In cold weather, the trick to staying warm is layering with the right insulation, and not all insulation is created equal.
While the type of jacket you need has a lot to do with the activity you’ll be doing, learning a few basics about the different types of insulation, and waterproof technologies, will go a long way in choosing the insulated jacket best suited to your needs.
There are two main types of insulation used in jackets: down and synthetic. Both have specific strengths and weaknesses, making each superior in certain situations. Regardless of the type of insulation, the basic principle that keeps you warm is the same. Air and body heat is trapped in the small spaces created by the insulation, providing a buffer between you and cold weather.
Down comes from the plumage of geese and ducks—the fluffy layer underneath the feathers. Down is incredibly lightweight and incredibly effective at trapping air, giving it a warmth-to-weight ratio that is second to none. When the weather is cold and dry, down is the warmest and lightest insulation in the world. Period.
The Achilles heel of down is wet weather. When down gets wet it loses its loft and its ability to insulate. And once it’s soaked, it takes a long time to dry. Even high humidity can limit the effectiveness of down. Water-resistant down (see below) was created to mitigate this weakness.
What is Fill-Value?
When looking at down jackets, you’ll often notice a fill-value such as 450-fill, 600-fill, or 800-fill. Fill-value is used to rate the quality of the down used in the jacket, and is measured by how many cubic inches one ounce of the down can fill. Higher fill-values mean higher quality, which translates to more loft and warmth.
Synthetic insulation is usually made from polyester that is spun into filaments to mimic the consistency of down. While not as warm as down, synthetic insulation can still be very effective at trapping air and providing warmth.
Unlike down, synthetic fill will continue to insulate even if it gets wet, making it a great choice in wet or humid conditions. Plus, Synthetic insulated jackets are often less expensive than down.
Water-resistant down, aka treated-down, is down insulation that has been treated with a hydrophobic (meaning water-resistant) coating at the molecular level. If you’re dealing with wet, humid conditions, and are unwilling to go without the superior loft and warmth of down, water-resistant down is a great option. Manufacturers have a number of different proprietary names for it, such as DriDown, Q.Shield Down, DownTek, Hydrophobic Down, and the list goes on.
To harness the respective benefits of both down and synthetic insulation, some manufactures are creating hybrid jackets that strategically use both. In such jackets, synthetic insulation is used in areas most likely to get wet, like the shoulders, collar, and hem, while down insulation is placed around the core to deliver maximum warmth.
Staying warm when it’s cold outside is one thing, but add wet weather to the mix and staying dry becomes equally important. Read on to learn how to choose a jacket that will shrug off the storms.
For maximum protection in wet weather, you’ll want a jacket with a waterproof/breathable membrane. Fabrics engineered with a waterproof/breathable membrane are completely impervious to liquid water, but still allow water vapor to pass through, allowing the fabric to breath when you start to work up a sweat. Gore-Tex is the industry gold standard for waterproof/breathable fabric technologies, but there are now a number of similar products that offer a comparable level of performance.
The majority of outerwear is finished with a DWR (Durable Water-Repellent) treatment. DWR treatments are a polymer applied to face fabric that creates microscopic ‘pegs’ or ‘spikes.’ These pegs cause water droplets to bead and roll off the jacket, instead of spreading out and soaking through. So when you see water beading up on the jacket, you can thank the DWR.
Unlike waterproof/breathable membranes that are completely waterproof, there is a limit to the effectiveness of DWR. As a general rule, count on it to keep you dry in light rain and snow. Dirt, grease, smoke, bug spray, etc, can also clog and flatten the DWR pegs, limiting its effectiveness over time. Washing and drying the jacket will restore the DWR, and there are number of products that allow you to reapply a DWR treatment on your own.
When shopping for a jacket, you’ll often see a waterproof rating listed in the thousands with millimeters, such as 10,000mm or 20,000mm—sometimes abbreviated as 10K, 15K, 20K, and so on. This rating comes from what’s known as the “static column test.” In this test a one-inch diameter tube is placed vertically over a piece of fabric. Water is added to the tube until the fabric begins to leak, that amount of water is then measured in millimeters, as in “this piece of fabric withstood 20,000 millimeters of water pressure before leaking.” As a general rule, though, fabrics rated 5K or more are rainproof, 10K or more are generally waterproof, and a rating of 20K or more is going to keep you dry in the nastiest weather imaginable.