Mix apple cider vinegar with coarse salt to achieve a grainy paste. Apply this concoction to the stain and leave it for about an hour. Afterwards, remove the residue and wipe the area with a damp cloth.
Lemon and Borax Mixture:
Combine lemon juice with two tablespoons of borax (remember to wear gloves and a mask for safety). This mixture can be highly effective against rust. Spread it over the stain, wait for about an hour, and then clean and dry the area thoroughly.