Porcelain dishes can quickly become stained or unsightly if the finish is crazed or full of tiny cracks. These cracks absorb liquids and grease, which sometimes results in brown stains that seem to get worse over time. A paste made of hydrogen peroxide and cream of tartar may remove the stains.
Cover a work area with newspaper or an old plastic tablecloth. Set the affected dishes atop the work surface; then put on rubber gloves.
Pour a small mound of cream of tartar into a shallow bowl. Add just enough hydrogen peroxide to make a paste. Stir it a bit with a toothbrush to mix the items and to load the toothbrush.
Brush the paste over the crazed areas on each dish, working the paste into the cracks with the toothbrush. Allow the paste to soak in for a while as you work from one area or one dish to another.
Wipe the paste off the dishes with a damp sponge after 30 minutes to determine if the stains are gone. If not, apply more paste and wait another 30 minutes. Rinse the paste away with tap water and a damp sponge. Wash the dishes with dish soap, if desired. Allow them to air dry completely.