Fast fix: Not required.
Home remedy: “Rust is a hard stain to get out, because it has tiny particles that get stuck in the fiber,” says Martin Wolf, the director of product and environmental technology for Seventh Generation, a manufacturer of eco-friendly cleaning agents. For best results, treat with a commercial rust remover that’s safe for fabrics, such as Rx for Spotting Rust Remover (chemspecworld.com for store locations). Then launder as usual. If you don’t have a special rust-removal product, Wolf recommends pretreating the stain with a product containing surfactants (lubricating agents found in most detergents), then laundering. No matter what: Don’t add chlorine bleach to the mix. It reacts with the rust, intensifying the discoloration.