Causes: Heat stains from oxidation are caused by stainless steel materials such as chromium, nickel, and steel, which undergo chemical reactions with oxygen in the air.

It happens when stainless steel is heated to a high temperature in the air. The oxidation layer is very thin and does not affect the function of the pot at all.

Workaround: Fill a pot with about two thirds of the water, add vinegar, lemon juice, citric acid and baking soda to boil together, then wipe off the stain.

Also, if you use vinegar to cook food in a pot, the rainbow color stain may disappear after cooking.

If you clean it with a stainless steel-only polish, you can manage it more cleanly.