Lightweight hiking: the three-layer system for dressing with the minimum

When you try to lighten your pack, clothing is often the first place where you carry too much. The guide François Jourjon published on Randonner Malin about the three-layer system struck me as a good foundation: use the fewest clothes for the most effect, and stay at a comfortable temperature both while moving and while stopped.

The first layer, against the skin, should wick sweat away and dry quickly. The author advises against cotton, which absorbs moisture and cools you down, and compares quick-drying synthetic fibers with merino, which is warmer but more fragile. The second layer insulates by trapping air: fleece or synthetic insulated jackets, which still protect when damp, or down, which insulates much better for its weight but handles moisture poorly. The third layer blocks wind and rain while letting sweat escape, because there is no point avoiding the rain only to end up soaked in sweat.

What I found most useful for a light pack is that you do not always need all three layers. In strong wind without much cold, you can combine a merino t-shirt with a breathable rain jacket. In dry, very cold weather, a base layer plus a mid layer or two is enough. Some garments serve several roles, such as softshells or windproof fleeces, which lets you reduce the number of pieces.

The last piece of advice is not to overdress while moving: you sweat, then get cold when you stop. It is better to take a layer off before you start sweating and use ventilation, such as underarm zips. A simple article, but one that stops you from carrying a ton of clothes.

Source: Randonner Malin