The multi layer principle
Guide: Our complete multi-layer system
Guide: Our complete multi-layer system
For any extended outdoor trip, appropriate clothing is essential. In variable weather conditions, or if you intend to engage in activities with varying degrees of exertion, it’s important that the garments you wear are well matched to each other and allow for plenty of variation.
By dressing in several thin layers, you can put together a combination of clothes that you then adapt to the current weather conditions and that properly ventilate the body's excess heat according to the activity you are performing. This concept, we call the Multilayer Principle, or the layer-on-layer principle.
The Multilayer Principle is a model which describes the different layers we use in a system of clothing. It describes the different properties each different layer has and the function they perform.
The four layers
Applying the Multilayer Principle does not mean that you should always wear every layer, but rather it encourages you to change your clothing according to environmental factors such as temperature, wind and the degree of physical exertion. The multilayer principle also includes using each garment's specific features, such as hoods, pockets and ventilation, so that the different layers are actively supporting each other.
Layer 1: The base layer
The base layer is the underwear that is worn closest to the body, whose main job is to transport moisture away from the skin to keep it warm and dry. In autumn and winter, we recommend wool underwear. Wool has superior properties when it comes to dealing with external temperature changes and the body's own excess heat that turns into moisture during physical exertion.
Layer 2: The mid layer
The mid layer is often made up of lighter jackets, sweaters, thermal trousers and slightly heavier underwear that insulate layers of air. It also absorbs/transports moisture away from the body through the exchange of air between the different layers as we move. Here you’ll also want some ability to open and close zippers as well as use a hood and drawstring shoes to regulate body heat.
Thinner thermal jackets, fleece sweaters and shirts work well as mid layers. Garphyttan's middle layers are made of polyester or cotton. Polyester is a synthetic material that does not bind any moisture inside the fibre, giving it good moisture transporting properties. Cotton, on the other hand, absorbs a lot of moisture and therefore works well with a base layer of wool. It’s important to change a cotton garment regularly as they cool down when they get damp.
Layer 3: The outer layer
The main purpose of the outer layer is to protect the underlying layers. Here you’ll want garments that are versatile and durable. They should also be roomy and allow plenty of room to move.
It's an advantage to be able to open and close your zippers, as well as use hoods and drawstrings to regulate body heat. Trouser and jacket pockets also play an important role in the multilayer principle. They should be able to hold, for example, some of your reinforcements or even one or two small bottles of water. Pockets filled with warm bottles of water act as heating elements and help keep your body warm when doing low-intensity activities in cold environments.
Jackets, anoraks and trousers in a cotton/polyester combination have long been one of the most cost-effective and functional solutions for a sturdy and durable outer layer. Cotton/polyester also has the advantage that it can easily be impregnated with beeswax, which makes it more durable and water-repellent. Read more about how to wax your outdoor clothes here!
Layer 4: The reinforcement layer
Reinforcement layers are usually divided into two categories: those specifically designed to protect against strong winds and more persistent moisture and those designed to provide thermal insulation. These layers are therefore used more for specific occasions when you want to feel comfortable during breaks, overnight stays or if you find yourself in an emergency.
You can also wear extra socks, a hat, scarf, sweater, jacket and trousers as extra reinforcement layers. Many of these items are part of the middle layer but can be classified as reinforcement layers as well. When thinking in terms of the Multilayer Principle, you should also consider your sleeping bag and shelter, such as a tent or hammock, as important reinforcement layers.
The fit - things to consider
Having air space between your layers increases your clothes' ability to keep you warm. As air conducts heat poorly, heat stays in and between the layers. So don't dress too tightly.
However, some air exchange is important, as stagnant air can easily become damp, especially when you are physically active. Exactly how long the heat is retained depends on the properties and combinations of the materials and your ability to use the different layers of clothing. If you choose clothing, gloves or shoes that are too tight, it limits the space for the insulating air. Also, don't choose clothing that are too big, as this can instead make it difficult to warm the air, and they can easily become uncomfortable to wear.
Change your clothes in case you get wet
In many situations, the ambient temperature can alternate between hot and cold, such as when you move from an indoor environment to an outdoor environment. In addition, your physical activity may also vary in intensity. In these cases, you risk getting damp as well as wet, both inside and outside. Wet or damp clothing loses its thermal insulating properties to varying degrees depending on the material it’s made of.
Regardless, the risk of hypothermia increases. It is therefore important to change into dry clothes. The most important thing is to change your underwear (the base layer) to keep your body dry. Always make sure you have a spare pair of underwear that’s always kept dry in a waterproof bag so that you sleep well at night and have a good backup in case of emergency.