Maintaining SKK Series products 3, 5, 7, 9, and 11: In most cases, you will only need hot water, a soft rinse brush and some detergent. This is sufficient to keep everything hygienically clean. Then you should rub your cooking utensils briefly with some cooking oil. Remove very stubborn dirt with a little detergent and a soft nylon sponge or plastic scouring pad. Never ever use steel wool. This will damage your cookware and void your warranty. We recommend that you do not clean your hand cast cookware in the dishwasher, because the detergents used in modern appliances are becoming more and more abrasive, resulting in a drying out of the surface sealing during cleaning in the dishwasher. The thing same happens when rinsing plates with gold trim in a dishwasher. Over time, the surface seal may darken. This is a normal process, which does not affect the usability properties in any way. You should not attempt to remove this discoloration. Your SKK cast cookware is intended for cooking, and not for storing food. Therefore, it should be cleaned immediately after every use. Let's face it, SKK cookware represents a substantial investment. Treat it with care and it will last a lifetime.