Make a solution of mild soap and warm water in a plastic cleaning bucket. Use a clean, non-abrasive sponge.
Soak the cloth or sponge in the water. Wipe the sink thoroughly but carefully. Run clean water into the sink, and check to see whether the sink is clean. Repeat the cleaning if soiled places remain. Rub soap residue or other dirty spots with sponge soaked in the mild soap and water solution.
Clean stubborn soiled areas with plain soap, if necessary. Rub soap onto the areas with the sponge. Rinse with water and repeat as necessary.
Treat tough stains with a layer of mild toothpaste. Spread toothpaste onto a soft-bristled toothbrush. Run warm water over the stained places and scrub with the toothbrush. Rinse the toothpaste from the porcelain immediately after scrubbing and wipe with a clean cloth. Repeat if necessary.
Rinse the clean sink with warm water and wipe with a clean cloth to prevent water spots.