The Jottnar Yak Wool Challenge....

3rd Feb 2016

jottnar uller

A few weeks ago Jottnar contacted me to ask if I’d be willing to take part in their ‘Yak Wool Challenge’  which would involve, they explained, wearing one of their Uller yak wool baselayers continuously for a week and commenting on it’s qualities along with how smelly it got when wearing it over a long period. 

I’ve worn and admired Jottnar’s clothing for some time (and I’ve written reviews of several pieces here), but I wasn’t initially sure this challenge was for me.  I only accept review offers of products I feel suit my needs and I have struggled with some wool base layers before due to their itchiness.  I wondered if I’d really find the Uller wearable.

Before committing I decided to do some research.  The closest I’ve previously come to yaks was being nearly nudged off a Himalayan path by one that was loaded up with duffle bags, but I soon found out that despite their renowned toughness these majestic animals have wool with potentially amazing properties.

The magic of yak wool…..

It turns out that many believe yak wool to be superior to sheep wool in a number of significant areas (the following information comes from a variety of sources including Wikipedia).

Yak wool is warmer than sheep wool and keeps you warm when wet - In woollen garments, air pockets are created between the fibres reducing the rate of heat transfer. This property, combined with the hydrophobic grease lanolin, allows wool to keep you warm when wet. Yak wool is rich in myristic acid which is a hydrophobic fatty acid and tests on yak down have suggested it could be between 10% and 40% warmer than sheep wool (results vary according to which sources you use).

Yak wool is extremely soft - Cashmere is known in the textile industry as one of the softest wools with a diameter of less than 18.5 microns. The diameter of Yak fibres also ranges between 16 and 20 microns making its softness comparable to that of cashmere.  In comparison, medium Merino is between 20 and 23.  

Yak wool has great breathability - Wool’s comfort comes from its thermo-balance characteristics and the breathability of a material depends on its ability to absorb moisture relative to its weight and then release it into the air.  Wool can absorb over 30% moisture which is greater than cotton at 25% and far greater than polyester which can only absorb 1% of its weight.

Yak wool has natural odour resistance - Yaks do not have a strong odour and their sweat, unless combined with bacteria that lives on the skin, is odourless. The anti-microbial properties of yak fibers prevent bacteria from living on sweat  and so this considerably reduces odour.

The Jottnar Uller is constructed from a blend of yak wool and synthetic fibres to combine the unique yak wool qualities with the hardwearing qualities of synthetic fibres.  Jottnar say the Uller will hold its shape far longer than 100% woollen garments while still retaining the yak wool properties.

So, it sounded like a yak wool baselayer would be comfortable enough to wear while also standing up to the rigours of an outdoor life.  I contacted Jottnar and told them I was in!

The Jottnar yak wool challenge……

The arrival of the Uller baselayer conicided nicely with my latest stint in the eastern Highlands.  I had seven continuous days on the hill on a mixture of mountaineering and skills courses.  I also had a snow shelter night which always provides a chilly test of wicking and warmth qualities.

The Uller arrived and we were almost good to go although before committing fully I wanted to check that I would find the Uller wearable.  I needn’t have worried.  As soon as I took it from the wrapper I could feel that this was something special.  The fabric is so soft that it feels almost too luxurious for outdoor use.  I pulled it on and loved the fit and simple detailing.  This challenge really wasn’t going to be a hardship…..

Day one begins tomorrow.  Please watch this space!

The Jottnar Yak Wool Challenge

Day 1

Fiacaill ridge resized

In comparison to some of the Highlands weather I've experienced recently, today was forecast to be a fine and calm day turning to rain later.  So pleasant, infact, that I wondered if I might be too warm in the Jottnar Uller.  I needn't have worried as things are rarely as predictable as you'd hope in the Scottish winter mountains - it turned out to be a blowy day with high wind chill turning to calmer and warmer weather later.  

I pulled the Ullar on at the start of the day and layered it with a Patagonia R1 Hoody and Rab Strata Hoody.  Later a Rab Event hardshell prototype jacket was added over the top.  It was a toasty combination that suited a stop and go kind of day.  

I was struck straight away by how comfortable this base layer is - it feels really luxurious next to the skin and is a great fit.  The neck comes up high enough to feel cosy but isn't too tight or restrictive.  Jottnar always work hard to create great fitting garments and this is another great fitting product.

The objective for the day was a classic mountaineering adventure on Fiacaill Ridge with John and Luke.  We trudged through heavy snow patches and I was definitely feeling damp by the time we arrived at the ridge.  Normally, however, this dampness would turn to a chilled feeling but I am happy to say the wool layer soon felt dry again and this continued throughout the variable temperatures of the day.

