The Arcteryx Atom SL Hoody Review

A Guide’s Review of the Arc’teryx Atom SL Hoody

The Atom is a staple of the Arc’teryx line. Walk around any Canadian mountain town on a cool day and you’re sure to see half a dozen people wearing one. They have a durable water resistant outer with just enough synthetic insulation to keep you warm. However, the Atom Hoody may be a little too warm during high output exercise.

Enter the Atom SL. It sits at the light end of the series and is built for moving rather than standing still. The stretchy Fortius Air 20 shell, Coreloft Stretch body insulation, Octa fleece under-arm panels, and uninsulated arms and hood all point to one purpose: high-output days in cool weather. Speed hikes, trail running and cool to warm ski tours are where it does its best work.

Arc’teryx Atom SL Key Specs

Outer: Fortius Air 20 nylon
Insulation: Coreloft Stretch, 40gsm
Breathable Panels: stretch Octa Fleece side panels
Weight: 327 grams measured
Origin: Bangladesh
Size + Color Tested: X-Large, Forage

How I Tested the Arc’teryx Atom SL Jacket

I’ve had the Arc’teryx Atom SL jacket for about six months and have taken it throughout the Alps from Spring overnights in huts, through heatwaves and now on training hikes in the Sea to Sky area. It’s been a great companion to have throughout this time knowing it adds a touch of warmth, a little weather protection and would never be too hot.

Outer Layer

The outer of the Atom SL is made of Arc’teryx’s own Fortius Air 20. This recycled outer is made of 84% nylon and 16% elastane so it has a good amount of stretch. It also has an FC0 DWR that does not contain intentionally added PFAS.

The 20 in Fortius Air 20 is the denier of its nylon yarn: 9,000 meters of the yarn weighs 20 grams. A yarn this fine helps keep the Atom SL lightweight. This is a delicate material and makes the Atom SL a layer I would not choose to have exposed while smashing through the bush on a hike. It will easily handle brushing past rocks but I would avoid spots where your jacket may snag.

The FC0 DWR treatment does not contain any PFAS. it can handle a small mist of rain though iIt will not handle a downpour. This is not a rain jacket nor is it meant to be. For that, you’ll want to look at something like the Beta SV.

Warmth and Breathability

The Atom SL wears like a lightly insulated vest married to a windbreaker. It has a lightly insulated core, breathable fleece panels and uninsulated arms and hood.

The Coreloft Stretch in the main body handles the insulating duties. It is a synthetic batting insulation that is found in all of the Atom jackets but at different thicknesses. The SL has 40 gsm of insulation and the next warmer jacket, the Atom Hoody, has 60 gsm. The difference is noticeable, especially when motoring uphill. I own both and would never venture to go for a fast hike in the regular Atom, the Atom SL will readily come for the hike.

Thanks to the Fortius Air 20, the jacket breathes exceptionally well. Octa fleece mesh-lined side panels let heat out when you’re working hard but add some warmth once you stop.

As a result of all this breathability, the Atom SL isn’t a warm jacket for standing around. Once you stop moving in still air, the fill runs out of steam quickly. This can be a double-edged sword. Not great if you are on the verge of being too cold already but great if you are overheating and want to cool down without removing the jacket.

It has been proven fantastic on cooler days where I know I am not going to spend a ton of time on the summit. Temps around 10 Celsius or below. A moderate pace uphill met with ten minutes of downtime at the summit. I dry out just a little enjoying the view and then warm up just a smidge on the down.

Arc'teryx Atom SL — Close-up of the Octa Fleece side panels

The Fit

The cut is loose athletic. I have the XL version and find it fits right in the sweet spot between baggy and tight. Its stretch and fit give it a casual look while still being mountain capable. The body fits just below my waist line and the arms stay at my wrists at full reach. On the top of the cuffs is Fortius Air 20 material while on the inside is small strips of elastic to keep the cuff snug.

The hood has a slightly beefier elastic that runs around the entire opening. At the top of the hood is a small amount of stiff tubing to help it keep shape. The Fortius Air 20 is just too soft and flexible to stay put on its own. At the back of the hood is a shock cord and cord lock that help pull the hood away from the sides. This is not a hood designed to go over helmets but will easily fit under one as it is just simply two pieces of Fortius Air 20.

There are two hand pockets lined with Fortius Air 20. The hand feel is soft enough that it is comfortable on bare hands without having some type of fleece lining. This would only add warmth and weight, which isn’t the ultimate goal of a Super Light jacket.

At the back right of the jacket, just above the buttock, is the sole hem adjuster. This pulls a cord that only goes around the back of the jacket from Octa fleece panel to Octa fleece panel. It pulls the jacket in just below the wearer’s backside and leaves the front flat. I neither like nor dislike the change from a cord that reaches farther around.

Wingspan test on the Arc'teryx Atom SL — Wingspan test on the Arc’teryx Atom SL

Weight and Packability

At 327 grams, it packs small. The left pocket can be inverted to become a pouch for the jacket. There is a loop for attaching the jacket to a carabiner on the outside of your harness as well. This is an easy way to travel with the jacket and should be included on every midlayer ever made. Honestly though, I find shoving the Arc’teryx Atom SL into my vest or pack to be better use of the space. It allows the jacket to fill up space rather than take up space and makes for faster deployment.

Durability

This is where the Atom SL asks for trade-offs. The Fortius Air 20 is a thin fabric and is not built to shrug off bush bashes, it’s built to dance between them. My copy shows no wear from my backpack and its waist and chest straps. It is not that fine of a fabric. However, I was in the Brenta Dolomites the third time I wore it. I ran to take cover from an approaching cold front at a barn and took a seat at an old wooden table. I stood up quickly and teh jacket caught on a large splinter that proceeded to pull a loop of material out of the jacket. I thought it was done for (read: small pull. I’m over reacting). I was going to cut it loose and accept the new vent but my wife was somehow able to massage it back into place. I cannot find where the pull was anymore.

Elastic on the inside cuff of the Arc’teryx Atom SL

Who is the Arc’teryx Atom SL Hoody For?

I have been super happy with the Arc’teryx Atom SL. It’s a great addition to my arsenal of being able to stay warm and dry on full value days in the mountain. I often find myself putting it on before hitting a pass knowing that it will be windy, my sweaty back will make me cold the moment I stop. I know I won’t overheat on the last fifteen minutes up with the Atom SL and I will need a layer that will keep me out of the wind and neither cooling nor overheating as I relax and enjoy the view.

The Atom SL Hoody is one of the most useful (and packable) pieces you can own. Wear it as a standalone layer when trail runs take you through cool weather or layer it with a waterproof shell when mountain pursuits demand a little additional warmth. It’s lightweight means you can bring it along for when the weather teters between warm and cool and you just might need a little extra warmth.

Interested in picking up an Atom SL Hoody. Head on over to Arc’teryx Canada or to Arc’teryx USA to pick one up.

…DISCLAIMER…

Black Sheep Adventure Sports was provided with a free sample of the Arc’teryx Atom SL jacket and pants. This in no way affected our opinion and review. This post also contains affiliate links; if you choose to purchase gear through these links, we may earn a small commission which supports our independent testing at no extra cost to you.