Stainless steel sinks stain quickly, especially because of limestone in the water and some acidic foods. Fortunately, stains on stainless steel sink can be removed with the proper ingredients.
Wash the sink with mouthwash. It contains substances that remove stains and disinfects the sink.
Rub the sink with toothpaste. Like jewelry, stainless steel stains can be removed by using toothpaste. Remove any trace of water from the sink (it must be perfectly dry), apply a little toothpaste (white) and rub using an abrasive pad. After 10 minutes remove the toothpaste with water.
Lemon juice. Squeeze a lemon and sprinkle the resulting juice all over the sink and then rub with a sponge. Rinse after a few minutes.
For extra shine, add a little olive oil (or sunflower oil) on a dry cloth and rub the sink with it. The resulting gloss will be amazing. In addition, the stains will disappear like magic.