If you often wash aluminium or other metal pots, pans, dishware and utensils in your porcelain sink, you're bound to get scratches in the sink at some point. Although porcelain is a strong, durable substance, when metal brushes against it, the irritation takes off some of the sink's porcelain glaze. Repairing a porcelain sink is more a matter of having the correct supplies than anything else. The time and effort it takes to repair the sink is minimal.
Plug the sink with a drain plug, and fill the sink with enough water to cover its inside bottom surface.
Dampen a pumice stone in the water. Make sure it's completely drenched.
Work on scratches on the top and interior sides of the sink. Buff the length of the scratch in a back and forth motion until the scratch is removed.
Remove the drain plug from the porcelain sink, and drain the water from the sink.
Buff the scratches from the interior bottom surface of the sink with the pumice stone in the same fashion you removed the scratches in Step 3.
Keep the pumice stone wet at all times when you're working on the scratches. If it gets dry, it becomes hard and can cause scratches to the sink. You can purchase pumice stones from most department stores, hardware stores and drugstores. Purchase several at a time because they wear down fast when you're using them on a porcelain surface. If you don't have a pumice stone readily available, use baking soda to remove the scratches from the sink. Sprinkle the baking soda on the length of the scratch, then buff the sink with a soft cloth.