Stainless steel is fairly durable, but certain substances can cause it to become discoloured or stained, despite its name. Acidic substances can stain stainless steel, but fortunately there are things you can do to remove these stains. Most of the things you need to remove stains from stainless steel are probably already in your cupboard. Grab a scouring pad and some baking soda and in no time at all your sink will shine like it is brand new.
Rinse the sink to remove any leftover acidic liquid. Fill your sink with water until the stain is covered. Add baking soda or ammonia. For baking soda add 1/4 cup for every 1 qt of water. For ammonia, add 1/2 cup per every gallon of water. Ammonia creates irritating vapours, so it should be used in a well-ventilated room and with gloves for skin protection.
Allow the cleaner to soak in the sink for 15 to 20 minutes. Drain the sink and rinse it thoroughly.
Moisten a sponge with clean, warm water. Add a few drops of liquid dish soap to the sponge.
Scrub the sink with the soapy sponge thoroughly. Rinse the sink free of soap. Dry the sink of excess water with a clean, soft cloth.