Your core is technically everything minus your legs and arms, but since we already covered the head, I won’t put you through that again. We have not covered the arms and legs, so for the sole purpose of this write-up we will consider this as part of the core layering system as well.
Leave it at home; it has no place in the backcountry, especially in winter. When cotton gets wet, it stays wet, then you get cold and then you get into trouble. I know, I know, cotton is so comfortable and soft, sorry, but that doesn’t help when looking at the larger picture.
There are two types of base-layers to consider; merino wool and synthetic. A base-layer is the next-to-skin layer that you will feel and have to live with all day long; be sure you find something comfortable. To fit a base-layer is not too difficult. It needs to fit, simple as that. Want a looser fit; buy a brand that supports a looser fit, or size up one? Want skin tight, they make those too?
You can purchase base-layers in all sizes and in 5-different weights: silk, light, mid, heavy, and expedition.
Merino wool base-layers: This is your most pricey option. These base-layers are soft and super comfortable to wear all day and even for multiple days. Wool has natural lanolin that fights bacteria, which in turn stops the piece from smelling like sweat and dirty cotton socks.
Merino wool is not the traditional wool that is itchy to even look at. It’s not your granddads wool; it’s much more comfortable, lighter and fits better. This is still wool though, so if you have an allergy to wool, you may still be allergic to these.
Synthetic base-layers: This is your most affordable option. These are similar to merino wool, in comfort and fit but are made of a different material. Rather than wool they are a manmade material, some of which is derived from petroleum based products. Synthetic materials do not have a bacteria fighting ingredient unless built into the fabric, which in my opinion, doesn’t work as well. Synthetic fabric tends to hold odors and overtime is hard to ignore, even for the wearer.
Farmer Johns and Janes: These are simply a one piece base-layer, no gap between the top and bottom layer here. Has a drop bottom as well for those times where you just have to go.
The mid-layer is just that. It can be of many different materials like fleece, wool, down or Primaloft, not cotton!!! The mid-layer often becomes your outer-layer when the temperatures are too warm or you need to cool off during high activity levels. It should not be a waterproof layer, leave that for the outer layer.
Most people don’t wear a mid-layer on their bottoms, but when they do, a high percentage of the time, its fleece. Your legs produce a lot of heat and don’t need the layering that your upper body needs.
Fleece: This is most affordable option of the four listed here. Everyone makes a fleece jacket, but some are better than others, but all will do the trick under most circumstances. Look for a tighter knit, the tighter the knit the better the fleece. The higher the number on the fleece the warmer it is; 200, 300, 400. Fleece is nice because it typically stays rather warm when wet and even when covered in snow.
Fleece is a manmade material; many companies use old water bottles to make the fleece fabric. The fabric is generally very durable and can take a beating.
Wool: Just like the base-layer, merino wool is the most comfortable. Wool stays warm when wet but tends to be a bit heavier than fleece. For the mid-layer you could use regular wool as it is not against your skin.
Down: Not used so much for a mid-layer because it can be too bulky. However, some companies are making a less bulky mid layer with a down fill. The problem with down is if it gets wet it loses all its warmth. I recommend down as a warmth layer, which you will read about in a bit.
Primaloft: This is a very popular mid-layer as it is light, not to bulky and somewhat affordable. Primaloft is a manmade down, so to speak. It was developed for the military and has hit the market hard in outerwear and gear. This material, unlike down, stays warm and retains its value and loft when wet.
Vest: These are nice to keep the warmth on your core and not any extra on your arms. These can also be found in all four materials.
The outer-layer should be your waterproof/breathable layer. Many companies are coming out with their own waterproof/breathable materials. The key as to how it works is not all that simple but somewhat easy to explain. The water particle is larger than the moisture particles so air can get out but water can’t get in. However, once moisture turns to liquid, it won’t get out either. This is mainly due to the fact that you will, in many instances, produce moisture faster than the material can disperse it. This is also a good reason not to wear the outer-layer unless needed to stay dry, to cut heavy winds or during lower activity levels.
Shell (uninsulated): This is the best option and is preferred for a layering system. This has no insulating value but does trap heat to a point and in turn make you feel warmer.
Shell (insulated): An insulated shell is too warm for a layering system unless it is lightly insulated and by that I mean a very thin liner. If the outer-layer is over insulated you have no need for a mid-layer. Then without a mid-layer you can’t de-layer appropriately.
A warmth layer is essentially a 4th layer that goes over everything. This is, 9/10 times, a down layer or what is called a belay jacket. This warmth layer even goes over your waterproof/breathable layer. The warmth layer usually stays in the pack and comes out during times of low activity level, around camp, above tree line, in windy, cold conditions or while lounging on a summit.
A 3-layer system is not 3-layers in one but a jacket with three options. The liner zips out making for a light jacket. The outer shell without the liner can be worn as a standalone as well, like a rain jacket or moisture barrier. The two pieces can also be worn together for lower activity levels, around camp or even around town.
These are a one piece jacket. These are not great for high activity levels. With only one layer you have to essentially peel away what would normally be a mid and outer-layer to not over heat, leaving you with only a base-layer on, which might not be enough. These jackets are too warm for use with a base-layer and a mid-layer. Leave the insulated jackets for lift serve skiing or for around town.
Like foot and hand warmers these guys help warm a certain section of the body. These are slightly larger and work best where blood vessels are closer to the skin. They should not be placed directly on the skin. Use in an area that you feel needs added warmth like the lower back or stomach.
For care or your winter gear and apparel such as; cleaning and storing, watch for my next blog on winter gear care. Check out my other blogs on Hand, Foot and Head Protection as well as Layering Materials. Still have questions about protecting your core or layering? Contact me here or stop into a local gear shop for answers to your questions and to see what gear and outerwear is available to you. Wish to have an introduction to winter mountaineering, snowshoeing or skiing, find me at a local guide service and we can set it up.