To provide warmth, a down jacket or sleeping bag needs to be light and airy. Sometimes down can lose its loft and become lumpy. In order to restore its warmth, try the following methods.
Make sure the item is completely dry. If it's wet, lay it flat where it can dry completely. This alone may be sufficient to restore the down's loft.
If the lumps remain, place the item in a clothes dryer along with three clean tennis balls.
Turn the heat to the lowest setting. Set the timer for 20 minutes.
Remove the item from the dryer. The loft should be fully restored.
Down should be stored in a closet with breathing room--jackets on a wide coat hanger, and sleeping bags in a large mesh storage bag--not compressed in a trunk, drawer or stuff sack.
- Store your down sleeping bag in a loose sack that doesn't compress the down. Small stuff sacks are suitable only for short storage periods.