Hydration is the single most important numerical concept in sourdough — it is the weight of water expressed as a percentage of flour weight, so 75 percent hydration means 750 grams of water per 1,000 grams of flour. Beginners should target 65–72 percent hydration with bread flour, which is easier to handle while still allowing an open crumb. Advanced bakers pushing for very open, holey crumb often work at 75–85 percent hydration, but only with strong flour and a confident handling technique. Hydration must be raised by roughly 3–5 percent for every 10 percent of whole-wheat flour substituted, since whole grains absorb more water. Beginners seeking lighter crumb in whole-wheat doughs can sift out about 20 percent of the coarse bran and reincorporate the rest, reducing fiber intensity while preserving flavor.
Flour choice shapes everything about a loaf. Bread flour, with 12–14 percent protein, develops stronger gluten and holds high hydration better than all-purpose flour at 10–12 percent, which gives a tighter crumb. Whole rye and whole wheat carry more minerals and microbes, producing more lactic and acetic acid and therefore tangier bread, while white bread flour yields milder, sweeter flavors. High-extraction flour, milled between whole grain and white, retains around 70–85 percent of the bran for flavor and nutrition with better gluten performance than 100 percent whole wheat. For beginners chasing open crumb, a strong bread flour with at least 20 percent whole grain or high-extraction flour is a sweet spot. Italian Type 00 flour is finely milled and often around 11 percent protein, excellent for pizza but less suited to tall sourdough loaves. Spelt has weak gluten and a nutty flavor and is best used at 30 percent or less; rye is sticky with very high enzyme activity, used at 10–20 percent unless making 100 percent rye — its soluble fiber gels and traps gas, producing a more uniform but denser crumb with deep malty flavor. Vital wheat gluten concentrate can be added at 1–2 percent of flour weight to boost strength in whole-grain, weak-flour, or high-inclusion doughs.
Salt's role goes far beyond flavor: it tightens gluten, regulates fermentation, strengthens crust, and slows over-proofing. The standard amount is 1.8–2.2 percent of flour weight — roughly 2 percent as a default, leaning toward 1.8 percent in high-hydration doughs and up to 2.2 percent in tighter ones for flavor balance. Salt should be added after autolyse, once gluten has begun forming — usually 20–40 minutes into bulk — because adding too early inhibits gluten development while adding too late causes uneven mixing. Water also matters: hard water rich in calcium tightens gluten and may slow fermentation, soft water gives a more open crumb but can feel slack, and chlorinated tap water can weaken gluten and disrupt yeast, so letting it sit uncovered for 24 hours or using filtered water is a common fix. Optional additions include diastatic malt powder at 0.5–1 percent of flour weight for extra amylase activity and mild sweetness, and a small amount of sugar or honey to feed yeast in early fermentation for faster rise and softer crumb, useful for beginners though not essential in true sourdough.