The baker's percentage system anchors any sourdough recipe: flour equals 100 percent, and every other ingredient is expressed as a percentage of flour weight. To scale a recipe, simply pick a total flour weight and multiply by each ingredient's percentage — for example, with 800 grams of flour, 75 percent hydration equals 600 grams of water, 2 percent salt equals 16 grams, and 20 percent levain equals 160 grams. The levain-to-flour ratio in the dough is the inoculation rate; Tartine's formula uses a strong 20 percent levain, while other approaches range from 10 percent for slower, more flavorful ferments to 25 percent or more for faster, less sour ones. A higher inoculation rate produces faster bulk fermentation, more open crumb, and less sour flavor, while a lower rate produces longer bulk with deeper, more tangy flavor.
Autolyse comes first: mix only flour and water — no salt, no starter — and rest for 30 minutes to 2 hours. This period hydrates the flour and develops gluten passively, improving extensibility before any fermentation begins. A warm autolyse at room temperature (30–90 minutes) emphasizes enzymatic activity, while a cold autolyse in the fridge (8–24 hours) pushes even more flavor development and extensibility at the cost of slower gluten formation. After autolyse, salt and ripe levain are mixed in, and the dough enters bulk fermentation. During this first rise, most of the dough's flavor and structure develop over 4–8 hours at 24–26°C, ending when the dough shows visible jiggle, a domed top, and roughly 50–70 percent rise. The signature Tartine method runs through autolyse, mix, and a 4–5 hour bulk punctuated by sets of folds. A foundational recipe of 1,000 g bread flour, 750 g water (75 percent), 200 g ripe starter (20 percent), and 20 g salt (2 percent) illustrates the approach.
Dough temperature, often called DDT, is calculated as a weighted sum of flour, water, starter, and ambient temperatures plus a friction factor from mixing, with 26–28°C being the standard baker's target. In winter, warmer water at 30–35°C and a warmed bowl can compensate; in summer, chilled water or cold starter keeps the dough from over-heating. Levain building is its own craft: a levain is a sub-portion of starter freshly built up for one bake, distinct from the mother starter you maintain, while the term "preferment" refers to any portion fermented before final mix including poolish and biga, which use commercial yeast. A single build uses one feeding and is fine when the starter is active; a double build uses two successive feedings and is preferred when the starter is sluggish or fridge-cold. For same-day baking, build the levain 4–6 hours before mix using a 1:5:5 ratio at 24°C so it peaks right when it is needed. Liquid levains at 80–100 percent hydration rise faster with milder lactic-acid flavor, while stiff levains at 50–60 percent hydration rise slower and produce more acetic acid for a sharper tang.
Folds replace hand kneading throughout bulk. Stretch and folds every 30 minutes during the first 2–3 hours strengthen gluten and lightly degas the dough; coil folds, where the dough is lifted from underneath and folds on itself, are gentler and favored for high-hydration doughs; lamination stretches the dough thin on the counter and folds it back up, distributing inclusions like seeds or cheese while aligning gluten. The windowpane test confirms gluten development — stretch a small piece thin, and if light passes through without tearing, gluten is sufficiently developed. "Al dente" gluten tears slightly at the windowpane stage; "fully developed" gluten is very extensible with no tearing, and that full development is what produces open crumb. Dough strength is gluten's ability to hold gas and shape: strong dough feels elastic and holds form, weak dough spreads and tears. Fermentation tolerance is the workable window from end of mix to collapse; a wider tolerance gives more schedule flexibility. To build tolerance, lower inoculation to 10–12 percent, cool the dough to 22–24°C, or pre-shape and refrigerate bulk.