Remove rust stains from carpet by scraping away the residue, blotting with dish soap on a sponge and allowing about 5 minutes for soaking before absorbing the stain with a disposable white towel. Treat stubborn stains with ammonia and water or lemon juice, salt and vinegar.
Upon finding rust spots on carpet, begin the removal process by moving the source of the stain. If a metal table leg is causing the problem, consider relocating the table or placing a new protective cap over the leg to prevent further staining.
Scraping away the excess rust with a blunt object, such as a butter knife, keeps the stain from spreading. When scraping the rust, keep an eye on the carpet fibers to prevent damage. Vacuum to remove the loosened rust particles.
Many rust stains are removable with the scraping, wetting and blotting process; however, depending on the amount of rust and the color of the carpet, further treatment is sometimes required. Avoid the use of chlorine bleach, which reacts with the iron in rust to cause a stain that is not removable. Ammonia helps dissolve the rust stain. Mix 1 tablespoon of ammonia in 2 cups of warm water to treat the stain and blot with a clean white towel.