When cleaning a Q grill, is it possible to damage/remove the porcelain enamel? I just purchased a used Q2200. I wouldn't be surprised if the interior has never been cleaned. The firebox and lid were simple enough, but the grates are taking me forever. I'm soaking the grates in hot water with Dawn soap. A wire brush is only useful after I've scraped, but scraping is tedious and time consuming. On the underside of the grates around the perimeter, there is a dark film-like substance that seem to come off more like a thin layer of paint than the baked-on carbon buildup on the rest of the grates. Underneath is dark gray like everywhere else on the grill, but I'm wondering if this is the porcelain enamel? Is the enamel on the underside only?