Down is one of nature's finest insulators. Nothing matches its warmth for weight, compressibility, and resilience. Its ability to absorb perspiration and cozily drape along the contours of your body are unparalleled by synthetic materials.
Down consists of thousands of plumules – tiny pods of light, fluffy filaments that line the underside of waterfowl feathers. Down is harvested from ducks and geese that are being prepared for sale as food. All down fills also contain some feathers and feather fibres.
MEC uses both duck and goose down in the construction of its down sleeping bag. The quality of down doesn't depend on the bird species it comes from, but on the bird's environment and maturity. Birds respond to colder, wetter conditions by growing fluffier, warmer down. White or grey down has the same performance. For purely cosmetic reasons white is more expensive than grey. It can be used in light weave or translucent fabrics without showing through.
Fill-power (or loft power) is a measure of fluffiness. It is expressed as the number of cubic inches an ounce of down displaces. Fill-power of 500 to 550 is mediocre, 600 to 700 good, and 750 to 850 excellent. Higher fill-power articles provide more warmth for the same weight.
Down is more expensive than other insulating materials. However, when you divide its cost by the number of cozy nights it provides, down is a bargain. A down bag costs approximately 50 percent more than a synthetic bag of the same temperature rating, but down insulation lasts about three to five times longer.
When it gets wet, down insulation is compromised. In damp conditions, a waterproof-breathable shell fabric can protect sleeping bags or jackets from external wetness. In cold climates, a vapour barrier sleeping bag liner keeps internal moisture out of the down fill. In consistently wet conditions, it can be very difficult to keep down dry, in these circumstances, a synthetic fill may be the best option.
Down sleeping bags and outerwear require maintenance to perform at an optimum level. For tips on airing, cleaning, and storing down items, read Down Sleeping Bag Care.