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Review: Alpkit Koulin Trail Base Layer

Man ice climbing

A versatile, comfortable, high-wicking and breathable base layer that just plain refuses to stink up!

If you want an affordable base layer that gives you everything you’d expect from a far pricier competitor (and even a bit more!), the Alpkit Koulin is a pretty damn good place to start looking. It’s light, breathable, super-comfy and works well in a number of activities. And because it’s treated with magical Polygiene, it’s designed to stay stink-free for longer than your average base layer.

But did it meet our reviewer’s very (very) high standards for mountain-going undergarments? Read on to find out…!

Alpkit Koulin Trail base layer: The stats

Fabric:100% Polyester Polygeine Technology webbing
Style:Long-sleeved, zip-neck base layer
Machine washable:Yes
Warranty:3 years
Colours:Nemo, Chilli, Fontainebleau

Design features of the Alpkit Koulin Trail base layer

Long zip neck

Zip neckThe high neck keeps the draft out when you need a little extra warmth but zips open when you need some ventilation. The zip pull tucks nicely inside a flat at the top to stop it irritating your chin and neck.

Polygiene treated fabric

Polygiene logo
The polyester fabric is treated with Polygiene Permanent Odour Control which does an exceptional job at keeping the stink at bay. Made from recycled silver from electonic waste, the treatment helps prevent bacteria, fungus and virus growth within the fabric. And if they can’t grow, they can’t smell. Clever stuff! So clever, in fact, that the treatment remains effective for the whole life of the top — no re-treating needed.

Mesh side panels

Mesh panel of shirtTo help maximize breathability, there are mesh panels under the arms. These also eliminate the need for a seam (and potential chafing) in the armpits.


PocketAt the back of the Koulin is a wee pocket with a folded top to pop in your small essentials. (Snacks, keys, money etc).

Flatlocked seams

Seams of base layerThe flatlocked seams further prevent any potential for chafing and discomfort to create an almost seamless feel.

Alpkit Koulin Trail base layer review

I think this review might be best started with a bit of a confession. I am human and, as such, am blessed (blighted?) with underarms that, given the chance, tend to get a bit whiffy given time. When I head into the outdoors, moreover, I tend to see that time as a welcome release from many of the non-negotiable strictures of life in the city. One such stricture is the socially de riguer insistence on showering, bathing and generally optimal personal hygiene. On a long thru-trek, I could gladly go for a week without having so much as a drop of water grace any part of me.

This is all very well if I’m on my lonesome but can, understandably, become irksome to whoever happens to be my tent buddy if not. In the past I’ve used various means of staving off the stench and avoiding the necessity of impromptu bathing in some frigid pool: a deodorant stick, rubbing myself with wild garlic (I kid you not) and once, when very flush, splashing out on a trio of eye-wateringly priced merino base layers recommended by, you guessed it, my tent buddy. The deodorant and garlic, alas, were no match my for my oxters. The pricey merino numbers, though promising at first, lost marks (and much of their utility) when I stuck my thumb and/or fingers through them or proceeded to disintegrate of their own accord after only a few months of occasional usage.

Koulin Baselayer

Arriveth the Alpkit Koulin base layer. On first impression, this base layer all too much resembled an old, trusty Berghaus affair I’d pinched from my dad and worn religiously until informed that if I did so again I’d be sleeping on my lonesome. I had, moreover, expected small odour-eating panels in the armpits or Glade-like plugins that would squirt plumes of ‘Alpine Meadow’ freshness into strategic locations throughout the day. None of this was in evidence, and yet the makers boldly claimed their product to be ‘Odour Free’. I sensed a challenge, one for which I and my armpits were born. The shirt came with a 123-day returns policy – I doubted I’d need as many as three.

Day one: climbing

After an hour-long approach and two hours of climbing at the top of my grade and sweating commensurately, I was delighted to find that I’d suffered none of the rueful nipple-rub that I’d experienced with other base layers and suspected might result of wearing another synthetic product after so long with my holey merino. The Koulin was comfortable, soft against the skin and, at the end of the day, surprisingly odour free. My nipples, moreover, were none the worse for their interactions with non-organic materials.

Day two: ice climbing

Today the Koulin formed the first of five layers and was mildly drenched after my frozen extremities had convinced me to keep on all five for the first two pitches of a steep ice climb, despite my partner warning me that I’d soon be working up a sweat. I then shed my down jacket and by the top of the third pitch found myself dry again. In the car on the way home, I stripped down to the Koulin alone and spend the whole hour-long journey awaiting my partner’s complaints. They did not come, and a quick poke of my beak into my oxter revealed that if they had, they would have been entirely groundless.

Ice climber

Day three: hiking

I set off in snowshoes at 6:30 am and returned to my car just as the sun was setting some ten hours later. I’d covered 1,450 meters of ascent and slogged through temperatures ranging from -8c to +7c. A few times the shirt popped out of my belt and I wished it had been made a little longer, but then remembered that my physique is fairly odd (my torso is longer than most) and there was a bit more of me to cover after Christmas-time excesses, too. Otherwise, the shirt’s performance was very pleasing. It wicked sweat quickly, provided ample warmth beneath my top layers and, somewhat gallingly, smelled fresh as a daisy upon my return to the car. I was beginning to lose hope.

