Gas ranges use cast iron grates over the hob burners, which you place your saucepans on when cooking. Whether they are porcelain-coated or not, cast iron grates heat evenly. Just like any other part, you should clean the cast iron grates on a gas range regularly -- ideally, at least once a week, and as soon as is safe after spilling food on them. Although you can use a soap-filled steel wool pad on cast iron grates, avoid doing so for porcelain-coated grates.
Allow the cast iron grates to cool completely before washing. The cast iron retains heat, and washing them while they are still hot can cause cracks and damage to the grates. Fill the kitchen sink with warm soapy water using washing-up liquid while you wait for the grates to cool.
Place the grates in the warm soapy water and allow them to soak for 15 minutes. If your cast iron grates are not porcelain-coated, the soak time is minimal; this ensures little chance of rust once you dry them.
Scrub the grates with a nylon scrubbing pad to remove lightly baked-on foods and grease. If necessary, add a little washing-up liquid to the scrubbing pad for extra cleaning power.
Rinse the grates well in warm water. Dry them completely with a hand towel. If you have grates that are not porcelain-coated, apply a small dab of vegetable oil on a paper towel and rub the oil into the grate surface. Wipe off any excess oil with a dry paper towel.
Lay out newspaper on a flat surface. Put on a pair of rubber gloves and place the grates on top of the newspaper.
Spray the grates with oven cleaner and place them in individual food storage bags for several hours -- or even overnight.
Take the grates out of the bags and wash them in warm soapy water with a nylon scrubbing pad. Rinse the grates well, removing all the oven cleaner, and dry them thoroughly. Apply a light coat of vegetable oil to the grates if they are not porcelain-coated.