Keeping warm in cold rugged conditions have been humans struggle since the dawn of man. Our body doesn’t have fur (anymore) and we have few tools to regulate body heat compared to other animals living in sub-zero conditions.
As if this wasn’t hard enough our body generates heat when we are active. Heat equals moist, and moist equals cooling, or in worst case hypothermia.
Thank god humans are capable of inventing things.
What is layering?
The basic principle of proper layering looks as such:
Functionally the keys are to stay as dry as possible close to your skin. This is done by dressing in a moist transporting layer closest to your body, while the outer layer at the same time keep moist and wind out. The middle layer is mainly for warmth but should have some breathability as well as not to keep all the moist stuck between the layers.
A big trend these days is to use a 100% merino wool base layer. Merino wool can keep the warmth while moist, something cotton and other materials fails to do. It also smells less so you don’t have to wash it as often. But it’s not a necessity. As long as you have base layers that can transport moist, and have the capacity to dry up somewhat fast. Besides merino wool, the most common base layers are made out of synthetic fibers. The moisture transportation is called wicking
The base layer should fit snugly in order to work optimally.
Mid-layers can vary heavily in shape and form. Some use down, some use fleece, some use Primaloft, and som a fusion of the mentioned above. This depends on the purpose of usage. If you are a keen ski tourer, you will get really sweaty and therefore it can be a good thing to have a mid-layer which is transporting moist as well as the base layer. If you’re just skiing, you’re less likely to be really sweaty. For those people down is a good option. If you get the down wet from sweat it breaks down, and won’t provide you warmth. This layer can also be referred to as the “insulation layer.” But if you ask me I would call that splitting hair.
The fusions can be a down jacket with Primaloft arms or an artificial down which won’t break down due to wetness.
Another aspect of this is a warmth to weight ratio. Since you don"t want to put on extra weight to make, hiking, skiing, or climbing tougher on you. Thankfully these products are often very lightweight.
Shell Layers / Outer Layers
The three-layer jackets or pants that should be used as an outer layer are often shortened 3L jackets or GTX as a shortening for Gore-Tex. There are 2,5L and 2L as well, but let’s focus on 3L.
These are built up by:
Outer layer (face fabric) - usually made of nylon or polyester.
A membrane - a waterproof layer and is most commonly made of expanded Polytetrafluoroethylene (ePTFE) or Polyurethane (PU).
An inside - a very lightweight backing fabric is attached to the interior.
All glued together so it will seem like only one layer. These are robust, durable gear that should resist storms, rain, and heavy snow without letting any in.
The functionality is measured in pillars. Water pillars and steam pillars. These let you know how much waterproofness and how much breathability a garmon has. These are hard to combine, so often it’s leaning towards one or the other.
The density of Gore-Tex for example is described as 40D or 70D. These tell how many fibers per square centimeter the fabric contains. Higher number = higher density = more robust fabric.
The high tech membranes used by all manufacturers work pretty much the same way - and are actually not that high tech, as one might think.
Moist molecules are smaller than water molecules. The functional membranes are just a layer with holes big enough to let moist molecules leave, but keep the water molecules out. A quite basic function right? In other words - a waterproof yet breathable fabric.A Gore-Tex® membrane thru a microscope
Even though not as high tech as one might have thought, the material is also used as artificial blood vessels and guitar strings. The most well known technical membranes are.Gore-Tex®Dermizax FuturelighteVent™Entrant®Polartec®Sympatex™
Why is layering superior?
Humans have used this principle forever. Different treatments on different leather types, used differently, gave materials different functionality. Suited for different climates. Layering is superior because it’s custom made for skiing or other outdoor activities. The main function, besides keeping you warm, is to transport sweat and moisture, created on your skin, to the outside of your jacket or pants.
Another positive is that it is interchangeable. Feeling cold? Add another layer. Feeling warm/getting wet? Lose a layer/open a vent. The big part about layering is unprecedented for keeping dry and staying warm.
How does layering work?
Layering basically means dressing in layers, where all layers have different functions. Together they build total protection.
Why is layering such a big deal?
As with most gear, it’s developed for the most dedicated riders. Layering will be put to most use if you ski A LOT, and very intense. Maybe adding a dose of hiking also. If you are a recreational skier, who skies a few weeks a year, and are in it for the good times and beers at the end of the day. You probably don’t need a high technical ski clothes setup. You won’t be as sweaty and if you get wet you will have a cup of coffee and your pants or jacket will dry up enough for you not to get hypothermia. With this said, anyone can benefit from dressing in the proper layers. Staying dry is comfortable, staying warm is comfortable, skiing is fun. Layering lets you worry less about bad weather and care more about skiing.