Porcelain is a durable material commonly used for kitchen and bathroom sinks. While it stands up well to daily wear and tear, porcelain can sometimes develop stains. When metal silverware or cooking implements scrape across the sink during daily use, porcelain can become marked. These blackish-grey marks occasionally wash away with warm water and mild soap, but more often they require deeper cleaning to remove. You do not need to break out any harsh cleaning supplies, however, because some of those cleaning products can harm the porcelain itself. Simple ingredients can do the job more effectively and less expensively.
Mix 1 cup borax and 1/4 cup lemon juice until they reach the consistency of a paste. If you have a larger sink and want to remove marks from the entire surface, double the measurements to make a larger batch of cleaner.
Apply the borax and lemon juice directly to the metal marks on the sink and rub at the stains gently with a damp sponge. Be careful not to press too hard. Borax is mildly abrasive, and although the metal marks may seem to be embedded in the porcelain, they are really on the surface layer only.
Rinse the affected area of the sink with warm water.
Examine the sink to make sure the marks are completely removed. If not, repeat the borax and lemon juice paste until the marks are gone.
Dry your sink with a clean towel to avoid streaks.
If you have a coloured porcelain sink, test the borax and lemon juice in a hidden location to test for colour fastness.
Do not use steel wool or highly abrasive cleaners on your porcelain sink as these can scratch the surface.