So far, I love everything about this yak wool layer and there is no sign of a pong yet.  Roll on tomorrow's adventure :)  

Day 2


A new group arrived in the Cairngorms for the latest round of winter skills courses last night.  We chatted through the plan for the coming few days and discussed equipment.  Of course, I showed some of them the Jottnar base layer as a good example of what they might wear and extolled the virtues of yak wool for anyone who’d listen!

Today we were to have a ‘shake down’ skills refresher day as all the participants had been on previous courses and so we simply needed to ensure they were at a good level before progressing their skills.  We headed up through the ski area and found some areas to play.

For today my Jottnar base layer was paired with a Rab MeCo mid layer and a midweight Mountain Equipment Shroud fleece and Rab Neo Guide shell.  The walk up to the ski area is a steady slog over tussocky grass and the Uller kept me toasty warm and, although it got a little damp, it soon dried out once we stopped.  For the bulk of the day this was going to be a day where we stayed fairly static for some time and so I now required my layers to keep me warm in a different way.  The Uller was, again, simply brilliant.  This layer feels warm and snug all the time.

At the end of the session we dropped down through the ski area and made our way back to base.  All that remained was too peel off the outer layers and assess the smell.  Result!  There still wasn’t any!  Ready for day 3.....

Day 3

crampons snow

The Scottish mountain day dawned and, being a Saturday, we headed up to the ski area carpark early to get parking space in anticipation of a busy day.   Infact, it was surprisingly quiet and we needn’t have rushed.  I layered up in the Jottnar baselayer, a Rab MeCo mid layer, Patagonia Nano Air vest and Rab Neoshell hard shell.  Infact, it was a lot colder and windier than expected and I was a bit worried I might soon be dipping into my spare clothes.

I really needn’t have worried as the system worked really well again.  The Jottnar continues to be really impressive - comfortable, regulates heat well, breathes efficiently and, as I can again testify when I removed it this afternoon, is smell free.  I am really loving this garment and the yak wool challenge isn’t, as it stands, a challenge at all!

Day 4

snow shelter digging

It is fair to say that Scotland has had an up and down winter.  There have been some great hill days and some stinkers, soggy damp to the core days and crisp sub zero peaches.  A fairly typical Scottish winter and yet one that has certainly made it important to make good choices and made having the right equipment essential.

Today was a really grim Cairngorm day.  Low temperatures combined with high winds and driving snow (later turning to rain) to give a really frigid feel to the day.  We did what every self respecting winter mountaineer does when conditions are so grim….we dug!  The team constructed some amazing emergency and planned shelters and had a great time.  Even so, this sort of activity always means you’ll get damper and damper as the day goes on.  

I got through 3 pairs of ‘waterproof’ gloves and was pretty damp by the time we navved back to the ski area.  Even so, I am impressed to say that I still stayed plenty warm enough in the yak wool layer and, although damp at the end, I didn’t feel uncomfortable.

As I enter the fourth day of the Jottnar Yak Wool Challenge I can say I am, without exception, really impressed by this garment.  It is hard to put a finger on what is so special about it - but it just works really well.

As for the smell? Tonight I asked a few clients to take a sniff of the top.  Always a tricky thing to ask and a question that I always leave until I have got to know people reasonably well, but I really needn’t have worried - the feedback was that the baselayer, even after four continuous days of use, was pong free.  That is….pong free and ready for day 5!

Day 5

Fiacaill Ridge

We deserved it.  We really really deserved it!  Today dawned calm, the winds had dropped, the temperatures stayed low and the clouds had disappeared.  It looked to be one of those Scottish winter days you really dream of.  

I have been out with Gary and Stewart today and after 2 days with skills supremo Hannah they were well prepared to tackle something a bit more technical.  The avalanche forecasts suggested a ridge would make a good choice and so we headed for the all time classic of Fiacaill Ridge.  This majestic route splits the main Cairngorm corries and, particularly on a clear day, the position and the route itself are very very hard to beat.    

For today I was wearing the Ullar yak wool layer paired with a Patagonia R1 Hoodie and Patagonia Nano Air Vest - this proved to be a great combo for the cold and crisp conditions.  I did have a worrying moment when I went onto the drying room at the start of the day and was hit by the heady stench of rancid clothing but I realised, when I got my own stuff out and back to my room, that it wasn’t any of my kit that was contributing to the pong.  The Jottnar baselayer was also, amazingly, smell free.

We had a ball on the ridge and the boys were able to pick up a lot of skills for their future adventures as well as us enjoying a simply stunning mountain journey together.  Scotland sometimes makes you wait and wait, but get a day like this and you forget the grim ones that came before.

