Down  comes from the plumage found underneath the exterior feathers of waterfowl like ducks and geese. It consists of soft, fluffy, wispy filaments. The down helps keep the birds warm in freezing water and increases their buoyancy. Europeans began using down for clothing approximately 500 years ago. The down is a by-product of the food industry.

How It Works

Down insulates by trapping air providing an effective thermal barrier. Down is a superior insulator from synthetic insulation due to its lightweight, ease in compression, long lifespan, and breathability. It performs best in a cold, dry environment like ours, or in situations where weight reduction and space savings are top priorities.

It is noteworthy, however, that down’s insulation performance crashes if it gets wet. The down will clump and lose the loft necessary to provide insulation. Most outerwear companies are careful to treat the shell fabric of down pieces with a DWR finish, increasing the water repellency of the fabric. Depending on the care instructions of your down item, it’s recommended to put your product in the dryer with dryer balls or tennis balls to boost loftiness. Down blankets can be machine-washed and should be machine-dried with dryer balls for restoring insulating loft.

Down does have a pesky habit of trying to escape products through holes in the fabric, so most manufacturers will use fabric referred to as ‘down-proof’, meaning the fabric is woven tightly enough to prevent down poking out.

Fill Power

Fill power refers to the measure of down’s ability to loft and thus trap heat. It’s calculated by how many cubic inches one ounce of down can fill in a testing device. Premium goose down can reach over 900 fill power! The advantage of higher fill power down is that it requires less down to fill space and achieve a higher temperature rating, thus creating a lighter weight product. By contrast, duck down maxes out at 750-800 fill power. Goose down is used in highest-end products due to rising costs. Most manufacturers use duck down.