Cleaning grates are easy. Fill a basin with water and a dishwashing detergent. Soak grates in solution. You can scrub them with a nylon brush if necessary. NEVER use scouring powder such as Comet or steel wool. NEVER place grates, burners or burner caps in the dishwasher as the harsh chemicals will discolor the metal. Once clean, dry them thoroughly. You may need to wipe the cast iron parts with a light coating of vegetable oil to ‘season’ them. The secret is not to let the grease get baked in. Over time, these parts will discolor due to heat, acids & enzymes in foods.