A comfortable bed is a clean bed!
Not Storing Your Comforter Properly.
1. Using a cotton bag for your duvet is ideal. Down feathers in particular need airflow during storage; so do not store them in plastic. However, for a duvet made from synthetic materials a plastic bag is acceptable.
2. Fold your duvet while pressing it flat to reduce its volume. Place the folded duvet in your bag and seal it tight. Ideally, your storage bag should have a drawstring or zipper to close the top, but this is not necessary.
3. Make sure to store your duvet cover in a dry location. Mildew can be detrimental to your down comforter.