No preheating. Just place food on Stoneware and cook. (Dense frozen foods like meat should be thawed first. Absorbs and retains heat for even baking and golden crusts. Draws moisture away from food so it cooks light and crispy. Virtually nonporous, so it does not retain oils, odors or flavors. Nonstick seasoning builds up with every use: the darker it looks, the better it cooks. Some surface imperfections from use, as seen in pics, but will not affect use. In excellent used condition. ***STONEWARE CAN NOT BE BUNDLED***