Merino wool has no equals when it comes to building next-to-skin and layering pieces for mountain hunting.
Historically, the term “merino” specifically referred to the wool from Merino sheep reared in Spain. However, due to the equivalent quality of Australian and New Zealand wool it now has a much broader meaning. Merino sheep have the finest and softest wool of any sheep. Merino’s wool is finely crimped with soft staples 2.5-4 inches long and less than 24 microns in diameter.
Since forever, wool has been a natural, renewable, sustainable, wicking, breathable, anti-microbial, odor resistant, flame retardant and biodegradable fiber that, much like human hair, is made of keratin. Keratin is a tough, insoluble protein with a unique structure providing it with a natural resistance to sunlight, water, acids, rot and mildew. For these reasons, as well as many more, wool has, traditionally and historically speaking, been a technical and performance fabric. But until recently, until the refinement and availability of merino, wool has been uncomfortable to wear next to your skin.
Today’s merino wool is not the same itchy rough wool our fathers wore. It is soft and comfortable, and provides many technical advantages over old-school wool as well as modern synthetics.
Merino is excellent at regulating body temperature, especially when worn against the skin. It provides some warmth, without overheating the wearer. The fabric draws sweat away from the skin and is slightly moisture repellent (keratin fibers are hydrophobic at one end and hydrophilic at the other), allowing the wearer to avoid the feeling of wetness.
Merino can absorb moisture up to 1/3 its weight. Unlike cotton, it retains warmth when wet because it pulls the moisture away from your skin.
Merino is naturally anti-bacterial resistant, which causes the fabric to resist odor caused by sweating. This is a huge advantage compared to synthetic fabrics and ideal for extended backcountry hunts.
Merino is incredibly soft, due to finer fibers and smaller scales which eliminates the itch associated with regular wool.
Merino has an excellent warmth-to-weight ratio compared to synthetics and to other wools, in part because the smaller fibers have microscopic cortexes of dead air, trapping body heat similar to the way a sleeping bag warms its occupant.
The breathability, or the ability to dissipate perspiration, of Merino fabrics brings about temperature changes where two things can happen: 1) When there is a rise in humidity in the microclimate between the skin and the merino fabric, moisture vapor is absorbed then transported and released into the air outside of the fabric, keeping you dry, reducing clamminess, and creating a noticeable drop in temperature for the wearer. 2) Conversely, if the ambient temperature should drop, moisture from the air can be absorbed by Merino and converted to bound liquid, a process that produces a rise in temperature known as ‘heat of sorption’.
The active ability of Merino to react to changes in one’s body temperature and the microclimate above the skin is further enhanced by Merino’s insulation capacity. Merino has the ability to insulate the wearer from extremes of cold, and also help protect the individual from excessive heat. The thermal insulation provided by a Merino fabric is due to the air trapped between the fibers, and as Merino is much finer than most other textiles, it contains more air spaces, and provides greater insulation.
Merino is naturally odor reducing due to its physical and chemical structure. The ability of Merino to absorb and transport moisture (sweat) away from the skin where it evaporates into the air, prevents bacteria developing and creating unpleasant body odors. Sweat itself has no odor, but if it is allowed to remain on the skin, bacteria will develop and so will body odors. Merino fibers are scaly on their surface with no charge, providing an anti-microbial environment. This means that the bacteria are not attracted to or able to penetrate the scales, like they are the smooth, positively charged surface of a synthetic fiber.
The non-reflective surface of Merino fabrics provides enhanced visual concealment. Adding to this concealment, Merino is a silent fabric, with no rustle or swish sounds as you move. Merino reduces the effects of the sun’s rays protecting you from up to UPF 50 & 40 when wet.
Merino wool is also naturally flame retardant.
Merino fibers are strong and long, enabling a durable fabric that is less likely to pill, and has excellent drape and wrinkle recovery. As Merino fibers are natural, and are made up of keratin proteins, they are very resilient - A Merino fiber can be bent 20,000 times without breaking. When a Merino fiber is wet, it can be extended up to 30% without damage. When the extension is released, the fiber then recovers completely to its original dimensions.
Together with the breathability, moisture control and thermoregulation that Merino provides, the fine micron of Merino ensures it feels soft and comfortable next to the skin. Unlike coarser micron wools, fine Merino fibers bend with pressure against the skin, flexing so as not to agitate the nerves. The natural elasticity of Merino fibers means they stretch with the wearer, and then return to their natural shape so there is less chance of the garments losing their shape.
The key to Merino is simple, it’s about understanding microns and intended usage.
Wool is expressed in microns, the unit of measurement used for the fiber’s diameter. One micron equals one millionth of a meter. The lower the micron of a fiber, the finer it is, and the finer the wool the softer it is next-to-skin. Wool fibers vary in diameter from 11 - 60 microns. Merino fibers are the finest of all wool types and are usually less than 24 micron. An overview of micron ranges: strong (broad) wool 23 – 24.5 micron, medium wool 19.6 – 22.9 micron, fine 18.6 – 19.5 micron, superfine 15 – 18.5 micron and ultra fine 11.5 – 15 microns.
We’ve all heard complaints about wool being itchy and uncomfortable. Here’s why. Traditional wool has larger fibers and scales, which could be felt and would cause you to itch. That’s why for next-to-skin or baselayer, we recommend a soft and comfortable Superfine Merino. While most of the baselayer market is dominated by 18.5 micron Merino, our testing and research suggests 17.5 micron Merino is well worth the additional cost.