacks moisture-wicking abilities. Synthetic materials will offer you comfort, moisture-wicking, and warmth as well.

    High-output Activities

    For moderate to high-level activities you’ll want these layers to support you during your sweatiest of times. Focus on synthetic layers which will focus on moisture wicking rather than warmth. Synthetic materials will work to push the moisture away from your body, allowing you to dry off quickly.

    Extreme Adventures

    When you’re taking part in extreme activities, you’re going to want to opt for odor-resistant materials. Whether it’s climbing or hiking for long periods of time, it’s going to produce sweat. When this happens, you’re going to want natural materials such as Merino wool which is designed to provide you with natural odor resistance as moisture absorption. Merino wool is thick yet highly breathable which will support you in keeping dry.

    Backpacking

    When you’re going backpacking, you need to find a base layer which best suits the activity, Though, you need to find a fabric which matches the type of backpacking trip you’re going on. If you’re going to be experiencing multiple climates then you’ll need a material which can adapt. In this case, you can choose either wool or synthetic fabric. Your backpack is going to trap in the heat and sweat regardless of the fabric properties. So, instead of focusing on that, instead, focus on comfort and weight. Merino wool can absorb moisture without it feeling wet.

    Upper body Activities

    When you’re using your upper body, for example, when you’re climbing or rowing, you use a lot of those muscles which lead to a lactic acid buildup in your muscles. This build-up in your muscles causes swelling. So, for your base layer, you’re going to want to opt for a loosely fitted garment with thicker fabric. You can choose wool or synthetic materials which will also provide you with protection and moisture-wicking properties.

    Recreational Snow Activities

    Any activity which makes you go through tough landscapes means you’re going to be sweating and burning more calories, thus, you need to stay warm. If you’re going to be skiing or snowshoeing then you need to wear a minimum of two layers which you’ll either add on or remove throughout your activity. Though, you should always keep at least one layer on at all times, preferably Merino wool as it’s thick and warm. Then, your second layer can be either Merino wool or synthetic fabric.

    Do you have to treat a base layer differently than your other garments? Is there a specific way to care for them? You need to know these answers as proper care will help the longevity of your base layers.

    Fabric Care

    Regardless of the fabric, if you want them to last, you’re going to need to take care of them. In the case of base layers, it isn’t any different. Now, depending on the fabric, the way you care for it will vary.

    Silk

    Silk is extremely fine and delicate which means you’re going to need to take particular care in washing and caring for it. It will require you to hand wash it. If you machine wash it, you run the risk of shrinking it.

    Synthetic

    This material isn’t odor resistant, unfortunately, which means you’re going to need to wash it on a regular basis. The great thing about synthetic fabric is that you’re able to machine wash it without any trouble. Though, if it’s chemically treated, make sure you’re not using harsh detergents as it could damage the coating/finish. One thing is for certain, you should always hang-dry them.

    Merino Wool

    It’s a little trickier than the others, however, it’s versatility makes up for the challenge. Merino wool must be washed in cold water in order to prevent shrinkage. Keep your Merino wool away from any harsh detergents, bleach or fabric softeners. To dry Merino wool, you need to hang-dry the garment if you want to make sure it keeps its shape and size.

    What Do you Wear After the Base Layer?

    You’ve become an expert about base layers but now, you’re not sure what to wear after the base layer. That’s a good question that you should be asking. A base layer isn’t going to be enough, but there’s a way to layer intelligently. Here’s how to do it.

    Base Layer

    You know all there is to know about base layers. They’re the layer which comes in direct contact with your skin. Its main purpose is to remove and push moisture away from your skin and to the surface of the fabric. You’ll be wearing this as your first layer.

    Mid Layer

    This is the layer that adds insulation and traps body heat in order to keep you warm while also pushing the moisture away from your body. You should opt for fabrics such as fleece as it helps insulate without making you feel bulky while also allowing moisture to pass through. Other mid-layer options are lightweight garments which are also insulated. Your mid-layer should be roomy enough so that you can comfortably wear your base layer underneath and move freely.

