Hard water contains a high mineral content, which causes lime scale to form on porcelain sinks. Lime scale has a crusty white, discoloured appearance. Remove lime scale as soon as you notice it to prevent it from continuing to build on the porcelain surface, which will make it more difficult to remove later. You can remove lime scale from the sink with common items in your home. Regularly drying and wiping the sink down after every use will help to prevent lime scale from forming in the future.
Fill a small bowl with white distilled vinegar. Soak sheets of paper towels in the vinegar. Place the soaked paper towels over the areas of lime deposits. Press the paper towels down so that they lie flat on the porcelain sink. Wrap them around the faucet if it contains lime build-up. Allow the vinegar to soak for 1 to 2 hours. Wipe the porcelain sink with a damp washcloth to remove any remaining residue, and then rinse the sink with cool water.
Combine 3 parts of baking soda with 1 part of cool water in a bowl to create a paste if any lime deposits remain. Apply the paste to the faucet over the lime residue. Allow the paste to sit for 30 minutes to 1 hour. Wipe the baking soda paste off the sink. Rinse the sink with cool water to remove any lingering residue.
Purchase a commercial limescale removal product if the home remedies don't work. The chemicals will break down thick lime scale more efficiently than either vinegar or baking soda. Always follow the directions on the product to ensure that you use it properly.
Avoid allowing standing water to remain in the sink; this will result in hard-water deposits.
Never use abrasive cleaning products or supplies to clean porcelain sinks; they may scratch the surface.