Since launching KUIU in April, we have been an...

Since launching KUIU in April, we have been answering a lot of  questions regarding our merino program; why Merino and not synthetic? How KUIU’s compares to our competitors? In the following post I put together information on Merino wool and The Merino Company to help you understand merino and the advantages of KUIU’s Merino wool products.

After leaving Sitka, I spent over 18 months researching and testing fabrics for the KUIU line. This study of fabrics led me to Merino wool as the only base layer choice for back country hunting. Intrigued by this fabric and process I dug deeper into understanding merino wool and found not all Merino is the same.  There is a quality and consistency difference in merino from the open global market versus buying directly from the farm that produces it.

The Merino Company has this distinct supply chain advantage over all other suppliers that guarantees a higher quality fabric. The Merino Company with offices in Australia and New Zealand has been in the Merino Wool business for well over 15o years.  They have long established relationships with Merino growers in New Zealand, South Africa, Australia and South America.   This ensures The Merino Company consistant access to the finest quality fibers and the knowledge of where each fiber of their fabric originates from, who’s growing it, how the sheep are handled and raised.  Every other Merino supplier buys their fibers on the global market with NO knowledge of where their fibers come from.

“The TMC approach ensures there is minimal variation in wool quality throughout a supply chain, with transparency, traceability and tight controls from sheep to shelf (S2S).”  states TMC


Wool is a natural, renewable, sustainable and biodegradable fibre, and much like human hair is made of keratin.  Keratin is a tough, insoluble protein with a unique structure it has a natural resistance to sunlight, water, acids, rot and mildew under most normal conditions.

Wool is expressed in microns, the unit of measurement used for the fibre’s diameter. One micron equals one millionth of a metre. The lower the micron of a fibre, the finer it is, and the finer the wool the softer it is next-to-skin. Wool fibres vary in diameter from 11 – 60 microns. Merino fibres are the finest of all wool types and are usually less than 24 micron. An overview of micron ranges:

Strong – or broad – wool: 23 – 24.5 microns

Medium: 19.6 – 22.9 microns

Fine: 18.6 – 19.5 microns

Superfine: 15 – 18.5 microns

Ultra fine: 11.5 – 15 microns.

To make a comparison, human hair is about 100 microns.

Merino is unique in its ability to keep you warm in the cold of a snowy winter, and cool in the heat of a humid summer, protecting the microclimate next-to-skin in changing conditions by absorbing and releasing moisture.  The core of a Merino fibre is hydrophilic (water retaining), and is breathable, moving perspiration away from the skin so that you feel cool, fresh and dry during exertion.

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 fibres, and as Merino is much finer than most other textiles, it contains more air spaces, and provides greater insulation.

Merino is naturally odour 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 odours. Sweat itself has no odour, but if it is allowed to remain on the skin, bacteria will develop and so will body odours. Merino fibres 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 fibre.

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. 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.

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.

I hope this information is useful in helping you better understand the advantages to Merino Wool and The Merino Companies supply chain quality advantages.  I look forward as always to hearing your comments.


This article has 36 comment(s)

  1. beau purvis

    Thanks to this site and Jason I tried some merino last winter. I will not wear anything but merino next to my skin now. It is very comfortable. More importently , it completely controls my body odor for multiple days.

    • Jason Hairston

      Hey Beau, I am so glad to hear this!


  2. Matt

    This is one of the reasons I LOVE KUIU! The willingness to explain the reasoning behind a select fabric and the education you provide to your customers. I’m new to using Merino Wool as base layers and I can tell you from experience I will not miss the funk left behind from synthetic base layers. The other advantage to wool that that has really drawn me in is I don’t have to carry multiple changes of clothes because I can’t stand myself due to the odor of synthetic after one or two days. Win Win for the week long backpack style hunts. Not sure anyone can beat what Mother Nature has provided…. that being wool.

    • Jason Hairston

      Hey Matt,

      I totally agree, Merino has some HUGE advantages to Synthetics for back country hunting. I am glad you found this write up useful. Good luck this season!


