Does the Merino wool hype have any basis?

In the last 10 years or so, you won’t have been able to avoid Merino wool if you have had the slightly interest in the outdoors – it is just everywhere. It seems that every company out there is making at least one Merino wool product, even if they make only hardware! In any case, I have had a chance to see, try and regularly use many of the Merino brands out there, and I know that not all that shines is gold. Too many times Merino wool products are sold as performance clothing and accessories, even if they are not the right product, just because they are Merino.

I have gotten a little tired of this and decided to share with you my little rant, but this rant has some backing and real data, so you might even get something here. But, first what is it?

Merino vs Regular wool

Wool has degrees of quality and that quality is measured in microns (micrometer), which is the thickness of the actual fibre. In general, the thinner the fiber (low micron), the higher the quality is.

Wool has several characteristics that make it a unique and useful fibre for outdoor clothing:

1. Wool is naturally antibacterial – Merino wool, like all wools, have lanolin in them. Lanolin is a wax produced by the sheep’s glands meant to protect the wool and the skin from rain. Another benefit that Lanolin offers is preventing bacteria (which causes bad smell in clothes) from forming, making Merino a fabric that doesn’t need washing and will still stay fresh and non offensive (mainly to others) even after days, or weeks, of constant use.
2. Natural insulation – Merino wool is a “hollow-fibre”, which means that in the fibre there is trapped air that offers insulation even in the finest of Merino fabrics. This constant insulation means that even the thinnest Merino garments will have some level of protection for the wearer. The insulation is useful both for cold climates and for hot climates, increasing the wearer’s comfort.
3. Retains insulating properties when wet – Probably the most important factor if choosing Merino wool – the fact that it retains the insulation property means that even when you sweat, or got fully soaked, you won’t freeze (which can lead to hypothermia). This is the main reason why Merino wool underwear and baselayers have become so popular, especially with snow sports, in the last few years.

On the other hand, wool has one big issue against it – it is hydrophilic, meaning it absorbs liquid and retains it, taking a long time to dry out. Due to the hydrophobic property, it also becomes very heavy when wet (it “holds” all the liquid) but that means it “pulls” that moisture from the skin.

Another issue with Merino wool is its price – due to the high demand and cost of growing Merino sheep ethically, Merino wool tend to be very expensive – roughly twice more than regular wool and 3-4 times the price of man-made fabrics. Merino is also very easily damaged due to how fine it is – Merino garments are known to have holes in them in places of high friction.

Merino wool comes from a specific breed of sheep (Merino sheep) that originated in Portugal. Today Merino sheep are grown everywhere in the world, but New Zealand is probably the most well known for their quality of Merino wool and the ethics that they apply to growing sheep.

The differences between Merino wool and regular wool are:

• Merino wool is much finer than regular wool – it has a much lower micron and so is thinner in diameter.
• Regular wool is coarse – Merino has much smoother surface of the actual fibre, making it less itchy.
• Merino wool is flexible– the finer Merino fibres are more flexible and has a little elasticity to them.
  

What about other fibres?

Obviously the main “competition” Merino wool has is not with regular wool, but with other fibres such as: silk and synthetic fibres (cotton is a big no no when it comes to the outdoors, just don’t use it), so how does it compare?

•  Merino vs Silk – Silk is also a natural fibre, much smoother and softer than silk. Silk is strong but has no elasticity, insulation properties and low moisture retention. The lack of elasticity and insulation properties makes not useful as a baselayer (to keep moisture away from the skin) of for a midlayer (insulation). Silk is useful as a liner fabric to keep the skin comfortable and as a barrier to other fabrics. A good combination will be silk liner socks with Merino socks over them to maximize comfort and function.
• Merino vs synthetic – The most commonly used synthetic fibre (in the outdoors market) is polyester – it is cheap to make, light, robust, can be hollow-fibre (insulating) and is hydrophobic (won’t absorb water). At first look it is a much better fabric than Merino, but it has a few drawbacks in comparison: first, polyester is not anti-microbial, so it will smell very quickly in repeated use. Second, the hydrophilic property means it will dry with anything on it, and that means that if you sweat/get dry several times, salt will dry on the fabric an it will become itchy (ever sat on your bathing suit after the beach for a while? same thing). Last, polyester doesn’t have the soft and natural feel that Merino has.

What is the bottom line?

Merino wool is a great fibre, but it is not magical, nor it is very performance focused. It is soft, comfortable, functional in low impact activities and will work great on longer (a few days) activities. Personally, I use Merino a lot, but when it comes to any situation where I will be sweating a lot and need to dry fast, or when I know I will end up being wet a lot, I prepare a synthetic based garment.

For me, Merino wool is the perfect multi-day low and slow fabric, but when it is time to get fast and sweaty, synthetic always wins. Do you have other experience with it?