Unzip your sleeping bag to allow air to circulate inside and deodorize the fabric. Lay your sleeping bag in a sunny location for three to five hours to kill mildew spores still living on the fibers.
Mix 1/4 cup each of table salt and lemon juice to create a paste. Spread the lemon and salt paste on mildew stains and allow the paste to dry in the sun.
Brush the lemon paste off with a dry cloth. Wet an old toothbrush and place two or three drops of laundry detergent on the brush. Scrub remaining mold stains to remove them.
Rinse the sleeping bag fabric by blotting it with a damp cloth. Let the sleeping bag dry completely.
Moisten two cotton balls with one to two drops of vanilla extract each. Place one cotton ball inside the foot of the sleeping bag and the other one inside the center area. Leave the cotton balls inside the sleeping bag for a minimum of three hours to deodorize any remaining mold smell.