Bar Keepers Friend is a powdered cleaning product that can tackle even the most stubborn dirt and grease. Writer Alex Beggs calls the Bar Keepers Friend her “only friend,” but also notes that it has damaged several items in her kitchen, and these are surfaces that you should avoid too while using the cleaning agent.

To ensure the longevity of your kitchen items, never use Bar Keepers Friend on surfaces like marble, granite, plastic, nonstick pans, uncoated cast iron pans, wood, enamelware, and melamine. The substance is also toxic to humans, so remember to wear gloves while cleaning, as the oxalic acid in the product can harm your skin.

Additionally, inhaling the dry powder can be dangerous, so wetting the surface and then scrubbing with a pre-dampened cloth works best. The best surfaces to use it on are stainless steel, glass, porcelain, chrome, stovetops, and Instant Pots, among others, but just make sure not to let Bar Keepers Friend sit on a surface for too long.