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If you wash a goose down comforter at home, you must dry the goose down comforter with gentle heat in the clothes dryer. To expose damp areas, remove and adjust the down comforter several times during the drying cycle. Then return the goose down comforter to the dryer for another cycle. Finally, hang a goose down comforter out to air dry for at least 24 hours to make sure all sections are dry before replacing the goose down comforter on your bed.
As far as I know, comforters have to be drying cleaned only, otherwise you risk making it smaller than the bed.
TIP ADD ON: buy some cheap tennis balls (4-6 should work) and place them in dryer w/ down comforter, it helps the down, so it doesn't get all clumpy.
I would not dry my down bedding on any heat setting. Tumble dry or cool air only as heat will break down the natural oils in the feathers and down.
As advised in the tip making sure the down is dry through out the bedding is extremely important.