I prefer my bottom crust to be as thick and dark as possible, but if you are using a non-enameled cast-iron pot, you will need to tip the loaf out of the Dutch oven after about 25 minutes of baking time to prevent the bottom from burning before the loaf is done. This must be done carefully to avoid burning yourself. Finish baking directly on the middle rack for an additional 12 to 20 minutes.