When rust bloom or burnt-on carbon will not shift, a soft sponge only polishes the problem. This emery (carborundum) brush uses a grit near diamond hardness to grind through rust, baked carbon, and hard-water scale on cast iron, bare stainless, grill grates, oven racks, and burner caps.Because the grit is aggressive, keep it off nonstick coatings, polished glass, and soft decorative finishes. Wet the surface, scrub the stain, rinse residue, then season cast iron again if you took it back to bare metal. Store dry with the black handled brush ready for the next stubborn job.