A baking stone is a thick surface that stores heat when preheated and suddenly transfers that heat to the dough from below. A thin home-oven sheet pan cannot do this; it cools as soon as the dough is placed on it, so there is no strong upward push from below. The stone noticeably increases the dough’s rise in the first few minutes and makes the bottom crisp.
The most critical moment for bread in the oven is the first few minutes: the gas inside the dough heats up and expands, and the bread suddenly gains volume. This rise requires strong, steady heat from below. A thin sheet pan stores little heat, so when the dough is placed on it, the pan loses its heat and that push never happens. A thick stone or steel plate, by contrast, quickly transfers the heat it has stored to the dough; the bread rises and its bottom browns early.
The stone only works if it is preheated. Place it in the oven before turning the oven on so it heats along with the oven. When the oven indicates that it has reached its set temperature, the stone is not hot enough yet; depending on its thickness, it needs an additional 30 minutes to 1 hour. If this time is shortened, the stone offers no advantage and may be no different from a thin sheet pan. Always put the stone into a cold oven and let it cool along with the oven. Thickness also matters: a thin stone heats quickly, but gives up its stored heat just as quickly and may not be enough for a second loaf.
Kitchens without a baking stone have a few options. A thick steel plate does the same job, or even faster. An upside-down, thick sheet pan is a partial solution. Unglazed clay tiles can also be used, but they must be food-safe and unglazed. The most common home solution is baking in a lidded Dutch oven; it provides heat from below and traps steam inside, doing much of the same work as the stone.
Place the dough directly on the stone. Use a peel lined with paper or an upside-down sheet pan, then slide the dough onto the stone with the paper. The paper can be pulled out halfway through baking if desired. Do not sprinkle flour on the stone because it will burn and smell bitter; paper avoids this problem entirely. Close the oven door quickly, because every second it stays open lets the heat stored in the stone and the steam inside escape. If you do not have a peel, an upside-down cutting board also works, as long as its surface is flat and dry enough that the paper will not slide.
The stone needs little care, but the rules are strict. Do not wash it; soapy water gets into its pores and cannot be removed. Scrape off oil and dough residue after the stone cools; dark stains that develop over time are not defects. The stone cannot withstand sudden temperature changes: do not put anything cold on a hot stone or place a hot stone on a wet counter, both of which can cause the stone to crack. A properly used stone lasts for years. It can be left in the oven; while it is there, it also helps even out the oven’s heat and reduce temperature fluctuations.