Karl Sluka feathers and down come exclusively from geese and ducks, i.e. water fowl. Nature has provided geese and ducks with a unique protection against heat loss, their plumage, in order to withstand adverse weather conditions: This plumage, by the way, consists of a horn-like substance like our hair. When it comes to plumage, one distinguishes between down and feathers.
A down is three dimensional. From a punctiform core, delicate branches storing air appear to spread out in rays. Air is a poor conductor of heat and thus a barrier to heat loss. Especially large down have a greater storage capacity. They can store more air and thus insulate better. A down weighs about 0.001 – 0.002 grams. Therefore, when you are sleeping under a down comforter you are being kept snug and warm by app. 1 million down.
What’s more, they are hygroscopic, i.e. they take up moisture and release it again to the environment in combination with a suitable shell. One speaks of moisture absorption, creating an ideal microclimate in bed.