Day four: trail running

Now I meant business. Three days without washing the shirt and no shower that morning. I ran for an hour, sweating buckets and returned home sure that I’d finally done the job. I dropped the Koulin on the floor to marinate in its own fumes while I took a shower. When I returned, it was fresh enough to substitute my towel. Soon, it seemed, I’d be substituting that towel for a white flat…

Day five: work

I work in a nearly all-female environment, one where such faux pas as less-than-perfect hygiene are not often ignored. I have been chided for mismatched colouring in the past. For wearing the same shirt two days in a row. For a five o’clock shadow that, by my watch, has barely passed noon.

The Koulin raised a few eyebrows, to be sure, taking pride of place above my standard get up of chinos and brogues, but this was the test that would settle things, one way or the other. Maybe, I thought, my climbing and hiking partners and I had become so accustomed to my smelliness that we were simply immune to it. My nearest co-worker, however, is immune to nothing. Misses nothing. Not a thing. She has been known to file missing molecules reports for absent iotas of dust. She keeps track of my sock changes. She can smell coffee breaks to which she was not invited a whole hour after the fact. She hones in on the scent of dirty plates left lying in the tea-room before their contents have been fully swallowed. A bear in a former life, perhaps, in this one she is a one-woman CIA, KGB and MI5 combo for anything so much as fractionally out of the ordinary. If my four-day unwashed shirt had so much as a whit of a whiff to it, she’d notice. She would, moreover, be sure to let me know.

“No time to iron a shirt today, love?” she asks me as I enter the office.

“Eh, yeah, something like that,” I reply. I sidle into my chair and am suddenly more grateful than ever for the six-foot divide between our desks.

The day passed as most do. The central heating is, as always, turned to a setting better suited to a winter’s night in the Arctic Circle than a spring day in the Gulf Stream’s epicenter. I delight in the airy breathability of my new threads as the sun climbs above the neighbouring buildings and turns the room into a sauna.

My persnickety colleague and I meet at the coffee machine later. Her famous nose is within twelve inches of my unwashed raiment and she doesn’t even flinch. At one point she even touches my arm to ask me to pass her a spoon. I’d expected her to be swooning, gagging, calling HR. Instead she seems blissfully unaware that the very shirt upon which she laid her regularly sanitized finger has not been near soap and water for four days and several sweaty hours.

At the end of the day her head appears from around her computer screen. She calls my name. I have, alas, had it. The ruse of the odour-free shirt has been exposed and the potency of my axillary lymph glands confirmed. I shuffle timidly to her desk, preparing myself for a barrage of sanitation-shaming and a dressing down. She looks up at me, poker-faced, that ultra-sensitive, homing device of a beak glimmering in the glow of her desktop.

“The shirt isn’t bad, love” she says, “but I really don’t think it goes with the shoes.”

Man ice climbing

What I love about the Alpkit Koulin Trail base layer

In a few words, it’s comfy, odour-free and costs around a third of what I’ve paid in the past for similarly performing but far less durable merino base layers. It wicks moisture very well and provides just the amount of insulation I like from a next-to-the-skin undershirt. I also like the fact that when worn alone it doesn’t, like many other base layers, resemble a Civil War era troop’s undershirt and is snazzy enough to stand alone (even if my colleague doesn’t think so).

What I don’t love about the Alpkit Koulin Trail base layer

Beyond undermining my claim to the title of smelliest armpits ever, the unlovables about the Koulin are few and far between. I was, as mentioned earlier, ever so slightly put off by the shirt’s lack of length. Generally speaking, I always look for a base layer that will tuck into my trousers and not pop out if I’m cutting shapes on the rock. As I also mentioned above, however – and should stress again – I do have a fairly oddly shaped body and have this problem with most upper body wear. Next time I’d simply shoot a size up.


All in all, the Alpkit Koulin Trail Long Sleeve base layer is a cracking piece of kit that I imagine will serve me well for many a year to come. It breathes well, wicks sweat no bother and is very comfortable. And, despite my best (worst?) efforts, its Polygiene treatment is mightily stubborn in its refusal to stink up. Less washing, more wearing. A definite keeper.

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Disclaimer: Cool of the Wild received this product free in return for an honest review. We only recommend gear that we love from companies we trust and we are under no obligation to give a positive review. All thoughts and opinions are that of the reviewer and we are in no way influenced by the brand or company.

About Kieran


Kieran is a nuttily-passionate climber, mountaineer, trekker, trail-runner, and all-round lover of wild places. He has spent most of his life doing cool things in the Himalaya, Rockies, Dolomites and the Italian Alps, where he now lives and spends his time stomping trails, clambering up crags, ticking-off peaks and, occasionally, sleeping (with reluctance!).

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