Layering is essential for maintaining core warmth, comfort and preventing weather related problems. It also helps if you want to go light: you can carry less and still have the ability to dress correctly for whatever is outside.
Layering allows you to build a tiny microclimate that surrounds your body and can be adapted to moisture, wind, temperature, and exertion. In it very basic form layering is divided as follow:
- Base Layer: The inner-most layer. This layer is critical because it’s in direct contact with your skin.
- Mid-Layer: Provides insulation and continues the transportation of moisture from the inner layer.
- Outer Layer: Protects you from the elements and should allow air to circulate and excess moisture to escape.
These items must be synthetic since we want them to dry fast. Cotton and other natural fibers absorb water and take longer to dry. This may lead to hypothermia even when the temperature is not so cold.
This layer is critical because it’s in direct contact with your skin. Base layers (sometimes referred as underwear) should transport moisture away from the skin and disperse it to the air or outer layers where it can evaporate. Because water is such a good heat conductor, wet clothing draws body heat away from you.
The best base layer materials are synthetics (polypropylene and polyester). These are light and strong, absorb very little water, and are quick to dry.
Base layers are available in light, medium, and heavy weights. Light layers suit aerobic activity where sweat dispersal is paramount. Midweight underwear provides moisture control and insulation for stop-and-go activities. Heavy layers are best in very cold conditions, or when you’re relatively inactive.
Here you have from left to right, a light base layer, a mid-weight one and a heavy, winter base layer.
Socks play a huge role in the base layer. Choosing the right weight and fabric is critical for keeping your feet warm or cool during extended periods. In the picture you have heavy weight alpine socks with its liners (for moisture wicking), a mid weight pair and an ultra light running pair, just to give you an example.
The mid-layer provides insulation and continues the transportation of moisture from the inner layer and into the outer layer. To slow heat loss, this layer must be capable of retaining the warmth generated by your body. Wool and synthetics are well suited to this because the structure of the fibers creates small air spaces that trap molecules of warm air.
The layer’s thickness, as with the base layer, will vary by the temperature outside. A lighter mid layer is suited for a warmer day or a cold day with activities that are demanding (like climbing or nordic skiing); while a thicker layer works better on cold days with activities that are more static. Mid-layer items can become outer layers as well.
Light-weight mid-layers such as the Patagonia R1 collection are great for high output activities in moderate cold conditions or as an outer layer on cool days.
The heavier fleeces are great for colder temps or for activities where there are longer periods of inactivity, such as stop and go missions or while stalking.
The outer layer protects you from the elements and should allow air to circulate and excess moisture to escape. For dry conditions, a breathable wind proof shell or a soft shell may be all you need. If you expect conditions to be more severe, a waterproof hard-shell rain jacket might be the one needed. A shell made of a breathable and waterproof fabric, such as H2No or Gore-Tex, will protect you from wind and rain, and allow water vapor to escape.
A warning note: Waterproof breathable is just an idea, there is not such things as waterproof breathable. Any hard shell that can keep the rain out will have a hard time letting your body heat and vapors out as well. If you are using a hard shell for a static activity this might work well, however is most active endeavors you will find yourself dump inside from the sweat build-up.
A especial kind of outer layer are the insulated garments. Like their name state, these items have a form of natural or synthetic insulation, usually within a soft shell or a waterproof breathable fabric. These are great items to throw on top of all your clothing when you stop and it’s really cold outside, it helps maintain the heat your body created while you were moving.
Let’s start with pants. Like on previous layers, the outer layers can have different thickness.
Soft shell jackets are the right answer to take outside for most conditions. Except for when it’s really poring, a good soft shell jacket will protect you from the wind, snow, ice and mild rain. Again, choose the thickness according to the weather.
The system works best when combined:
Wear a lighter mid-layer (like Patagonia’s R1) for when you are moving. Wear a soft shell on top for wind and light rain / snow protection. When you stop throw on top an insulated jacket to maintain that body heat and prevent it from escaping.
The system I usually wear when climbing or while patrolling on mountain terrain:
- A Capilene 1 long sleeve tshirt as a base layer (or Capilene 2 for winter). I might carry an extra one on the pack.
- An R1 Pullover as a mid-layer (or a slightly heavier fleece in winter).
- A softshell jacket that breathes very well and keeps light rain and snow out. If I know I will be needing more rain protection then I’ll bring a hard shell jacket too (stashed on the ruck).
- For the legs I use either nothing at all, a Capilene 1 bottoms for spring/fall or a Capilene 3 for winter, together with a pair of soft shell pants.
- On my pack I would bring an insulated jacket.
This system is light, breathes very well and it can be adapted to pretty much every occasion, even when armor needs to be wore on top. This system also keeps you warm or cool and it dries very quickly.
Stay safe, stay dry and stay warm!