Keeping stainless steel clean is not difficult if you wash items thoroughly each time you use them. After some time however, you may find stains on that allegedly “stainless” steel. And sometimes they are permanent. Here's how to know if the stains can be removed from your stainless steel utensils: Stains that look like rainbows on the surface of your utensil are permanent. Brown stains are easily removable by soaking a cloth in ammonia and placing it on the stain for a minimum of 30 minutes. Give it a normal wash afterwards.