Whether it is going outside in the elements or being snug and cozy in bed at night, you want to know what is the very best insulator you can get and maybe know it is coming from an ethical source.
You probably grew up with wool blankets or a polyester comforter, possibly even a silk blanket or cotton blanket. There again you might have been one of the fortunate who grew up with a down comforter or if you are of a certain age, an “Eiderdown”, known in the UK to be a comforter which over the years could have been filled with feathers, horsehair and maybe a blend of feathers and down. Given it was so thick and only sat on top of the bed (in equal parts for decoration and warmth), it was likely not all down.
Down is simply nature’s best insulator. Down is not the same as feathers. Feathers are for flying, they have a bony quill down the center. Down is the fluffy part needed for insulation usually on the breast of the bird. Down is many more times the price of feathers. Its quality is measured by the size of the down cluster (fill power) and the number of whole down clusters per ounce. (To be called all down 10% of “fly”, pieces of a down cluster, or the tiniest of feathers is allowed. These extremely tiny feathers cannot be separated out during the cleaning process as they are too small).
Nothing compares to down, not wool or polyester and definitely not cotton, (this would be more for just summer). However all down is not created equal. The most prized and rare down is Eiderdown. It has very powerful thermal properties and is super light and soft. It is gathered from the birds’ nest after it is no longer needed. Eiderdown ducks live in Iceland, Norway and parts of northern Canada.
Goose or duck down is more abundant in the world coming from countries as a by product as geese and ducks are part of the cultural diet. Goose down is usually loftier than duck down and comes mainly from Europe. Due to colder climates and coming from more mature birds the down clusters are large (anything 650 to 850 fill power is considered luxury quality), and therefore traps more body heat to keep you warm. Duck down comes predominantly from China, from younger birds with much smaller down clusters. The fill power is commonly 550.
If you are concerned about where your down is from and if is it ethically sourced, there is a new standard that you can read about at RDS.org.