A baselayer is the first layer of clothing worn directly against the skin. Also known as thermals or polyprops, their primary purpose is to regulate your body temperature and manage moisture — keeping you warm when it’s cold and cool when it’s hot. They are usually breathable, lightweight, quick-drying, moisture-wicking and odour-resistant, which means they can be worn day after day on gruelling outdoor missions. Your baselayers are more than items of clothing — they’re also vital pieces of safety equipment. They are crucial for keeping your core at a suitable temperature and moving sweat away from your body where it can dry quickly on the surface of the fabric. For this reason, it’s important to choose baselayers designed for the outdoors. The most common baselayer fabrics are natural Merino wool and synthetic alternatives, such as polyester and nylon. The most commonly used baselayers are short sleeve t-shirts, long-sleeve t-shirts, leggings (or long johns), and underwear (singlets and boxers). SHOP BUSHBUCK BASELAYERS

You might be wondering if baselayers or thermals are needed for all outdoor activities. Baselayers are highly recommended if you are expecting to:

• Work up a sweat

• Be exposed to cold/hot weather

• Experience temperature changes (including different times of day)

• Encounter scrub, bush, or rugged terrain

So, if you’re just going for a short one-hour loop walk in a sub-alpine forest or local park, you probably don’t need high-performance baselayers. But there’s no reason why you can’t wear them for all outdoor activities.

Let’s dive into everything you need to know before buying baselayers or thermals for your next adventure.

Weather Conditions

I think the first thing to consider is: What weather will you likely be exposed to? This helps you to have a clear idea of the weight, warmth, and features to look for right from the outset. I think the easiest way to break this down is by looking at the best baselayers for each season.

SUMMER BASELAYERS

If you think you’ll do most of your adventuring in the summer — or close to sea level (not in the mountains) — then you will want to look for lightweight, breathable, cooling baselayers. The lighter fabric makes it easier for heat and moisture to escape, keeping your body temperature comfortable in summer conditions. There are some baselayers that have natural cooling properties, such as the Bushbuck Apex range, which is made with bamboo charcoal-infused honeycomb fabric. A short sleeve tee is probably the best base layer for summer, but if you’re worried about getting blasted by the sun, a long sleeve baselayer will provide more UV protection. You may also want to consider boxers or briefs that are breathable and moisture-wicking because we all know how hot and sweaty it can get down there when hiking or hunting in the summer. If you’re planning to venture into the alpine zone during summer, you may want to consider getting a heavier baselayer to provide extra warmth, especially for the mornings and evenings at the hut or campsite.

SPRING/AUTUMN BASELAYERS

Weather during the shoulder seasons of spring and autumn can be unpredictable, ranging from hot and sunny to wet and blustery. You could either go with a midweight baselayer, suitable for most weather conditions, or you could carry one lightweight summer baselayer and one heavier winter baselayer. 

The Bushbuck Combat Merino Tee is a versatile option for Spring and Autumn missions. Our CoreTech Thermal range is a more entry-level “polyprop” baselayer for everyday adventures.

WINTER BASELAYERS 

If you’re planning on heading outdoors during winter, you’ll likely be exposed to freezing temperatures and wild weather, especially in the mountains. For winter missions, you’ll want to go with a heavyweight thermal baselayer that delivers plenty of warmth while still being breathable and moisture-wicking — because you can still work up a decent sweat in the cold. You’ll also want to have an effective layering system suitable for winter conditions. For winter adventures, I recommend the Bushbuck Combat Merino Half-Zip or Combat Merino Hood.

Baselayers and thermals are available in different weights. Similar to the insulation you put in your house, the thicker (or heavier) it is, the better thermal performance it will have. However, better thermal performance is not always what you want with baselayers — especially if you tend to run hot or you’re exploring in summer. Clothing weight can generally be determined by a measure known as GSM (grams per square metre). The higher the GSM, the heavier and thicker the garment. Most clothing items should have the GSM displayed on the tag or online. Without getting too “weighed down” by complicated numbers and measurements, you can think about baselayer weights in terms of: Lightweight, midweight, and heavyweight.  LIGHTWEIGHT: Around 120gsm to 150gsm. It should feel light enough to wear in the sun or to the gym. MIDWEIGHT: Around 150gsm to 200gsm. It should feel warm and comfortable without restricting movement. HEAVYWEIGHT: Above 200gsm. It should feel seriously warm, but the weight and thickness may be slightly restrictive. As a general rule, the heavier, thicker and warmer your baselayer is, the less breathable it will be — so there are always trade-offs to consider. Unless you are expecting to encounter sub-zero alpine conditions, a midweight baselayer should be sufficient for most situations.

