Arc’teryx Atom SL Hoody Review

I can’t think of any product families more versatile or better-loved than the Arc’teryx Atom family. They’re a friend to everyone from extreme mountaineers to college students in the drizzly Northwest, and for good reason. It’s a tremendously versatile family, and with the Atom SL as the newest addition Arc’teryx is cutting into one of the hottest territories in the gear world today – active insulation. We’re talking about gear that you leave on all day, while working and while resting, that can adapt to any situation.

Arc’teryx Atom SL Features:

• Insulation: Coreloft Compact 40 synthetic insulation
• Shell: Tyono 20D shell with DWR treatment
• Side Panels: Torrent fleece stretch with Polygiene (84% polyester, 16% elastane)
• Polyester mesh-lined sleeves
• Front zipper features No Slip Zip
• Adjustable Storm Hood
• Unlined, zippered hand pockets
• Drop back hem
• MSRP: $229

Designed with an atom’s precision

Let’s talk about the Arc’teryx Atom family. Their previous models were both a tad heavier – the AR being heaviest and the LT being lighter. The LT and the SL share common uninsulated side panels that dump hear, while the AR is fully insulated all the way around. The jackets also feature a common insulation, Arc’teryx’s proprietary CoreLoft. This is a type of active insulation, in the same class as Polartec Alpha, that’s designed to breath during exertion but retain heat during rest. So here’s what Arc’teryx is trying to accomplish with the new Atom SL: let’s make a jacket that climbers, runners, mountaineers and backpackers can leave on all day and forget about. It needs to be able to breathe well enough to put up with exertion, and then dry out (if you’re a heavy sweater) and keep you warm when you stop to rest or flake ropes or whatever it is. That’s what we’re shooting for with the Atom SL.

The jacket is, in in typical Arc’teryx fashion, exceptionally sleek. It’s a svelte, slim-fitting piece that’s designed to function both as an outer layer in mild conditions while layering seamlessly beneath shells or puffies. The basic layout looks like this: two zippered hand pockets set high for harness compatibility, fleece-lined gusseted underarms and sides for breathability, a NoSlip front zipper, a tall chin guard on the collar and a one-way adjustable hood. The face fabric is a 20D nylon with Arc’teryx’s Nu DWR, the inner mesh is 20D polyester and the side panels are a polyester/elastane blend. The advantage of this fabric combination is pretty obvious – the exterior nylon face is durable and soft while the inner polyester mesh has natural wicking performance brought on by the polyester’s hydrophobic properties. The result is a sort of mechanical wicking, bringing your sweat directly into the mesh to be carried away by the face fabric. It’s good to see a full nylon shell fabric: that translates into more durability in the long run. Holding it all together is a light ‘No Slip Zip’ front zipper, which I was somewhat baffled by. It’s not a locking zipper so you can use it with one hand easily. That’s great, but contrary to the name I found that it did slip when I was running in cold weather in the jacket.

I’m 5’11”, 185 lbs. I tested a large Atom and it fits perfectly. It’s snug around the waste, nicely fitted around the shoulders and without excess on the arms. I tend to run hot during activity, so something like the Atom’s light core insulation works for me when it’s very cold outside or my activity level is only moderate. The Coreloft insulation for the SL is at 40g/square meter), while the LT and AR have 60 g/square meter and up to 120 g/square meter, respectively. The AR actually has zoned insulation at several weights. The SL clocks in at just over 9oz, shaving off around 3 oz from the LT model. I think it’s worth noting that Coreloft, Arc’teryx’s proprietary insulation, doesn’t loft as well as something like Primaloft Gold. I have Primaloft pieces and couldn’t notice a substantial difference, but it’s hard to compare different weight and ages of jackets. Regardless, it works well.

Running throughout the sides and underarms is an elasticized, breathable fleece. This is retained from the LT and it offers epic levels of temperature management. The wind cuts right through it, but that’s intention – these are active pieces. Rounding out the rest of the jacket, the hem features a nice drop back for added coverage and the hood is one-way adjustable. The hood is an interesting design; it doesn’t have the nice, face-hugging profile of the AR or LT but it still features a nice tall collar to snuggle your face into. I wish there was a small fleece chinguard, but that’s absent from all of the Atom models.

It’s worth talking about what this jacket is not designed to do. It’s not a rain jacket. It’s not a puffy. It’s not a baselayer. It’s not a fleece. People trust the Arc’teryx brand, but sometimes they expect their products to do more than they’re actually designed for. Certainly it’s versatile, but it won’t keep you warm or dry like a dedicated shell or puffy will. That’s kind of obvious, but it’s worth mentioning. People keep asking me if you can use it in a downpour – no, despite the Arc’teryx logo, you’ll still get wet.

So what is this jacket really good for? Well, it’s good for high-output athletes who need a precision instrument to take into the mountains. You’ve got to be using this in conjunction with a good system, for one thing – it’ll keep you very comfortable on the Northwest’s volcanoes in the summer, but if something goes wrong and you need to be sedentary then you’d better be sure that you have a puffy ready. However, if things are going well and you’re in a good rhythm of climbing, resting and climbing then this jacket can really save you time. In the right conditions it removes the need for switching or adding layers during transitions in activity. Its lightly insulated core will keep you warm, and importantly it handles sweat well enough that you shouldn’t build up significant moisture in the fabric to steal your heat. It also has a strong DWR (Arc’teryx’s proprietary Nu treatment) that’ll fend off light precipitation. Naturally, it works best when you’re keeping a constant level of activity to expel moisture and prevent the fabric from getting bogged down.

In practice, the Atom SL is a joy to use. Like all of the best pieces of gear, it disappears when you’re wearing it. Every detail is in place, from the slightly extended cuffs to the thoughtfully designed minimalist hood. The fit is particularly refined, with the drop hem adding a lot of protection and contributing to a sleek fit. The polyester mesh fabric and the Tyono nylon face fabric work well together to manage moisture and temperature. Even the pockets, which can be a weak point in many an otherwise good jacket, disappear with their low-profile zipper pulls and careful placement.

The Good

• Excellent overall design
• Minimalist, but still fully functional
• Coreloft insulation, coupled with mesh and fleece paneling, rock at moisture management
• Fit is trim and feels almost individually tailored

The Bad 

• No Slip Zip slipped quite a bit during my testing
• Hood design is good, but can become a windsock with no option to stow it away

The Bottom Line: Arc’teryx Atom SL

Like I said, this is a precision piece. It’s good for athletes that know their body and know how they work during their particular activity. As a mountaineering guide, I really like this piece for my guided trips because it helps me cope with the different abilities of my clients; I can trust one piece to protect me over a wider range of levels of exertion. It gets my thumbs up.

Buy Now: Available from Backcountry.com

In Summary

9.2 Super Refined

Flexible insulation is key here. The Arc'teryx Atom LT offers excellent warmth over a variety of conditions. I've used and trusted this atop the volcanoes of the Pacific Northwest and it is so comfortable to wear, I find myself looking for excuses to wear it.

• Breathability 10
• Water repellency 9
• Fit and tailoring 10
• Feature quality 8
• Construction quality 9