A down comforter can be washed in the washing machine, but it takes extra care and drying time. It can take several hours to complete the laundering process for a down comforter.
A large-capacity washing machine is the only special requirement for washing a down comforter. Only use about half the regular amount of detergent.
Step 1: Laundering
Wash the comforter in the washing machine set on the delicate cycle. Run the rinse cycle a second time if a soap smell remains.
Step 2: Drying
Toss three or four tennis balls or some rolled up socks in the dryer along with the comforter, and set the dryer to run on low heat. Check the dryer often; if the tennis balls overheat, remove them and hand-fluff the comforter.