When John Barklow designs a new product, I get excited. The big game product manager for Bozeman, Montana-based hunting brand Sitka began his career as a diver in the Navy, before moving on to teaching outdoor survival skills to SEALs. Then in the early 2000s, during the War on Terror, Barklow began designing clothing systems for Special Operations Forces soldiers. His big innovation at this time was to recognize that in extreme weather outdoors it is often impossible to stay dry, so clothing designed for these conditions should dry as quickly as possible.
If you’ve worn highly breathable mid layers like Polartec Alpha, or taken advantage of a garment system that combines synthetic base and mid layers with a soft shell, you’ve likely benefited from Barklow’s expertise. But the designer had not yet turned his attention to sleeping bags.
Barklow brought two major innovations to the new Sitka Aerolite 30 ($ 400). It is the first sleeping bag to use the latest synthetic insulation from Primaloft, and it is the only time a designer has subjected a bag to the testing procedures of the International Organization for Standardization (ISO), as well as to layers of specific clothing. This gives the Aerolite two major advantages. Even when it’s completely wet and completely compressed under your body weight, its insulation is still able to keep you warm; and Barklow can prescribe a specific set of diapers that allow you to take the bag well below its rated temperature, while still sleeping comfortably.
Together, these innovations allow the Aerolite to function outside of the limited role traditionally filled by sleeping bags. Rather than just keeping you warm while you sleep, the Aerolite also doubles as an outer layer of clothing to help keep you warm during static activities, and it dries your other layers while you wear it.
âThe sleeping bag is the last part of your clothing system,â says Barklow. âIt’s your last line of defense against the cold; it is your armor against the elements.
The Aerolite uses the new Primaloft Gold insulation with Cross Core. Like other synthetic insulations, Primaloft Gold’s loft is not compromised by moisture, which means it stays warm when wet. Synthetic fiber insulation approximates the weight and compaction ability of down, and its fibers contain Airgel, a very porous and very light material which is one of the best insulators ever created. Thus equipped, the fibers that make up this insulation are able to trap the hot air inside, which means that even when the material is completely compressed, it still insulates.
âThe insulation in the bag excels in wet conditions because of the airgel trapped in each fiber,â says Barklow. “The physical loft of the insulation will be compressed by the user in some areas, but the air trapped by the mechanical design of the airgel will remain and provide heat.”
To determine the nominal temperatures (comfort, extreme and limit), manufacturers of sleeping bags subject their products to ISO 23537 test procedure. The test dictates a sleeping pad with an R-value of around 4.0 and equips the test dummy with a set of lightweight base layers. Consumers can then cross-shop bags on the basis of comparable data.
In ISO 23537, the Aerolite achieves a comfort rating of 38 degrees, a limit rating of 28 degrees and an extreme rating of zero degrees. Barklow also took the bag through this same test in the same lab with different layers of clothing. Since the official ISO testing procedure only allows these lightweight basecoats, it points out that its layering requirement for specific colder temperatures does not carry an official ISO certification.
To provide you with insulation equivalent to a comfort level of 20 degrees, Barklow recommends using light base layers, a Polartec Alpha mid layer, a light puffer jacket, softshell pants, an insulated beanie, rubber gloves. lightweight fleece and insulated slippers. To reduce this to ten degrees, base layers should go up to medium weight items, baggy should become thicker, and equivalent baggy pants should be added. Articles suggested by Barklow are his designs for Sitka. You can replace them with similar choices from other brands, just like you can still stack them in any sleeping bag, but achieving equivalent performance will depend on your own trial and error.
The Aerolite’s limited temperature rating, along with these layering guidelines, illustrate the role the bag is intended to perform. It is specially designed to be used with your clothes, so you can carry a smaller, lighter bag and get the most out of the rest of those clothes.
âA technical clothing system should work for you around the clock and provide additional insulation when you sleep,â says Barklow.
By equipping the Aerolite with zipped armholes, a fitted jacket-style hood and a two-way zipper that opens to the footrest, as well as a hook that stores this rest -feet up and out By the way, Barklow’s intention is for the bag to replace a hi-loft parka in your loadout. Wear the bag over your other layers, not only for sleeping, but also while hanging out around the camp. Light precipitation is wiped away by the durable water repellent coating on the rugged 20 denier outer fabric, and it doesn’t seem to impact the performance of the bag if some of that moisture ends up inside the insulation.
It will also work to dry your diapers overnight, whether they are wet with sweat or completely soaked in the rain. Like the rest of Sitka’s garment systems, the bag is designed to take advantage of the heat generated by your body to keep moisture out, even in the harshest of conditions. Inside several layers of shells and insulation, the heat your body generates creates a build-up of pressure. Inside this system, this heat dries each subsequent layer and continues to push moisture outward until every component is dry. Sitka specifically designs its different layers to facilitate this process.
“I ended up in the bag completely wet and almost completely dried by the morning – eight o’clock,” Barklow told me. He and other Sitka testers have tested prototypes of the Aerolite for the past two years, until its release in July.
I just returned from using the Aerolite on a seven night trip over the Arctic Circle in the Alaskan tundra. The area is basically a huge soaked sponge and it rained continuously throughout the trip, with temperatures ranging from mid-20s to 30s. There, outfitted with a 5.7 R-value cushion and Barklow’s recommended clothing system for a 20-degree comfort rating, I was toasty every night of the trip. Even though I got into the bag late at night with damp clothes and often wet socks, I was never drier than when I woke up each morning.
However, one thing the Aerolite isn’t is that it’s hot on its own. At least not at temperatures below 40 degrees. Without a new bag to test, I would usually have packed a traditional down mummy bag with a comfort rating of 15 or zero. By crawling in there at night, I could have shed all my diapers and always been warmer than I was in the Aerolite. But, I couldn’t have reached this heat so easily. Because even treated down loses its loft when wet (waterproof treatments can allow it to dry faster), using a down-insulated sleeping bag in a humid environment dictates an exceptionally careful approach in which you have to go to great lengths to protect the bag from moisture. You should be careful to pack and carry the sleeping bag in a dry bag, put it in place and let it inflate well before bedtime, and most importantly, you cannot get anything wet, or even wet, nearby. . This usually means carrying an extra set of base layers, a pair of socks, and a warm hat, just to wear when you sleep. An accident like dipping a down sleeping bag in a stream or letting the rain seep into your tent can be a disaster. None of these disadvantages apply to the Aerolite. It’s as foolproof as a sleeping bag can be, as long as you’re ready to layer up when you sleep.
Barklow acknowledges that the Aerolite won’t be for everyone. âPeople who run after every ounce, or those who don’t recreate themselves in dynamic climates, may choose a different bag or insulation,â he says. If you just want a sleeping bag that you can crawl into and feel warm with little or no extra layers or strain, Sitka’s new bag isn’t for you. But, people who go outside on a mission, who don’t want the weather to slow them down, may find the Aerolite uniquely capable. “This bag allows the user to stay focused on why they are out and about and not worry too much about the weather.”