How to layer up?

When it comes to packing for a trip to the mountains its very important to align yourself with the terrain, weather, local conditions and pack accordingly.
There is a fine line of difference between packing what you “need” vs packing what you “want”. While the contents of “need” should suffice to help you stay comfortable and survive against the natural elements, the contents of “want”, well lets just say, will differ person to person and may also involve moving wardrobes altogether.
It took me a while to figure out how to truly differentiate between what I need vs what I want. Eventually over time, my backpack progressed from a bulky wardrobe to a minimalist pack with just the bare essentials.
One thing that really helped me finetune my decisions was to understand how I wanted to layer up for the excursion. A typical succession of layers is identified as under:
> Layer 0
> Layer 1
> Layer 2
> Layer 3

Layer 0
Also known as Base Layer as it sits directly on your skin. The #1 rule to choosing this layer is to check its moisture wicking property. The more it wicks away moisture, the better suited it is to sit on your skin.
You see, the skin is the largest organ in the human body and one of its most important functions is thermal regulation by sweat evaporation. If for any reason the body is not able to dissipate the heat produced internally, then it may go into a state of hyperthermic shock or overheating.
If a fabric is designed to wick away moisture i.e. it does not retain sweat or moisture as the fabric itself will push the moisture to the outer surface away from the body and dry quickly, then it is well suited to sit directly on your skin as layer 0.
Additionally this layer may also have thermal properties to provide warmth, as in the case of ski base layers.

Layer 1
The active layer or layer 1 sits over the base layer, but not always necessarily so. In warmer conditions just a single layer may suffice, in colder environments you may need to add this layer over a thermal inner base layer. Again as with the base layer, its important to keep in mind that this layer too has excellent moisture wicking properties. It may additionally have abrasion resistant patches (refer pic above) to counter the effect of backpack friction or it could also have thermal properties to provide some warmth. Having a full sleeves top with UV protection is also ideal wear for this layer.

Layer 2
The soft shell layer is your immediate line of defense against the elements, in particular wind and cold. The soft shell comes in various types; ultra light windbreakers, compact down jackets, padded jackets, or even the good old polyester fleece/wind jackets. The main objective for this layer is to protect you against wind chill effect (thermal loss due to wind exposure) and cold temperatures. Additionally, some manufacturers may also treat this layer with a water repellent solution which enables the shell to repel water (slight drizzle of light snow) under low intensity and small time durations. Keep in mind though, these layers are NOT waterproof, just slightly water repellent. They may keep you dry for a short interval, not a sustained duration. These shells will either have a combined wind and thermal protection or just individual protection. Personally, I prefer separate wind protection and thermal shells. A point to note, ultra light jackets and down jackets are super compressible and compact, thus take less space, while a typical fleece, polyester jacket or even the padded jacket will be a bit more bulky and voluminous. Compact and light is any day better over big and bulky.

Layer 3
The #1 rule when it comes to layering up in the mountains is to stay dry, if you are dry only then you can stay warm. This is where layer 3 or the Hard Shell comes in. The primary objective of this outermost layer is to keep you dry, thus it needs to be waterproof. Hardshells too come in varying types, from the ultralight to the ultra-bulky, all offering ample waterproof protection for sustained duration and higher intensities too. However what really sets them apart is their ability to breathe. In other words, their ability to let out sweat as vapour molecules without letting in any water molecules, thus helping you regulate your body temperature and staying dry at the same time. Fabrics such as Gore-Tex, DryVent, Pertex Shield etc all work on the lines of offering waterproofing along with breathability.

Summary
Now that you have understood the various type of layers, here’s a simple guide to get things into perspective and help you pack:
> Layer 0 & 1: The Base layer & Active layer. Primary objective to assist in moisture wicking (breathability). Can additionally have thermal insulation. You can plan for just one layer if conditions are warm and comfortable or 2 layers if heading for colder environs.
> Layer 2: The Soft Shell. Primary objective to provide protection against wind and/or cold temperatures. You can opt for 1 shell that provides both wind and cold protection or take 2 separate shells.
> Layer 3: The Hard Shell. Primary objective to provide waterproof protection. Additionally, the more breathable the fabric, the better.
> Thinner the layers, the better. In principle each layer acts as a thermal insulator by trapping thin veils of air in between. Its anytime better to have multiple thin layers which help trap more layers of air, rather than just one bulky layer which will have by default poorer insulation. Also, the thin layers are less heavy and more compact.
> Layering up for active vs resting state: Keep in mind, when active, you need to let your body breathe as much as possible as your core temperature is high. Hence having breathable layers is essential as it will help the body stay cool. When resting your core temperature drops, so providing your body with adequate wind and thermal protection becomes necessary. Hence having thermal layers is essential for this state.
> Fabrics that help with moisture wicking are:
– Polyester
– Polyamide
– Nylon
– Merino wool
> Cotton is a BIG NO for any layer, as it retains moisture and does not dry quickly.
> A good thing to have is stretch capacity with a minimum 2-way stretch if not a 4 way (left-right / up-down) in the fabric.
> Finally, always consider the local conditions, weather and the terrain you’re in and layer up accordingly. It is not necessary to always have a hard shell as your outermost layer or for that matter a soft shell too. If its raining but not cold, perhaps just a hard shell over a base layer will do. If it’s windy, cold and wet you may need to add on all layers.

Stay dry, warm and comfortably breathable.