Porous catalytic coating absorbs fat and vapour from cooking. It self cleans by turning the fat to ash. Simply wipe the ash away with a damp cloth. The lining can be cleaned by wiping with hot soapy water. They have a fixed life span and may discolour with age and eventually need to be replaced. The linings can be removed and cleaned by wiping with hot soapy water, please do not use any oven cleaners to wash the catalytic linings.