Qualities
Types of down
Down-filled sleeping bags are generally warmer and lighter than their synthetic counterparts. Down is considered the best insulation in cold, dry weather conditions and expedition use and comes in the following varieties:
- High loft goose down is made from very fine down and provides the best insulation over any other filling because it traps the most air. High loft down is mostly used in expedition sleeping bags and outerwear, where minimal bulk and low weight are critical.
- Goose down is very fine and more reasonably priced than high loft down.
- Duck down is less fine than goose down and considerably less expensive.
Fill power
- Down is rated according to fill power. This specifies the number of cubic inches one ounce of down will occupy. For example, if one ounce of down takes up a volume of 700 cubic inches, it is given a 700 fill power rating.
- Loft refers to the thickness of the insulating material in a sleeping bag or garment.
- The quality of the down is directly related to its fill power rating. In other words, down warmth is a function of both fill power and the amount of fill in a sleeping bag or garment.
- High quality down has a high fill power and is much loftier than down of a lower quality, requiring fewer ounces of down to create insulating warmth.
- Most companies use only goose down, which has a minimum fill power of 500 to 550.
- The higher the fill power, the better the down will insulate, because there is less of a chance of cold spots.
- Today's higher-end manufacturers offer 600 to 750 fill power down as their standard fill.
- If a label doesn't specify fill power, it is usually because the down falls in a range below 400 cubic inches or the item contains less than 75% down.
Down also comes in a number of different grades (or qualities). For example, a 90% goose down garment will consist of 90% down and 10% feathers. The higher the percentage, the purer the down. High percentage grade insulation will also be very low in weight and bulk, but higher in price.
