To clean a down comforter, let it air out in bright sunlight on a windy day, three to four times per year. Every seven to 10 years, take your comforter to the dry cleaner for a thorough cleaning. Real down feathers, like those farmed from Pyrenees geese, lose their loft when washed in a washing machine.
Check the manufacturer's label before attempting to wash any down comforter at home. Certain brands of Pyrenees down comforters, such as Pinzon, use a patented PermaBaffle technology to allow owners to wash their comforter in a standard washer, and dry in a dryer. If you are able to use a dryer, place a sneaker in the dryer with the comforter to make sure the down fluffs back up again. However you dry your down comforter, make sure it is completely dry before using to prevent mildew.
Spot-clean your down comforter when necessary using a mild liquid detergent. Protect the comforter with a duvet cover to keep the fabric from being broken down by the oils in your skin, and turning it brittle. Use a flat sheet to provide further protection, and allow you to only wash the duvet cover once per week.
Pyrenees down comforters are manufactured using the down of geese from the Pyrenees mountains between France and Spain. In addition to comforters, the down is used by manufacturers to make blankets and pillows.