    Outer Layer

    This is your final layer and is also called a “shell”. The shell protects you from the elements. You’ll want to choose your shell based on the climate as some areas will be windier or rainier than others. Though, regardless of the weather, you should aim for a shell that’s breathable, allowing the moisture to pass through. Your outer layer should also fit loosely around your base and mid-layer, so that you can move with ease.

    To keep your base layer safe and protected from the elements, you need to make sure that your outer layer or also known as “shell” is properly protected. You’ll want to make sure your outer layer has the right features.

    Waterproof and Breathable Outer Layers

    If you’re looking for an outer-layer that’ll take you through both snow and rain, then you’ll need a hardshell. These fabrics are designed to protect you from whatever weather you encounter. A waterproof and breathable outer layer is usually bonded with a 2-layer, 2.5-layer or 3-layer construction. These layers will usually come with a durable water repellent (DWR) coating and seam taping which ensures that no water will seep through.

    Softshell

    You should look for an outer layer that’s soft shell. These outer layers are highly versatile as they’re typically warm, lightweight, and water-resistant. Your outer layer should have proper breathability with enough stretch to feel comfortable when you’re wearing a base and mid-layer underneath. However, soft shell layers do not give you the same protection as jackets do, so, don’t rely on a soft shell layer to protect you in the snow.

    Insulated Outer Layers

    If you have an outer layer that comes with built-in insulation, then it’s designed for specifically cold conditions. The thing about insulated outer layers is that they’re not very versatile. But then again, if you’re looking for an insulated base layer, then your main concern is about being kept warm. They tend to be heavy in comparison to a softshell, however, there’s no perfect outer layer. If you’re active, you’re going to need a jacket that’ll provide you with enough warmth without weighing you down.

    There are a couple of extra features to look for when deciding on an outer layer. If you want your base layer to be able to wick away moisture, then your outer layer is going to need to be able to support the base layer. Here are some features that’ll help make you feel more comfortable.

    Ventilation Zippers

    Ventilation zippers are a must-have feature on your outer layer if you’re going to be engaging in high-output activities such as hiking, mountaineering, and cycling. These activities are going to make you hot and sweaty. Your base layer is going to work hard to push the moisture away from your body, however, your outer layer needs to help continue the moisture-wicking process. The outer layer is usually made with a waterproof membrane which will work to move the moisture out of your jacket. Ventilation zippers help to push the cool air inside your jacket. These zippers are located where they matter: armpits, chest, and back.

    Pockets

    Once you get acquainted with outer layers, you’ll soon realize that the types of outer layers are easily identifiable by the pockets. Casual outer layers will have many inner and outer pockets for daily storage of personal items. Rain jackets will have pockets which are set higher on the body as they’re designed for climbing and hiking. Outer layers for snow activities have specialized pockets which are lined to protect your personal items. Lastly, outer layers for cycling typically come in minimal to no pockets to reduce weight and bulkiness.

    Hood

    Most outer layers will come with a hood. However, the type of hood you need will depend on the weather you’ll be in. Casual outer layers have basic hood adjustments whereas hiking outer layers come with adjustable hoods, typically with a stiffened brim. Outer layers for snow activities such as mountaineering or skiing will come with large hoods that can support a helmet. Lastly, the outer layers for cycling will rarely offer a hood as they can block your vision. Aside from protecting your head from the elements, hoods retain heat as well, keeping you warm where you lose the most heat.

    These extra features all play a role in moisture wicking and heat retention. However, you want to make sure that at the end of the day, you feel comfortable in your base, mid, and outer layer. If you’re finding your movement restricting, then you need to make sure you chose the right outer layer. If not, it can affect your base and mid-layer.

    Final Thoughts

    When it comes to the great outdoors, you need to wear the right clothes. After reading this article, you now know how important it is to be properly layered, however, more importantly that you choose the right type of base layer for your needs. Whether you’re backpacking, hiking or camping, it’s important to really focus on the climate, fabric, and weight of your base layer. In addition, it’s also a necessity to choose a mid-layer and outer layer which fits with your base layer and makes your movements easy. Once you put all the pieces of the puzzle together, you’ll be well prepared to take on the great outdoors.


    Now that your base layers are sorted for the cold outdoors, how about your sleeping bag? Check out my guide to the Best Cold Weather Sleeping Bags.

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