  3. Michael

    BIG FAN of merino-As mentioned previously- Your merino would make a phenomenal ball cap!

    • Jason Hairston

      Thanks Michael. Our hat supplier is looking into this for a ball cap.


      • Michael

        Jason= Thanks very much! I am looking forward to that becoming my “go-to” hat
        I appreciate the time.

        • Jason Hairston

          You got it!!


      • Michael

        The MAJOR Brown or camo would be AWESOME.
        thanks again for listening-

        • Jason Hairston

          Again, thanks for the input Michael!!


  4. Alex Hoover

    Is it machine-washable?

    • Jason Hairston

      Hi Alex, yes it is machine washable.


  5. Jeff M. Valunas

    As you are aware, I always love ‘school time’, from you and KUIU, explaining the Great products you are bringing us! This is just the fix, I need, while awaiting fall to roll around, to get out there and hunt in this stuff! I have been using the Merino Zip-T 185 as my shirt, for my training hikes here in Tucson. Even when the temp sores to nearly 100 F, I feel very comfortable. And when that shirt dries, I can slip it on late at night in the cool evening air, and not only feel great, but not have a hint of smell. Merino Wool, is AWESOME. KUIU, provides the best, I have found! Keep it up buddy!

    • Jason Hairston

      Hey Jeff,

      I am glad to hear you enjoy the technical information. There is always a bit of concern that I will bore most. Thanks for the feed back and I am so glad to hear you are liking your Merino.


  6. Mike P

    I love my merino shirt…have worn it 5 or 6 times so far and have not washed it as a small experiment to see how long it will go without stinking…so far so good. I have a 50 km trail running race this weekend in the mountains and the temps are expected to be high so i am planning to wear the KUIU and see how it does for the race 🙂

    When i wear my synthetics i usually stink after one day of exertion so the merino has beat that easily already.


    Mike P

    • Jason Hairston

      Hey Mike,

      I have put mine through the test as well, so many straight days that my wife would not sit next to me. Not because the shirt stunk but because she thought I was gross for wearing the same shirt for this long for any reason. I did not tell here about the merino boxers I was testing:)))


  7. Alvaro from Spain

    very interestin read, indeed, Jason, thank you!

    how does merino properties compare to those of other natural fibers like cashmere, mohair, and vicuña? maybe their high prices, specially those of vicuña wool, make them impractical, but are they any superior to merino?

    I always carry a cashmere pullover in my pack and it is a delightful garment to wear for its softness and warmness.

    • Jason Hairston

      Hi Alvaro,

      I can comment on Cashmere, it is an amazingly light and a fabric due the the ultra-fine fibers as you know. It has a very small micron rating, below 13m from what I remember (could be wrong here). The down side to Cashmere is expense and durability. These ultrafine fibers do not have durability or abrasion resistance which is why they are not used in hunting gear (except for you :). In my testing I do not recommend going below 17.5m.


  8. Curt Cabrera

    I used mine all of May during turkey season here in NY. I wore it as a base layer on chilly mornings with more KUIU layers over top of it as needed. And, as a stand alone layer in weather as hot as 80-85 degrees.
    I was amazed at how comfortable it was! I purposely washed it very few times to see how it felt putting it on after sweating it up pretty good the previous times I wore it……I admit it felt a little better when it was squeaky clean, but even when it was way overdue for a wash(not unlike a long backcountry hunt), it was very comfortable against my skin….I love KUIU Merino wool!!!

    • Jason Hairston

      Thanks Curt! I always appreciate your feedback here on the blog!


  9. Ken Allen

    I just did a 5 day 40 mile back country hike and wanted to test the difference between the wool and synthetic. I alternated between the two for the first three days and the wool won hands down for smell and comfort. I won’t be taking the synthetics again.

    Thanks for introducing me to wool. My impression had always been that it would be too heavy and uncomfortable. Every time I take a step forward and improve my gear its a confidence builder.


