Bar Keepers Friend Cooktop Cleaner contains no harsh chemicals or phosphates. The active ingredient is natural and organic citric acid. BKF stovetop cleanser is safe to use on most surfaces: stainless steel, copper, aluminum, bronze, glass, porcelain, ceramic and more. DO NOT USE ON: silver, gold, natural stone such as marble or granite, or on lacquered, painted or mirrored surfaces. Stainless steel appliances are often coated in a protective film that could be damaged by scouring powders and cleansers. Always read your appliance manufacturer's recommendations before cleaning. When cleaning any surface or item in your home with a scouring powder, spray cleaner or soft cleanser, test the product on a small, inconspicuous area first.