Rust stains are some of the ugliest and most difficult stains to remove. The sleek look of porcelain is easily marred when rust comes into the picture. Detracting from its overall clean and shiny appearance, rust usually finds its way onto porcelain through hard water or as a residual from metal objects placed nearby. While these stains are unsightly to look at and irritating to clean, it's not impossible. Rust stains require a little more effort to remove from porcelain, but the end result is more than worth it.
Mix ½ cup baking soda with ½ cup white vinegar in a large container or bucket. Make sure that you have plenty of room to make up for the caustic reaction that vinegar and baking soda have together. The combination of the two causes fizzing and bubbles that can make quite a mess.
Apply the paste to the stained area once the bubbles have gone down. Scoop the mixture up with a clean cloth, and cover the entire area so that none of the stain is exposed.
Allow the paste to sit on the stain for an hour.
Rinse the paste away with clean water.
Mix a second paste of cream of tartar and 3 percent hydrogen peroxide in equal parts. Be sure to make enough paste to cover the entire stain.
Apply the paste to the affected area with a clean cloth and allow it to sit on the area for an hour.
Rinse the paste away with clean water, and scrub the area with a soft, clean cloth to remove any residual stain.