Patagonia Merino Air Base Layers – Super Warmth and Top Breathability

Patagonia Merino Air Base Layers - Super Warmth and Top Breathability 1

Back in the day, everyone wore wool sweaters to stay warm Maybe we need to pay more attention to our elders – seems everything old is new again. What the hell am I talking about? I’m talking about how Patagonia took the wool sweater and updated it with a merino/Capilene blend to make their new Merino Air base layers. They’re simultaneously the warmest and most breathable/best wicking bases we’ve seen.

Patagonia Merino Air Base Layer

Look – I know we’ve been excited about a lot of Patagonia’s gear recently. It’s not because we’re fanboys. It’s because they’ve been innovating the crap out of outdoor clothing. They’re not the only ones, to be sure, but they’re probably the most visible and the most vocal about doing what they do with the environment front and center. When Patagonia moves, the industry moves with it. When they move in the right direction – both in performance and responsibility – we support it wholeheartedly. So, yes, we’ve been excited about Patagonia. We think there’s a good reason.

The Fabric

With that out of the way, let’s get back to the Merino Air. What makes it great? Well, if you look at all of the “reviews” out there, everyone parrots Patagonia’s marketing talk about how their yarn is spun from merino wool and recycled Capilene polyester using a proprietary process that makes it loftier than other merino blend yarns. Want to know how? We took a deep dive into the Google and found out that Patagonia uses air jet-spun yarn. Air jet spinning does a better job of integrating the wool fibers into the yarn, which increases abrasion and wear resistance and decreases pilling. Air jet spinning does a better job of wrapping the wool around the core fiber than other spinning methods. (If you want to read more about air spinning, have at it!) Essentially, what it means is that Patagonia’s supplier feeds the recycled Capilene fibers into the spinning machine and the air jets wrap the merino fibers around the Capilene fiber. Capilene is a hollow-core fiber, so when the merino is wrapped around it, you end up with a loftier fiber.

Patagonia Merino Air Base Layer

The technique isn’t unique. NuYarn is manufactured the same way and is similarly thicker than a non-hybrid yarn. When we test out some NuYarn gear, we found it to be thicker than similar weight fabrics – more warmth per weight.


Where Patagonia differentiates the Merino Air pieces, however, is in the creation of the fabric from the fibers. While NuYarn pieces sewn together from separate pieces of woven fabric, Patagonia uses computer-controlled knitting machines to knit each Merino Air piece as one – no seams, no separate panels. What looks like seams on the Merino Air gear are knit transition areas. They stretch and move just like the rest of the fabric. Patagonia chose to knit in a 3D, zig-zag pattern that makes the fabric much thicker than a woven fabric of similar weight. Thicker means more loft means more warmth for the same weight. So, while Merino Air fabric weighs 190g/sqm, it feels like it’s about three times as thick as a woven, 190g merino blend. The knit pattern also means moisture and air move through the fabric better than a typical woven fabric, so you dry faster during high-intensity activity.

Merino Air is 51% merino, 49% recycled Capilene polyester. Patagonia’s merino comes from sheep in the Patagonia region of Argentina and Chile. There was some hoopla in 2014 about how some of the source farms were treating sheep. You can read about how Patagonia is working to resolve that issue here. The Capilene polyester core fibers are made from soda bottles, manufacturing waste, and recycled polyester garments. Learn more here.


Patagonia offers the Merino Air series in Hoody, Crew, and Bottoms. The Crew and Hoody are entirely seamless. There are two small seams at the crotch of the men’s Bottoms to incorporate a fly and the elastic waistband is sewn on. Women’s bottoms are entirely seamless and use a woven waistband. Because Patagonia knits their Merino Air gear in as single pieces, both the Crew and Hoody lack a zipper. The Hoody’s hood is close-fitting – like having a balaclava attached to your shirt. It can cover your face if needed.

Patagonia Merino Air Base Layer

How We Tested

Between our two testers, we’ve had the Merino Air Hoody in every situation from skinning up in the backcountry to shredding back down in the backcountry and resort to standing outside in wind chills around 0°F on top of the Eiffel Tower. (because, why not?). For one tester, Sean, the Merino Air hoody and crew have become the only thing he wears. He apologizes for it. I’m not sure why. For me, I can’t imagine wearing something else as a base right now. And, I will admit to having worn a bright orange Merino Air Hoody in the Louvre. The fact that people thought I was French while wearing the Hoody tells me it passes fashion muster in addition to functioning well.



We’ll break this down – my opinion first and then Sean’s. We pretty much agree that the Merino Air is awesome.  Sean did a video overview.  Watch it and then scroll down for our written opinions.

Dave: The Merino Air really does perform as promised. Back to back with a traditional merino blend base (180g, 18.3 micron, so a bit lighter), Merino Air is more comfortable and felt warmer and dryer. The knit creates air pockets against your skin so when you do get sweaty, you don’t have a wet base layer stuck to you. I get very sweaty. Merino Air feels much better than traditional, woven base layers.

I’m in love with the hood. It fits like a balaclava when it’s up and acts as a neck gaiter when its down. That eliminates at least one, possibly two pieces of gear that I would normally bring with me on a tour or for a day in the resort.

I also didn’t miss having a zipper, although I thought I would. I’m usually the guy with a zipper open down to my navel trying to dump heat. With a Merino Air base and a breathable insulating layer (in my case, Black Diamond’s First Light Hoody), I was feeling comfortable skinning up in temps ranging from 0° to 30°. Above that and the insulation comes off. Haven’t been up in temps below that.

I picked the orange for visibility purposes. I always choose bright colors so I can be seen in the mountains. I’m also on the receiving end of good-natured ribbing about it, constantly. Don’t care. I like the orange. And, as I said above, it passed fashion muster in freakin’ Paris. Or maybe the French just thought I was odd. I’ll accept that conclusion is equally plausible.

Sean: First, it just feels perfect. It is like wearing a fluffy cloud that moves with you and keeps you comfortable. The hoody is super light too. Just 8oz for my XL. The fit is athletic but not restrictive at all. I found the XL to fit perfectly on my 6’1” 200lb frame. The combination of 18.9-micron wool and polyester fabric coupled with the unique zigzag pattern create a really comfortable garment that you just have to try out to understand. It is unlike any other base layer I’ve seen.

The balaclava-style hood that is very useful when you’re spending time in the mountains. I found it saved my head on many backcountry tours! At first, I was a bit off put by the look of the hood as it was scrunched up when not in use, but I quickly got over that. If hoods are not your thing, then grab the crew neck version and have all the same features and benefits of the Merino Air without the hood.

The fact that the hoody is so comfortable and does not tend to stink led me to wear it for days on end, much to the dismay of my wife, who pleaded with me to change my shirt. So I picked up 3 more. Now I just live in these all week.

Final thoughts

Especially on sale, Patagonia Merino Air pieces are a no-brainer. You’re paying at least $110 for a nice merino-blend base from anyone else (not counting the Costco ones, but at 11% merino, they shouldn’t count). Even at full price of $149 for the Hoody, $129 for the Crew, $129 for the bottoms, performance is such a leap over other base layers that Merino Air is worth the premium. You don’t have to buy four of them (cough-Sean-cough), but you should definitely grab at least one if you spend time playing in the mountains during the winter and want the best base layer on the market.



Leave a Reply