Scoring directs where the dough opens during oven spring; without a score, it splits along its weakest point. The tool of choice is a lame — a razor blade holder with a curved or straight blade — the same tool sometimes called a scoring blade. Some pros snap a double-edge razor in half for ultra-clean cuts. Depth is roughly 5–10 mm at a 30–45° angle; shallow cuts produce little ear, overly deep cuts collapse. A single confident stroke along the long axis, just into the skin of the dough, gives the classic ear — the raised, crispy flap of crust along the score line. To get a bigger ear, the oven should be very hot, steam should be plentiful, the dough slightly under-proofed, the score deep and angled, and the blade very sharp. The "crown" is the ridge along the top of the ear from a deep angled score that lifts cleanly. A cross score, with two perpendicular cuts, opens a boule into four sections for decorative effect rather than maximum spring, while a double cut uses parallel lines to open the loaf wider, often used on batards. Over-scoring — too many cuts — opens the loaf in many places without producing a single defined ear, so one confident cut always beats five hesitant ones. For very wet dough that drags, dipping the lame in water or lightly spraying the dough's surface prevents tearing.
A Dutch oven is the most reliable tool for home sourdough baking because it traps steam released from the dough itself during the first 20 minutes of baking. Preheat the Dutch oven to 260°C, bake covered at 245°C for 20 minutes, then uncover and drop to 230°C for another 20–25 minutes. Parchment paper between the dough and the Dutch oven makes transferring quick and safe and prevents sticking. A baking steel transfers heat faster than a baking stone and yields better oven spring, while a stone gives more even radiant heat at lower cost. Without a Dutch oven, a baking stone plus a steam tray (lava rocks, a metal pan of hot water, or ice cubes) or a covered roaster all work. Baking on a tray without steam is possible if the loaf is sprayed with water before loading and a pan of boiling water sits on the rack below, though results vary. The initial oven temperature is sometimes called the firing temperature.
Steam phase management is critical: keeping the surface pliable for the first 15–20 minutes allows maximum oven spring, and then venting or removing the lid allows the surface to dry so the Maillard reaction (browning between amino acids and sugars at 140–160°C) and sugar caramelization above 160°C can produce color and flavor. Without sufficient steam, the crust becomes thick, leathery, and splits randomly. High heat combined with surface moisture can also create a rustic blistered crust, often in long-fermented, high-hydration doughs. Oven spring is the rapid expansion in the first ten minutes of bake from heat-released CO₂ and steam — the aim is a visible leap in volume. Internal temperature of 96–99°C, confirmed with a probe thermometer, signals doneness.
Standard loaf shapes include the boule (round, free-form, rising straight up from a round base — best oven spring and most forgiving of shaping errors, since round tension is more forgiving than oval), the batard (oval, slightly elongated, scored diagonally, requires tighter shaping or it flattens during proof), the bloomer (oval like a rolling pin, ideal for slicing for sandwiches and toast), and the pan loaf (baked in a loaf pan for easier shaping and even crumb at the cost of a thinner crust and a less dramatic ear). A tin loaf is an open-top Pullman-style pan that yields a square-sided loaf, while a pan loaf has one open side and produces tall sandwich slices with a side crust. To bake in a loaf pan, grease the pan, place shaped dough, proof until just above the rim, cover with foil for 20 minutes, then uncover and bake for 20–25 minutes at 200–220°C.