If your favorite tablecloth succumbs to mildew stains or odor, there's no need to discard it yet. In some cases, the stain and odor go away after treating the fabric with lemon juice or hydrogen peroxide. Washing the tablecloth afterward with vinegar or baking soda and laundry detergent cleans the entire tablecloth and removes musty odors.
Take the tablecloth outdoors and set it over a chair, table or banister so you can see all the mildewed areas. If the tablecloth is wet or damp, allow it to air dry for at least 30 minutes; otherwise, it may be difficult to remove the mildew.
Put on a dust mask and brush each mildew spot with a scrub brush. This eliminates some of the mildew spores that cause stains and musty odors. Examine the tablecloth completely to ensure you've brushed away as many spores as possible. Rinse the brush outdoors with a garden hose or by dumping a bucket of water over it, then allow it to dry outdoors.
Pour a little lemon juice over each mildew spot if there are only a few, then sprinkle salt over the lemon juice to act as a mild abrasive. Allow the lemon juice to sit for several minutes, then rub the affected areas gently with a damp sponge. Allow the tablecloth to air dry completely. The lemon juice, fresh air and sunshine may bleach the stains out.
Pour a small amount of hydrogen peroxide on a sponge if dark spots remain on the tablecloth. Dab the spots with the peroxide, then allow the tablecloth to air dry.
Wash the tablecloth in the washing machine using your favorite laundry detergent designed for delicates, using the hottest water recommended on the tablecloth's care tag. Add 1/4 cup white vinegar during the final rinse cycle to remove lingering mildew odors.
Remove the tablecloth from the washing machine and smell it. If it still has a musty odor, wash it again, adding 1 cup baking soda along with your favorite laundry detergent designed for delicates.
Dry the tablecloth over a clothesline in a nonhumid area, or in a dryer on a low-heat setting.