This might be the most common question we get about baselayers: Are merino or synthetic thermals best? Unfortunately, there’s no one-size-fits-all answer to this question. It entirely depends on which features matter most to you and how they feel against your skin. So, merino or synthetic? Let’s weigh-up the pros and cons.

MERINO BASELAYERS

Merino wool, sourced from Merino sheep, has long been revered for its natural properties that make it an excellent choice for outdoor enthusiasts, but it’s not without its downsides.

MERINO THERMALS PROS

• Temperature Regulation: Merino wool has a unique ability to regulate body temperature, keeping you warm in cold conditions and cool when it's hot. Its natural crimp creates tiny air pockets that trap heat, providing insulation without bulk.

• Moisture Management: One of merino's standout features is its moisture-wicking properties. It can absorb up to 30% of its weight in moisture while still feeling dry to the touch, making it ideal for staying dry when the going gets tough.

• Odour Resistance: Merino wool naturally inhibits the growth of odour-causing bacteria, keeping you feeling fresher for longer. This makes it a great choice for multi-day adventures.

• Comfort and Softness: Merino fibres are exceptionally fine and soft against the skin, which makes them less itchy than traditional wool clothing and comfortable for extended wear.

• Natural Material: The fact that Merino wool is a natural product is a major reason why it’s so popular. The demand for natural, ethically-sourced clothing is only increasing and Merino is the only natural fabric that has the performance features needed for outdoor adventures.

MERINO THERMALS CONS

• Lacks Durability: Baselayers made from 100% merino wool have one major downside: They’re not very durable. Hardcore hunters and adventurers often find merino wool thermals don’t hold up well in rugged environments, under the weight of a heavy pack, or even in the washing machine. Merino can be made more durable by blending it with other fabrics. Check out our durable merino thermal range

• Expensive: Merino thermals are more expensive due to the labour-intensive harvesting and processing of natural fibres, limited supply, and premium quality and performance attributes. Additionally, the sustainable and ethical practices associated with merino wool production contribute to its higher cost.

SYNTHETIC BASELAYERS

Synthetic fabrics, typically made from materials like polyester or nylon, have gained popularity for their performance-driven attributes. Here's why synthetic baselayers might be the right choice for you:

SYNTHETIC THERMALS PROS

• Quick-Drying: Synthetic fabrics have comparable moisture-wicking properties to merino, but may have the edge when it comes to quick-drying properties.

• Durability: Synthetic baselayers are known for their durability and resilience, retaining their shape and performance even after repeated washings and rigorous use. They are less prone to pilling and abrasion compared to merino wool.

• Affordability: Synthetic baselayers are often more budget-friendly than their merino counterparts, making them an attractive option for those looking for high-performance gear without breaking the bank.

• Versatility: Synthetic fabrics are engineered to offer specific performance attributes, such as stretchiness for freedom of movement or UV protection for sun exposure. This versatility allows you to choose a baselayer tailored to your specific outdoor activities.

SYNTHETIC THERMALS CONS

• Stinky: The main criticism of synthetic baselayers is they don’t have natural odour-resistant properties, so they can start smelling after a few days of sweating in them. 

IS MERINO ITCHY?

Merino wool fibres are much finer and softer than traditional wool, which makes them much less itchy and aggravating to bare skin. However, it’s true that some people do find merino thermals itchy or uncomfortable. Everyone’s skin sensitivity is different so if you’re concerned about potential itchiness, give merino a try before committing to it. Otherwise, synthetic baselayers might be best for you.

