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Fill power is a measure of the loft or "fluffiness" of a down product that is loosely related to the insulating value of the down. The higher the fill power the more air an ounce of the down can trap, and thus the more insulating ability an ounce of the down will have. Fill power ranges from about 300 (in³/oz or 175 cm³/g or Lorch 75 mm/30g) for feathers to around 900 (in³/oz or 520 cm³/g or Lorch 225 mm/30g) for the highest quality down. Higher fill powers are associated with a larger percentage of down clusters and a larger average down cluster size. ==Measurement== Fill power is the most frequently used measure of down quality. It involves measurements taken of a one-ounce sample of down in a plexiglas cylinder with a weighted piston compressing the down. The test requires controlled temperature, humidity, and preparation of the sample. All other things being equal a parka (duvet or sleeping bag) made with high fill power is lighter and more compressible than an equally warm one made with lower quality down. Fill power is expressed as cubic inches per ounce (in³/oz)—a lofting power of 400–450 is considered medium quality, 500-550 is considered good, 550–750 is considered very good, and 750+ is considered excellent. US 2000 norm: cylinder diameter: 241 mm conditioning: steaming +3 to 5 days in a screen box compression cylinder: non-mechanized cylinder of 68,3 grams. Mass of the sample: 1 oz = 28,4 grams. EN norm: cylinder diameter: 284mm, conditioning: tumble dry +2–5 days in a screen box compression cylinder: Lorch machine = mechanized cylinder weighing 94,25 grams, Mass of the sample:30 grams 750+ fill is quite different from 400 fills. Almost all down commercially available is a secondary product of geese raised for consumption. It would be prohibitively expensive to raise geese for down alone. The geese that are the source for lower fill down are about four months old when they are "harvested" for food. Down from these geese can be carefully sorted, washed, and blended, but it will never loft like really mature down. The 700+ down fill comes from a small number of birds kept for breeding purposes throughout the year. These geese molt naturally in the spring. While their down is loose it is collected by hand. It is very rare and, of course, expensive. The larger individual plumules are what gives the greater loft. The only way to get down of this quality is by careful hand selection which is the major factor in its scarcity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fill power」の詳細全文を読む スポンサード リンク
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