For cotton and polyester: Mix a solution of ½ cup liquid laundry detergent per one gallon of water in a plastic bucket. Soak garment for 30 minutes. Machine wash in warmest water safe for fabric. Air dry. If stain persists, apply a liquid rust remover according to package instructions. Rinse in a solution of three tablespoons baking soda per one quart of water. Machine wash again.
For washable silk and wool: Pre-treat stain with a gentle liquid laundry detergent, such as Ivory Snow. Let sit five minutes. Flush stain with cool water. If stain persists, take the garment to a dry cleaner.