Jack Wolfskin Seamless Wool Long Sleeve review: a light yet warm base layer you'll forget you're even wearing

Meet the reviewer

Julia Clarke

Julia Clarke is a staff writer for Advnture.com and the author of the book Restorative Yoga for Beginners. She loves to explore mountains on foot, bike, skis and belay and then recover on the the yoga mat. Julia graduated with a degree in journalism in 2004 and spent eight years working as a radio presenter in Kansas City, Vermont, Boston and New York City before discovering the joys of the Rocky Mountains. She then detoured west to Colorado and enjoyed 11 years teaching yoga in Vail before returning to her hometown of Glasgow, Scotland in 2020 to focus on family and writing.  

Jack Wolfskin Seamless Wool Long Sleeve: first impressions 

Base layers are an essential item for hiking and winter sports, but they're not all created equally. Some are too heavy, some get too stinky on sweaty pursuits, and others still can't quite ditch the itch of wool. We've been testing the Jack Wolfskin Seamless Wool Long Sleeve on hikes in the Scottish highlands, the Lake District and the English lowlands for the past couple of months and found a lot to love about it.

First off, it's ultra-lightweight and has a precise fit, so it's easy to layer and move in, and it's not too warm if the weather turns mild. The blend of merino wool and polyamide isn't scratchy on the skin and has great thermoregulating properties, keeping you warm and dry if you get sweaty on cold days. It doesn't get stinky quickly, so it's good for a few adventures thanks to the merino content, but the synthetic fabric means it's a little more durable than a straight merino top.

The seamless circular design means that there are no seams on the torso (there are, of course seams on the sleeves) and that may reduce chafing for those who struggle with it. Either way, it makes for a flattering design and has loads of stretch for comfort in movement.

The only real flaws we could find were the lack of thumb holes (though the performance fit means it's easy to layer without them) and it is on the pricey end for a base layer. The quality certainly means you can expect some longevity out of this top, and we love that it's light enough you can roll it up and stuff it in any bag whether you're going backpacking or hopping on a plane for an active adventure.

Jack Wolfskin Seamless Wool Long Sleeve: in the field

I pretty much live in base layers and I'm always looking for ones that I can wear across multiple adventures that keep me warm and dry but aren't too warm or bulky. I've been testing this out for a couple of cold months in the Scottish mountains as well as on some recent adventures down to the Lake District where I went forest bathing and South Downs National Park on a foraging expedition.

Here’s how it performed:

Sizing and fit

I usually wear a small but I was sent an XS by Jack wolfskin and it actually fits quite well, probably because it's so stretchy. I think I probably err on the side of wearing everything a little loose, for comfort, but I think a small would have been perfect for me, so I wouldn't necessarily recommend sizing down.

The fit of this base layer is really flattering, thanks to the circular design and the crew neck keeps a cold draft out without being annoying. Also unlike a lot of similar base layers, the sleeves seem to be the right length and I don't have tons of extra fabric bunched up around my wrists, though it does bunch slightly on the wrist where I wear my watch.

Weight and comfort 

Next to my Black Diamond Long Sleeve, this is the lightest base layer I own, which I really like. Though I do prefer a thicker wool layer during the coldest days, this design is far more versatile, so I can wear it on its own when it's mild and layer up with a fleece when it's cold. I don't even notice I'm wearing it when I have lots of layers on, and it rolls up really small so I didn't even think twice on bringing it along as an extra layer on a recent press trip to the South Downs.

I can't say that I've ever really noticed the seams on a base layer, but this one is certainly comfortable, mostly due to the fact that it's not at all itchy despite the wool content and also the stretch (I was able to wear it for a chilly yoga session during a glamping trip). As I said, I barely notice I'm wearing it, so what could be more comfortable than that?

Thermoregulation and odor protection

Even though adding synthetic fabric to a natural material merino means you jeopardize its capacity to biodegrade, it's hard to deny that the blend offers the best performance when it comes to temperature regulation. I've tested this out on some steep climbs and never felt too warm, so I know it breathes well, wicking away sweat and drying quickly too. That said, it's also enough to keep me warm when it's really cold out and I have a warmer jacket on top.

Synthetic tops get really smelly with a single use, but this one has enough merino that it lasts for a few adventures without needing washed, which means it's lower maintenance and helps balance that sustainability component.

Jack Wolfskin Seamless Wool Long Sleeve: the bottom line

This long sleeve has earned a coveted position in the top three base layers in my drawer and its lightweight performance means it's easy to grab if I want a backup. The lack of thumb holes may be a deterrent for some, though not for me personally, while I do recognize that the price tag won't be for everyone. For a high-performing lightweight style that's a little easier on the wallet, check out the Black Diamond Long Sleeve Rhythm in comparison.

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