Sleeping bags with a waterproof design

A new product designed by John Barklow always gets me excited. His career started as a diver for the Navy then he taught outdoor survival techniques to SEALs before moving to Sitka, a hunting brand based in Bozeman, Montana. He then developed clothing systems for Special Operations Forces soldiers during the War on Terror in the early 2000s. When those conditions are present, clothing made for people in those conditions has to dry as quickly as possible; that was his big innovation at that time.

Barklow’s expertise is evident in highly breathable midlayers like Polartec Alpha, or clothes systems that combine synthetic base layers and midlayers with a softshell. Sleeping bags were not yet on the designer’s agenda.

With its new Aerolite 30 ($400), Barklow introduced two important innovations. Among its features are Primaloft’s newest synthetic insulation, and the test procedures that International Organization for Standardization (ISO) has instituted for evaluating bags and clothing are unique. Its two main advantages lie in that. The insulation of the bag will keep you warm even if fully wetted out and fully compressed under the weight of your body; and Barklow can prescribe a set of layers that will allow you to use the bag well below its temperature rating while still sleeping comfortably.

The Aerolite with these innovations can do more than just fulfil the limited role that sleeping bags traditionally play. Besides keeping you warm during the night, the Aerolite also works as a piece of outerwear that keeps you cozy during static activity, while drying out your other clothing layers.

Barklow says that a sleeping bag rounds out your clothing system. You need that as your last line of defense against the cold, as your armor from the elements.”

This Aerolite model features Primaloft Gold Insulation with Cross Core. The Primaloft Gold loft isn’t compromised by moisture like other synthetic insulations, so it remains warm even if wet. Synthetic fibers offer the same weight and packability as down, but they contain Aerogel fibers, which are very porous, very light, and the best insulation ever developed. As a result, the fibers that make up that insulation are able to trap warm air internally, ensuring that even when the material is fully compressed, it maintains its insulation properties.

Aerogel encapsulated within each fiber boosts the bag’s insulation properties during wet conditions, according to Barklow. Despite being compressed by users at certain points, the trapped air remains in the Aerogel, causing warmth to be generated.

As the Aerolite can be worn all around camp, without fear of wetness or rain, you have one more advantage: It can be warmed up easily before you sleep, just by wearing it. Brinlee, Chris Jr., photo

Sleeping bag manufacturers use the ISO 23537 test procedure to determine their products’ comfort, extreme, and limit temperature ratings. As part of the standard test, the test mannequin is equipped with light base layers and a sleeping pad with an R-Value around 4.0. By using like-for-like data, consumers can cross-shop bags.

As per ISO 23537, the Aerolite has a comfort rating of 38 degrees, a maximum rating of 28 degrees, and a maximum of zero degrees. During the same lab test, Barklow also tested the bag with different clothing layers. He stresses that he cannot certify his layering recommendations for cold temperatures since official ISO testing only allows those light base layers.

The author recommends wearing lightweight base layers, Polartec Alpha midlayers, insulated beanie, light fleece gloves, and insulated boots to provide equivalent insulation to a 20-degree comfort rating. It would require a transition from base layers to more midweight pieces, a thicker puffy, and equivalent puffy pants to get the temperature down to ten degrees. Barklow’s designs for Sitka are the items he suggests. In the same way that you can layer up inside any sleeping bag, you can also substitute those products for similar ones from other brands, but achieving the same level of performance will depend on your own trial and error.

This layering guide accompanied by Aerolite’s limited temperature rating illustrates the bag’s role. With this bag, you carry a smaller, lighter bag, so you can utilize the rest of your clothing more effectively.

During the night, a technical garment should provide additional insulation when you sleep.

Barklow intends to use the Aerolite bag in place of a high-density parka by equipping the bag with zipper-open arm holes, a hood that zips up and a net that can tuck the foot box away. Wear the bag over your other layers, not only to sleep, but also while you’re hanging around camp. The water-repellent coating on the 20-denier face fabric sheds light precipitation, and the insulation doesn’t seem to be harmed if some of that moisture makes its way inside the bag.

Your layers will also stay dry overnight, whether they are damp from sweat or completely soaked from rain. In addition to simulating your body heat, the bag is designed to keep moisture coming out of your skin even in the worst conditions. Heat generated by your body builds pressure inside multiple layers of shells and insulation. Each subsequent layer is dried by that heat, and moisture is constantly pushed outward until every item is dry. Sitka’s various layers are specifically designed to facilitate this process.

Barklow tells me, “I was wet when I got into the bag, but had dried out almost completely by morning, eight hours later.” In the two years leading up to its release in July, he and other testers at Sitka have tested prototypes of the Aerolite.

Sitka’s new sleeping bag (in the green bag) next to Sea to Summit’s Spark SPII. The Spark utilizes 850-fill down rather than synthetic insulation, and 10 and 7D shell fabrics rather than Sitka’s more robust 20D fabrics. Weight differences between the Aerolite and the Spark are 38 ounces versus 17.3 ounces.

My first trip with the Aerolite was above the Arctic Circle, on the tundras of Alaska. We spent the entire trip in an enormous, soaking wet sponge, and it rained continuously. Temperatures ranged from mid-20s to high-30s. The Barklow clothing system and my R-value pad enabled me to remain warm every night during the trip. While I often woke up wet and drenched in the bag each evening, I was always dry the next morning.

Aerolites do not come warm on their own, however. In temperatures under 40 degrees, at least. As a rule, I would pack a traditional down mummy bag that has a 15- or zero-degree comfort rating if there were no new bag to test. While I was bundled up in the Aerolite in the evening, I could have thrown off every layer and still been warm. It would not have been as easy for me to achieve that warmth. Even treated down loses its loft when wet (waterproof treatments may make it dry faster), so using a down-insulated sleeping bag in a wet environment requires some very careful preparation in which you must take every precaution to keep the bag free from moisture. Make sure that the sleeping bag is packed inside a dry bag, that it’s set up and allowed to loft well before bedtime, and that nothing wet or damp gets near it. In order to improve your sleep, you must carry an extra pair of socks, a pair of hats, and a set of base layers. Getting wet in your tent or submerging your down sleeping bag in a stream could cause you great harm. The Aerolite does not have any of those shortcomings. So long as you layer up when you sleep, it can be as foolproof as sleeping bags get.

Barklow acknowledges that not everyone will like the Aerolite. “People who chase every ounce, or those who don’t live in dynamic climates will choose a different insulation or bag,” he says. Sitka’s new bag is not for those who just want to crawl into it and feel warm without adding multiple layers or exerting much effort. Aerolite is designed for people going outdoors on a mission who don’t want weather to slow them down. By using this bag, individuals can concentrate on the reasons they are out in nature instead of worrying about the weather.”

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