Until synthetic insulation, down feathers were the primary insulation used in sleeping bags and puffy jackets.
Down feathers offer powerful warmth, but they have a weakness: moisture. A new type of water-resistant down insulation addresses this weakness, and we’ll discuss its benefits in this article.
Temperature and weather are two of the biggest obstacles to any outdoor activity. Much of the gear that we use either protects us from weather or helps us regulate temperature—and some do both. Until recently, down feathers were the primary insulation used in sleeping bags and puffy jackets. Down feathers offer powerful warmth at a nominal weight, but they do have a weakness: moisture. Much of the power of down insulation comes from the warm air trapped among the fine plumes inside the baffles of your sleeping bag or jacket. Rain or overly humid weather can dampen these feathers, causing them to clump and lose loft, and thus, the opportunity to trap warmth is lost.
Moisture is a tricky force of nature. Over the years, the manufacturers of sleeping bags and jackets have used waterproof breathable shell materials and water-resistant material coatings to mitigate the effect of external moisture on down, but often these solutions result in moisture trapped within the down baffles. You sweat during sleep or activity, and even the most breathable materials can’t stop the dampening effect of this moisture passing across the down insulation. Even extreme humidity affects down; the very moisture content of the air passes through the breathable material membrane and finds its way, slowly, into the down insulation. Before long, your sleeping bag is rendered damp and you, cold.
At the heart of this battle with moisture is the very nature of down feathers. Down feathers are light and easily affected by any amount of moisture due to their inability to repel this very same moisture. Even the physical abilities of water, like capillary action, work further against the down, allowing even the smallest amount of water to flow across the fine, textured face of a down feather quickly. Here, a necessary solution comes in the form of a water-resistant or water-repellent coating not for the material that contains the down, but for the down itself. Enter: water-resistant nanomolecular coatings.
Water-resistant down is simply down insulation treated with a water-resistant coating at a molecular level. Before the down is packed into the baffles of a jacket or sleeping bag, each feather is treated with a special nanomolecular coating that allows the feather to resist moisture (also called a hydrophobic coating). Because this coating is applied at such a micro scale, it adds almost no weight and it doesn’t affect the ability of the down feathers to loft, so there’s no lost warmth either. And unless you’re traveling into extreme weather conditions, there’s no need for a waterproof breathable membrane or water-resistant coating for the material that’s used to contain the down feathers.
Among the early adopters of water-resistant down insulation are brands that make sleeping bags, down insulated jackets, and down-insulated cold-weather accessories like mittens, booties, and more, including Sierra Designs, Mountain Hardwear, Big Agnes, Rab, and FlyLow. More are joining in every year, so you can look for more availability, and potentially lower prices, in years to come.