The multi-layer principle is a flexible method for dressing for the outdoors. Three to four layers provide protection from the cold, wind and rain, and are easy to adjust as your body temperature changes. You are the one who decides, after all it is your sense of well-being that determines what kind of clothes you wear. A fleece sweater, which in reality is a middle layer, may be the perfect outer layer on days with mild winds and comfortable temperatures, and as spring unfolds you might only need to wear a base layer. In other words, the multi-layer principle is a theoretical model for how to dress functionally, but it is not a hard and fast rule.
Potential multi-layer solutions in different situations
• High intensity activities: base layer + uninsulated outer layer
• Mid-intensity activities: base layer + insulated outer layer
• Low intensity activities: base layer + middle layer + outer layer
• Breaks, resting and emergency situations: the same as low intensity but reinforced with a middle and/or outer layer
Be proactive and adjust your clothing regularly based on the weather, wind and activity! If you wait – because you are tired, lazy, not in the mood or do not want to bother your companions – the group can have problems later.
Remember to help your garments breathe! Open the neck, cuffs or ventilation openings when you are active and warm. This will allow you to release excess heat, which in turn decreases the risk that the inner layers will get wet and lower your body temperature.
First ventilate – then reinforce
When you stop to take a break, it is often a good idea to release excess body moisture before you put on your reinforcement garments. In reality, this might be unnecessary to point out since we often, by instinct, unzip our jackets and maybe pull off our hats and gloves and rest for a moment before we put on our thick down jackets. Whenever you have a chance, for example when sitting in your wind sack or lee side, you should take off your shoes and socks for a moment, and preferably even change your socks. This will make a big difference when you are on long treks.