When using a stone hearth oven and directly baking on the deck surface, oil, debris and fats drip and fall on the deck surface causing a carbon build up over time. Using the wire brush should help eliminate most of the carbon build up. If not, on our newer ovens, we implemented a clean cycle. What the clean cycle will do is heat the oven up to 750°F and maintain that temp for 3 hours and then shut off automatically. Once the clean cycle has been completed. using the wire brush again will remove the remaining carbon build up and the deck will look practically brand new.