Your carpet may seem like an unlikely place for a rust stain to appear, but rust can develop on any metal surface, including furniture or toys, and quickly transfer to your carpet. Rust is a type of organic stain that spreads and transfers easily. While many commercial products exist and are recommended for rust stain removal, you can avoid the extra expense and chemical exposure while removing the rust stain from your carpet using products from your home.
Scrape any stuck-on rust off your carpet using the dull side of a table knife. Remove the rust substance carefully, making sure not to snag your carpet. Vacuum up the rust particles when you're through.
Pour 1 tbsp cream of tartar into a bowl. Add enough water to make a thick paste, the consistency of creamy peanut butter. Work the paste into the rust stain on your carpet using your fingers, then let the paste sit on your carpet for 30 minutes.
Dampen a clean cloth with cool water. Blot at the rust stain from the exterior, working in toward the middle, to remove the cream of tartar paste and rust stain.
Pour white vinegar over the site of the remaining rust stain on your carpet. Use enough vinegar to wet the stain, but not saturate it, then allow the vinegar to dry on the carpet. Vinegar is a natural rust remover.
Vacuum your carpet to remove the dried vinegar and rust stain remnants.
Lemon juice is a natural rust remover. Test for colour fastness before using on your carpet.
Commercial rust stain removers contain chemicals that can be dangerous to children or pets. Use with caution and keep pets and children away until the chemicals are fully removed from your carpet.