Before applying the oven cleaner, place a pot of boiling water on the oven's lowest rack and close the door for 15 minutes. The hot steam will help loosen the baked-on spills so the oven cleaner works quickly and effectively. Apply the cleaner and wait the recommended amount of time for it to clean effectively, then wear gloves to scrub or wipe the cleaner, grime, and grease with a cloth or sponge.