Salt/baking soda acts as a mild abrasive to help scrape the rust off as it dissolves. Slice a potato in half, cover the cut section with dish soap, and sprinkle salt (or baking soda) onto the potato. Oxalic acid dissolves rust, and the For pieces of metal without detailing or relief work, you can use regular dish soap and a potato to scrub rust away. All potatoes contain oxalic acid, which is a key ingredient in many cleaning products. Remove Rust With Dish Soap and a Salted Potato Rinse off the lemon, salt, and rust residue, and dry thoroughly. Scrub the object with the lemon rind, or if the spots are stubborn, use steel wool or a wire brush. Let the salt and lemon mixture sit for about two hours. Cover the rusted areas with salt and then squeeze lemon juice over the layer of salt. This technique combines the acidity of the lemon with the abrasiveness of the salt to tackle small rust spots. Rinse the paste off with water and dry thoroughly. Use steel wool or a wire brush to scour the object and remove the rust.
Let the paste sit on the object for an hour or so. Mix water and baking soda into a thick paste and spread the paste all over the metal, making sure that rusty spots are well covered. It also works well on items made out of thin metal. Baking soda works well on items with light rust stains.