Everyone who has ever taken a quilt out of storage knows that icky musty smell quilts can develop. Some of the smell comes from storing them in a dresser or trunk where the quilt picks up the stink of wood, glue, and paper linings often found in these items. If the quilt has been stored in the basement, it may have picked up the smell of mildew. If the quilt was kept in a plastic bin, the plastic off-gases will leech into the fabric. In addition, if your quilt is an old quilt with a wool batting, it will smell like sheep.
The best solution to freshening up smelly quilts lies right outside your door–fresh air, grass, and sunshine. Hang your quilt outside on a clothes line and leave it there for the day. If you don’t have a clothes line (how many of us do?) you can drape it across several lawn chairs. Bring it in in the evening. You may need to repeat the process for several days if the smell is very strong.
You can also use grass to help remove odor. The chlorophyll in grass is capable of neutralizing really strong odors. Lay a sheet on the grass and spread you quilt on it. If the quilt is not an antique, laying it in the sun will help the process. Turn the quilt halfway through the day so both sides get some good sun.
The last option is hard to believe but — vinegar. Fill a spray bottle with white vinegar and give the whole quilt a good spritz. Allow it to dry in the sun, turn the quilt over and repeat. Be sure to test your fabrics for colorfastness before getting any quilt wet.