By the end of the day the Jottnar was still dry and comfortable although I could detect, as I peeled back the layers, a slight ripeness to the top.  Hardly surprising after 5 days of constant use, but I took it off and left it for a while to air.  Tomorrow I will be back in the Peak District so time will show whether the whiff remains……

Day 6


A long drive south last night saw me leaving behind fine weather in Scotland to battle the winds and rain of the A9, M74, M6 and the various other north to south arteries.  It was extreme driving -  but I made it more comfortable by not changing from the various layers of outdoor clothing I’d worn the day before.  This meant the Uller Yak Wool base layer had had a very long day and I put it onto a radiator to air once I arrived back at Peak Mountaineering HQ.

After the treat of a bit of a later get up I was ready for action - action in the office and, once a few emails were sorted, action on the mountain bike.  Cal dragged me and my weary legs around a nice Mam Tor loop in lovely Peak District weather.  It was chilly but great for biking so I wore the Uller baselayer, a midweight Mountain Equipment fleece and a lightweight Patagonia cycling jacket.

Again the baselayer performed faultlessly and, although I got hot and sticky on the climbs, I soon got back a decent temperature once the energy output eased off.  Once I got home the Uller smelt fine - a little musty and definitely with a 'well worn' smell…..but still fine.  Tomorrow is the last day for the Uller challenge and yet I feel this layer could really go on and on without a wash.  I look forward to giving my final verdict tomorrow.

Day 7


The last day of the Jottnar Yak Wool Challenge dawned dry and fine in the Peak District. I crawled from the comfort of my bed and reached for the Uller base layer which had been airing overnight.  This wasn’t really going to be the ultimate test for a hi tech garment as I was combining a morning in the office with a journey to pick up a new vehicle.  Undaunted, I decided to wear the Uller as planned and use the test as an incentive to have a decent length run later in the day.  

Of course, the office session went as well as expected and the trip to collect the vehicle didn’t provide much of a challenge (although we used the journey to create the ‘My Way’ masterpiece (!) featured later!).  Once back from all the chores I headed out to the local Derwent Valley to run a loop of Ladybower Reservoir.  It was a lovely day and a pleasure to be out.  Needless to say that the Uller coped brilliantly as expected.

Once back at home I stripped the layer off to make a final assessment.  The results were very very impressive.  There was, after 7 days of use, only a whiff of a ‘lived in’ smell.  I decided to give it a wash but really it felt it could have carried on like this for ages (or maybe forever?!).


The Jottnar Uller Yak Wool base layer is a very impressive garment and has delivered on all counts.  It has kept me warm, wicked away moisture superbly, stayed smell free, been extremely comfortable (I normally find wool itchy and this hasn't felt like that at all).  It is also a stylish base layer that feels like it will last well.  So, as with all the previous Jottnar products I’ve tested, this ticks all the boxes and would score an A* in any exam.

There is actually nothing at all not to like except it’s price tag.  Jottnar produce premium products and don’t scrimp on quality - you pay a premium for this.  The Uller costs £90 and, had Jottnar not kindly sent me this one to test, I would have found the price hard to justify unless I was sure the  performance justified the cost.  Of course, most times you can’t actually find this out before purchase and are left to trust reviews or word of mouth recommendations.  So, all I can say is that I would buy another Uller even at the price.  It is a superb performer and I look forward to many great adventures together.  You will not be disappointed with this garment. 

And finally, to sign off the Jottnar Challenge, here is the song we wrote on our journey to that VW garage.  Yes we had too much time on our hands and yes it is very closely related to the famous My Way.  But we hope you enjoy it anyway…….


The Yak Wool Way   


And now, the end is near;

And so I face the Yak Wool Challenge curtain. 

My friend, I’ll say it clear,

I’ll state the case for the benefits of yak wool, of which I’m certain.


I’ve used it in many ways,

I’ve climbed winter routes and cycled highways,

And more, much more than this,

I wore it my way.


Regrets, I’ve had a few;

Like the day I forgot to put my hood up (in a snowstorm).

I did what I had to do

And saw the challenge through without exception.


I planned each charted course;

Each careful route to winter heaven,

And more, much more than this,

The Uller baselayer kept me comfortable (and pong free!).


Yes there were times, I’m sure I told you,

When I over layered and was cooked through and through,

But through it all, the yak wool coped,

It ate it up and spat it out.

It faced it all and it stood tall,

It did it the yak wool way 


I’ve loved it, I’ve laughed and smiled,

When around me colleagues struggled for warmth,

And now, as the challenge subsides,

I find it all so impressive.


To think that it did all that,

And may I say - not in a shy way,

“On no, oh no not with difficulty.

I did it the yak wool way.


For what is a man (or woman), what has he/she got?

If not an Uller baselayer, then they have naught.

To say the things they truly feel; 

It’s a super high performance baselayer.

The record shows it took the blows -

And did it the yak wool way! 


Full details on the Jottnar range can be found here and the Uller is featured on their website here.

Posted by Paul

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