    • Jason Hairston

      Thanks Ken! This is great to hear!


  10. John

    Once you go wool you won’t go back to synthetics. I just bought a pair of merino wool briefs… (they don’t need to be camo)

  11. Neil

    Hi Jason,
    Us Aussies have used this fabric in hunting for years. It is definately the best layering fabric in the world with the added bonus of managing your odour. Generally it is avaliable in a plain colours so having it in camo would be great. I think the key here is producing the right weight of fabric… For my base layers I use a pant that has hot zones. These zones are located in the areas that you legs and butt get cold first or more regularly. For example the knees always get cold as do the to of your thighs, shins and back of the calves. The only problems I have found is at times the elastic fails after some heavy use. I hope to see some great designs from KUIU with wool.

  12. J.R. Young

    I wore my 185 up to the Los Altos Rod and Gun club on the top of the Santa Cruz Mountians. Anyone who knows the area, understands the battle that goes on between the cool pacific air and the warmth of the Santa Clara Valley.

    I arrived and it was 58, foggy and damp. Within an hour the winds picked up, the fog burned off and it was 80 in no time. I was fine thoughout the whole change. While others were dropping layers I was comfortable throughout the change. I’m looking forward to putting it though the “funk” test when the A-Zone opens up later this month, and really put in though the test on a 12 day hunt in Northern BC.

  13. Brennan

    Sounds like the boxers are in development? I think the boxer brief style works the best for backcountry hunting. Look forward to seeing the new stuff coming out.

  14. Rob B

    Hey J, great stuff again. Any time line on when you would be releasing the schoeller style waterproof outerwear? I need a new jacket but am really holding out for a waterproof breathable from you with pit zips and in olive drab. Thanks again,

  15. Suburban bushwacker

    Another shout for the merino ball cap, in fact one in each colour

    Nice work chaps

  16. Matt Willis

    Merino wool seems to be the answer to all the questions, why not use it for all garments instead of just the base layers? Thanks!

    • Larry Schwartz

      Because merino wool by itself won’t cut the wind or keep the rain out. They use the right tool/materials for each job.

  17. Mike P

    Just used my KUIU Merino while doing the Sinister 7 Ultra Trail race and it worked great. My wife ran the race solo ( 148 km) and i ran with her for the last 50 km fo the race, I had the shirt on for my base layer and it was 23 celcius when i started and down to 2 degrees celcius at 2 am on top of a mountain and it regulated my temp better than any of my synthetics…the best part was that even after 50 km of running my shirt smells like its still brand new 🙂

    Used the Merino Beanie for my hat and it worked great for regulating my head temp as well. Also used my Guide Gloves as well and they worked great.

    Just need the KUIU merino boxers, KUIU merion boxers and some KUIU Attack shorts and we will be all set for racing 🙂


    Mike P

    • Jason Hairston

      Hi Mike,

      Congratulations! Do you have any photos you could send us? I would love to post them up or do a blog post about you in this race wearing KUIU. Thank you so much for sharing I am so excited to hear the gear performed.


  18. John Ford

    Jason, any plans in the future to do maybe some heavier wool items for mid-layers or even a sweater for outer wear/insulating garment? I know a wool sweater is not light weight, but a medium weight one is great for insulating or even outer layer in fair to mild temps. Thanks for a great product and the weekly promotion !!!

    • Jason Hairston

      Hi John,

      I am looking at some heavier weight wool fabrics. The down side is the weight to warmth ratios and staying in the Ultra-Light mantra of KUIU.


      • John Ford

        Thanks for the reply. I know it does not quite fit the Ultra-Light plan, but you have such great quality wool I had to ask. Thinking of setting in a tree here at home in Kansas and how nice a good wool sweater can be. I hoped it might fit into an insulating layer for colder climates. I have a thin merino wool sweater that is pretty light and is extremly warm.
        By the way the camo is fantastic for the praire country of Kansas.

        • Jason Hairston

          Thanks John! I appreciate the feed back.