Hydration is expressed as water weight divided by flour weight, and it changes handling far more than it changes the finished loaf. A 70 percent dough and a 78 percent dough made from the same flour can produce similar crumb if both are fermented and shaped well. The difference shows up in the mixing bowl, not the oven. David Anthes, who bakes small batches in his home kitchen in Bend, Oregon, works mostly between 72 and 78 percent and treats hydration as a handling decision rather than a quality one.
Flour protein and milling determine what hydration a given dough can carry. Bread flour at 12.7 percent protein absorbs more water than all purpose flour at 10.5 percent, because more gluten forming protein means more sites to bind it. Whole grain flours absorb more still, since bran and germ hold water that white flour does not. A whole wheat blend at 80 percent hydration can feel drier than a white dough at 72 percent. Anthes adjusts water whenever he changes flour, and he adds the last 5 percent as a bassinage after the gluten network has already formed.
Higher hydration slows gluten development at the start. Water dilutes the protein concentration, so glutenin and gliadin chains take longer to find each other and form the linked network that traps gas. This is why a 78 percent dough feels like batter for the first hour and then transforms. Nothing was wrong. The network simply needed time and mechanical input. Anthes uses this window rather than fighting it, letting the dough rest before touching it.
Extensibility and elasticity move in opposite directions with hydration. Wetter dough is more extensible, meaning it stretches further before tearing, and less elastic, meaning it springs back less. That combination makes shaping harder because the dough will not hold the tension applied to it. Drier dough holds shape well but resists expansion in the oven and can produce a tighter crumb. The working range for most home bakers sits where the dough is extensible enough to expand and elastic enough to stay upright.
Open crumb is commonly credited to hydration and rarely earned by it. Large irregular holes come from adequate gluten development, sufficient but not excessive bulk fermentation, and gentle shaping that preserves the gas already produced. A wet dough that is underdeveloped produces a flat loaf with a dense wet streak. Anthes has seen more failed bakes from chasing hydration than from anything else, and his notebook shows better results at 74 percent with careful handling than at 82 percent with rushed handling.
Hydration also changes crust and bake time. More water means more steam released inside the loaf, which extends the time before the interior reaches the 96 to 99C range where starch gelatinization completes. A high hydration loaf usually needs a longer bake to avoid a gummy center, and the extra internal moisture produces a thinner, crisper crust that softens faster on the counter.
Ambient conditions matter more than most recipes admit. Flour picks up moisture from the air, so the same recipe run in a humid month behaves like a wetter dough. Anthes bakes in a dry climate and finds he runs slightly higher hydration than published recipes suggest for the same feel.
The reliable approach is to fix hydration for several bakes, learn how the dough feels at each stage, and change it only after everything else is consistent. Anthes records hydration, flour blend, and how the dough felt at shaping. The feel notes end up being the useful part.