slip grate into gallon size ziploc bag. Do not put any holes in bag. Pour 2-3 T. ammonia into bag. Seal bag & let sit for 12 hrs. Do this overnight. Take grate out of bag in kitchen sink. Rinse the grate thoroughly and scrubb with a nylon scrubber.
Pour and spread on a thick coat of baking soda.Next, pour about 1 tablespoon of peroxide in each ring. You want enough to wet the baking soda but not drench it.Let sit for 15 minutes. After 15 minutes, begin scrubbing away the grime.For tough areas, use a knife to loosen the grime.Spray with your All-Purpose cleaner and wipe clean and dry.