After bulk, the dough is divided and pre-shaped into rough rounds, then given a 20–30 minute bench rest covered so the gluten can relax before final shaping. Shaping aims for taut surface tension without ripping the dough — too gentle leaves a slack loaf that sags flat, too rough tears gluten and leads to a dense crumb. Slack dough that simply will not hold its shape after shaping usually traces to under-developed gluten, a warm environment, over-hydration, weak flour, or excess fermentation; a 20-minute rest followed by coil folds can often rescue it.
The shaped dough then enters final proof, traditionally in a banneton — a proofing basket lined with rice flour that supports the dough and leaves a spiral imprint. Bannetons are typically dusted with a 50/50 rice-and-AP blend or pure rice flour, with excess tapped out, and rice flour specifically is preferred because it does not absorb into the dough during long retards. Bench flour is the everyday flour used to prevent sticking during shaping, often all-purpose, while rice flour is reserved for bannetons so it doesn't incorporate into the dough. For very sticky doughs, a floured cloth liner inside the banneton prevents tearing and gives an even spiral pattern. Banneton sizing matters: 500 grams of flour dough typically needs a 20–22 cm banneton, and a tight banneton produces a taller loaf. Alternatives include a couche (linen cloth folded into ridges, dusted with flour, with batards resting seam-up between folds), a cane brotform, or even a colander lined with a floured tea towel.
Cold retard is where most of sourdough's signature flavor develops. Placing shaped dough in the fridge for 8–24 hours at 4°C slows yeast activity while letting bacteria produce more acid, which adds tang, makes the dough easier to score, and improves crumb. The sweet spot for maximum flavor is 12–18 hours; beyond 24–36 hours, gluten can over-relax and the dough becomes hard to score. Retarding for at least eight hours also helps the surface dry slightly so the ear will curl up cleanly during oven spring. Cold temperatures favor lactic acid (mild, milky tang), while warm bulk fermentation favors acetic acid (sharp, vinegary). For very long flavor development, the cold-shock method refrigerates shaped dough for 24–72 hours and bakes directly from the fridge without warming up, extending the retard window considerably. Bulk itself can be retarded overnight in the fridge for high-inoculation doughs or in warm kitchens where bulk would otherwise race too fast, slowing the yeast while still allowing slow flavor development.