Wait for the porcelain grates to cool down before cleaning them.
Put the grates in the sink with warm, soapy water. Wash them well with a rag.
Rinse and dry the porcelain grates thoroughly before putting them back on the stove.
Let the grates soak for a few hours in warm, soapy water if they are heavily soiled. Scrub with a fine steel wool pad to remove the grime. Rinse and dry the grates well.
Lay ammonia-soaked paper towels over any cooked-on spills that are still on the grates. Wait 40 minutes. Rinse the grates with a damp rag, then scrub them with a fine steel wool pad. Wash them with warm, soapy water, and rinse and dry the grates thoroughly.