How to Choose Base Layers & Mid-layers






A basic layering system has three important functions: to wick sweat away from the skin; to trap body heat; and to protect you from the weather. Each part of your clothing serves a different purpose, and works with the other layers to keep your skin dry, warm and comfortable. An effective layering system allows you adjust and regulate your body temperature when active or resting or as weather conditions change. Knowing how to choose your layers could make all the difference.

Layering system diagram



Base Layering Guide

What is a base layer and what does it do?

Icebreaker Merino Base Layer

Finding the right base layer can be confusing. With different brands to choose from, different fabrics and different styles why should you choose one base layer over another?

A base layer is the 'next to skin' foundation on which a layering system can be built.

Your base layer's main function is to wick sweat away from your skin and towards the outer fabrics, helping you to regulate your body temperature. Moisture conducts heat 25 times faster than air, so if it can't escape the surface of your skin, you become cold very quickly. In summer, a base layer worn under another light layer will help to reduce your skin's surface temperature through a process called evaporative cooling. They should be close-fitting for for them to work effectively. Don't be fooled into thinking your cotton t-shirt can do the job of a base layer as cotton will hold moisture and you will become cold very quickly.

What are base layers made from?

Base layers are made from synthetic polyester or fine Merino wool as they are both very good at wicking moisture. Cotton t-shirts should not be used as a base layer for active use as cotton soaks up moisture and holds on to it, meaning you become damp, clammy and ultimately cold.

You should choose your base layer based on what kind of activity you'll be doing, as well as the duration and location of the activity. For example, hiking in warmer climates will require a lightweight base layer (for wicking moisture only) whilst skiing in Whistler in January will require a heavier weight base layer to boost warmth.

Synthetic Polyester Base Layers vs. Merino Base Layers - Which is better?

It's important to consider the benefits of each of the different fabrics to ensure you find the one that's perfect for you.

Polyester Base Layers

Merino Wool Base Layers

  • Quicker drying time.
  • Lightweight
  • Costs less (when compared with Merino Wool)
  • Durable
  • Easy to care for
  • Doesn't itch
  • Outstanding warmth
  • Odourless after many days of wear
  • Wrinkle resistant
  • Exceptionally comfortable to wear
  • Machine washable (read about how to care for merino wool here.

Synthetic base layers are available from The North Face, Arc'teryx & Skins.

Merino Wool base layers are available from Icebreaker & Mons Royale

Click here for our full collection of base layers and thermals.

Base Layer Button



What is a mid layer and what does it do?

A mid-layer is any piece of clothing worn over your base layer and/or under your outer shell. Mid-layer choices can vary greatly, from microfleece hoodies to down vests depending on conditions and activities, but they all serve to keep you warm.

The mid layer's role is to insulate and trap body heat, while continuing to allow moisture to make its way to the outer layers. The kind of mid layer you choose may vary according to the conditions you're in and the activity you're participating in.

What are mid-layers made from?

As their function is to provide the insulation of your layering system, a mid layer is dependent on 'loft' - space in which to trap warm air. Materials with this property include Microfleece, Merino Wool, Synthetic insulation and natural down. Each of these have their own benefits and are suitable for certain conditions.

  • Microfleece

    Microfleece is highly versatile and available in a wide range of thicknesses. Thinner Microfleece garments are very practical, quick drying and make a great option for high-output activities in the cold such as cross-country skiing. Mid to heavy weight fleece jackets are more suited for cold situations in which you'll be still or inactive, such as setting up camp, but they can weigh more than other forms of insulation and aren't as compressible.

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  • Merino Wool

    Merino wool is an excellent natural insulator, and thicker merino fabrics make ideal mid-layer options for activities such as skiing and winter walking. Icebreaker's MerinoLoft technology blends merino and synthetic technology to increase its loft and heat-trapping capabilities while continuing to keep you warm even when it gets wet.

    shop merino mid layers
  • Synthetic Insulation

    Synthetic insulation is a versatile and practical option for a lot of people. Strands of synthetic fibre create a down-like material that traps heat effectively. It continues to work when wet, dries quickly and is easy to care for.

    Shop synthetic insulated tops
  • Goose or Duck Down

    Weight for weight, down is the best insulator available, but with the exception of hydrophobic down, it must be kept dry for it be effective. This means it is best saved for very cold but dry days. As it is such an effective insulator, it makes an ideal layer for low-output activities such as belaying or camping.

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For more information, read our in-depth Insulated Clothing Buying Guide



waterproof shells

What is an outer shell?

Your outermost layer, also known as the 'shell' is the main defensive barrier against the wind and rain - usually a waterproof jacket. By preventing further moisture getting into your clothing, it allows the base and mid layers to continue to wick moisture away from the skin. For a layering system to work well, a shell must be both waterproof and breathable, stopping rain entering, but allowing sweat vapour to escape.

What are outer shells made from?

Hard shells are made from laminated membranes: a stiff outer face fabric for durability; a waterproof, breathable membrane such as GORE-TEX in the middle; and an inner membrane to protect this from contaminants such as skin oils and dirt.

For more detail about hard shell fabrics, read our full Waterproof Fabrics Buying Guide.

Soft Shells

The term 'soft shell' covers a huge variety of fabrics and technologies, but they all share an emphasis on breathability and manoeuvrability rather than total waterproof protection. Unlike hard shells, soft shells offer stretch They are designed to provide a only degree of rain resistance, and usually have a Durable Water Repellent (DWR) coating to the face fabric, but in heavier rain a hard shell is recommended.

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