Ever been deluged with messages about Merino wool? I have been. My friends, neighbors, professional associates, and a slew of advertisements all toll the virtues of Merino wool and its abilities.
The term “wool” is technically fabric from sheep, goats, llamas, alpacas, yaks, and similar animals. When we talk about Merino wool, we speak of wool from Merino sheep. Merino wool is often preferred to other sheep wool.
So, if it’s this good, I thought, why do we still use other materials for our outdoor wear? Why aren’t all of us snowshoers wearing it for all three layers?
I got curious enough to investigate outdoor-fabric products, customer experiences of these products, and the science of staying warm while active outdoors in the winter. Here’s what I found.
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The Truth to Layering
Before we jump into the Merino wool’s impact on keeping us warm, there are a few layering aspects to clarify.
First, the three layers we hear about – base, insulating, and shell – are based on sound science.
We need a base layer to move sweat away from our skin. We need an insulating layer to trap heat in the air space around our body and keep our sweat moving out. And we need a shell layer to protect our body from the snow, wind, and cold air and allow our sweat to evaporate.
Second, clothing can make a big difference in all three layers, whether we get lightweight, midweight, or heavyweight (expedition weight).
Lightweight is for high-energy activity on a mild day. Midweight is for moderate-energy activity on a moderately cold day. And heavyweight – or expedition weight – is for a frigid day in the mountains when it’s below zero.
Read More: Thinshell Layering
Merino Wool as a Base Layer
Based on the truths of layering, it is tough to refute that Merino wool is an ideal base layer for snowshoeing.
Wicking and Drying
Our base layer – the clothing next to our skin – is about sweat management. Sweating cools our skin, our circulatory system, and our body. Sweat sucks heat away from our body 25 times faster than the air, and wet skin cools 25 times faster than dry skin. When our skin is humid, our body senses heat, and we sweat even more. So to keep our skin dry, we need a base layer that wicks – that draws sweat away from our body, spreading it through the fabric.
Compared to other fabrics in this study, wool and wool blends were quick drying and had some of the fastest drying rates after 5 minutes of becoming wet. This finding was even more so when these fibers were drying at a high temperature. In moist conditions, however, wool can dry more slowly than other synthetic fibers.
Also, thinner fibers that are part of a larger fabric can have increased wicking properties (in a study of natural cotton fibers). For example, Merino wool, which is finer and lighter than traditional wool, is said to have better wicking and drying properties than other types of wool.
Merino wool is soft, stretchy, supple, and comfy. Compared to other wools, Merino wool is often tolerated better by the skin (like in this study with children who have chronic inflammatory skin disease). In addition, Merino wool can typically be machine washable, unlike other types of wool.
Other synthetic materials, like polypro, can be scratchy; you don’t want it next to your skin. However, as synthetics evolve, include scent eliminators that you might allow next to your skin. For example, X-Static technology (now Ionic+) uses positively charged ions to eliminate microbes and, thus, odor. Acrylic long johns, Cupro fabric, and the synthetic down Polyguard can provide three other alternatives.
Other Natural Properties
In addition to its moisture properties, wool is flame-retardant. So we can sit by our fireplace or campfire in our wool-long johns without worrying whether a spark will set them ablaze. Merino wool is also elastic and retains shape; you can bend a wool fiber 20,000 times without breaking it.
Wool, including Merino wool, has anti-bacterial and antimicrobial properties compared to other fabrics. For example, in a comparison against other materials, polyester had more foul-smelling odors after exercise. From experience, polyester seems to stink no matter how often you wash it.
One of the downsides of wool and Merino wool is that it typically costs a bit more than synthetics.
Here are a few examples of companies producing Merino wool or wool blend base layers for snowshoeing.
Merino Wool for a Mid-Layer
Merino wool is as good for our insulating layer as any other material on the market.
The slower our heat energy transfers away from the body, the warmer we stay. Like a sleeping bag, our insulating layer traps our body heat as it traps in the air around our body. As a result, our body protects us from cold with its heat as long as we keep it near us. Our insulating layer locks in place the air that our body heats while keeping our sweat moving away from our body.
The best insulating layers are vests and sweaters made of fleece, polyester blends (including pile), acrylic and other polymers, wool, and cashmere. For most of us, the choice comes down to wool or fleece.
Polyester fleeces are light, more affordable than wool, and are water-repellant, but they degrade in harsher environments (and can be torn up by thorns). In addition, fleece is flammable; it is risky to wear it near a fireplace or campfire. Again, they may also be noisy and stinky, although antimicrobial treatment can help maintain the garment’s freshness.
One of the benefits of wool as a mid-layer is it retains 60 percent of its insulating qualities when wet. This quality makes it a better insulator when wet than polyester. Thus, Merino wool does keep us warm as a mid-layer. Also, wool is more wind-resistant and more durable. However, wool’s downside is, as mentioned before, that it costs more.
Many companies with good reputations offer mid-layer Merino wool attire that can insulate us while snowshoeing. Among the unique mid-layer wool attire are the following:
Merino Wool for an Outer Layer
Merino wool is not typically used as an outer layer for snowshoeing
Instead, try a hard-shell jacket that is water-repellant (preferably water-proof), wind-resistant, and largely wind-proof, with some “breathability.” A robust and durable shell – a non-insulated jacket – is ideal and will keep snow, cold air, and wind out of our base and insulating layers.
Even Merino wool, when not coupled with a finish to protect us from the elements, doesn’t measure up to the alternatives for our outer layer.
Read More: Jacket Reviews
For ten thousand years, human beings have met the challenges of winter with clothing made from sheep’s wool and through the use of snowshoes. And since the late 1990s, winter outdoor sports have been in the throes of what some observers call a Merino wool renaissance.
Today, we can build on all this experience with snowshoeing and wool to keep ourselves warmer than ever on our snowshoeing experiences.
Do you use Merino wool in any of your snowshoeing gear? What are some of your favorite Merino wool layers? Please share your insights with us in the comments below.
This article was first published on November 10, 2014, and was most recently updated on December 22, 2022.