BEST OF BOTH WORLDS: DURABLE MERINO CLOTHING

These days, you don’t have to choose between merino and synthetic baselayers. You can get merino-synthetic blends that have the natural qualities of merino with some of the benefits of synthetic materials.  At Bushbuck, we’ve really been pushing the limits when it comes to designing baselayers that are built for the rigours of the outdoors. Our Combat Merino range is 52% merino wool and 48% durable nylon so you can enjoy the best of both worlds. It’s been independently tested to be significantly more abrasion-resistant than regular merino. Our Apex Baselayer range also combines the natural properties of bamboo charcoal with a synthetic honeycomb fabric to create a hybrid baselayer with anti-odour properties.

Next to warmth, moisture-wicking is probably the most important feature to look for when buying baselayers. 

Moisture-wicking fabrics are engineered to draw sweat away from the skin to the outer surface of the garment, where it can evaporate more quickly. This helps to keep your body dry and at a comfortable temperature.

This is why cotton t-shirts are not suitable or safe baselayers for outdoor adventures. Cotton absorbs sweat and holds moisture. As soon as the temperature drops or the wind picks up, it’s going to feel like you’re wearing a refrigerator. Things can get very uncomfortable very quickly.

Merino thermals and synthetic baselayers have excellent moisture-wicking properties.

Baselayer Styles

The style of thermal you choose isn’t just about how it looks, but also how it performs. Here’s a quick guide to some of the most common styles.

• Baselayer T-Shirt: The classic, no nonsense thermal tee is a must-have item. It can be used year-round, just make sure you’ve got a mid-layer to wear over the top in winter.

• Baselayer Long Sleeve: The longsleeve tee or crew thermal provides a bit more warmth and sun protection than the classic t-shirt. Long sleeve thermals also tend to be made from heavier fabric so they’re a good option for cooler weather.

• Baselayer Quarter-Zip: The quarter-zip or half-zip thermal is a versatile option for cooler weather. It’s like a long sleeve tee with a slight turtle neck for extra insulation. However, the zip allows you to offload heat when you get too warm.

• Baselayer Hood: The thermal hoodie is like a long sleeve tee and beanie in one. The hood is great for retaining warmth. Some baselayer hoodies also have a zip for managing your temperature on the go.

• Baselayer Leggings: Leggings or long johns are for keeping your legs warm in cool weather. They can be worn under shorts or pants. Hiking leggings are a more lightweight, flexible alternative to hiking pants.

Baselayer Underwear: Synthetic or merino boxer shorts are good options for managing your moisture and temperature around your nether regions. They’re generally more comfortable (and less smelly) than cotton underwear, especially on longer trips.

When shopping for thermals, price is probably one of the biggest factors for most people. We all know good quality outdoor gear isn’t cheap, but how can you get the best bang for buck when choosing your baselayers. AFFORDABLE: The tried and true synthetic polyester baselayer — known as the polyprop — is the most affordable thermal you can get. It does the job in most conditions. It will provide insulation, wick moisture, and breathe. But what you see is what you get. MID-RANGE: Synthetic blends are probably the next most affordable option. They usually use polyester blended with another material to improve some aspect of performance. It could be elastane for more flexibility; bamboo charcoal for improved breathability and moisture wicking; or some kind of odour-resistant material. Mid-range baselayers may also have more complex designs, such as mesh underarm sections, zips, pockets, or thicker fabric in high-wear areas. HIGH-END: Merino wool thermals are the most expensive baselayers, but like most things in life, you do get what you pay for. As we’ve discussed, Merino has natural properties that make it almost perfect for hiking baselayers. If you can find durable merino thermals, then merino really does tick all the boxes.

The Best Baselayer for Your Next Adventure

Choosing the right baselayer for your outdoor adventures can be a game-changer — you don’t want to take this decision lightly. At the end of the day it all comes down to balance — finding that perfect fit that hugs you just right, keeps you toasty when the mercury drops, and wicks away sweat when the going gets tough. This isn't just about staying comfortable (though that's a big part of it); it's about making sure you can push further, climb higher, and explore longer. The ideal baselayer is your armour against the unpredictability of the wild. So, as you gear up for your next adventure, take a moment to consider what lies beneath. Choose wisely, and you'll find yourself not just enduring the elements, but embracing them.