01/18/2026
One of the most challenging stages in the entire process of sourdough making is the bulk fermentation stage.
This is where most beginners get confused, impatient, or unsure of what they’re seeing. And it’s also where many common problems start, dough that spreads, loaves that bake flat, sour bread with weak structure, or dough that feels perfect one minute and ruined the next.
The challenges in this stage usually include knowing when bulk actually starts, how long it should last, how to read dough instead of the clock, and how temperature, starter strength, and handling all interact.
Bulk fermentation begins the moment your starter is mixed into the dough. From that point on, fermentation and gluten development are happening at the same time. The goal of bulk is not just “letting the dough rise”. The goal is to build strength, trap gas, and develop enough fermentation so the dough can hold its shape later.
One of the biggest beginner mistakes is thinking bulk has a fixed time. It doesn’t. Bulk fermentation is controlled by temperature, starter strength, hydration, flour type, and how the dough is handled. A dough at 28°C will ferment very differently from one at 21°C. A strong starter at 1:2:2 will move faster than a mild starter at 1:5:5. This is why copying someone else’s timing often fails.
Another common challenge is over-fermentation. This usually happens when the dough is left too long, especially in warm kitchens. The dough may look airy and jiggly but feel weak, sticky, and hard to shape. By the time it goes into the oven, it has already used up its strength.
On the flip side, under-fermentation is just as common. The dough feels tight, doesn’t rise much, and springs poorly in the oven. This often happens when bulk is cut short because the baker is afraid of overdoing it, or when the starter is too weak or too cold.
Many beginners also struggle with surface drying and poor dough strength during bulk. If the dough isn’t covered properly, it can dry out and resist expansion. If folds are skipped or done too aggressively, gluten either doesn’t develop enough or gets damaged.
So what should you actually look for during bulk?
You’re watching for gradual volume increase, usually about 30–50%, not doubling. You want the dough to feel lighter, smoother, and more elastic with each fold. By the end of bulk, it should jiggle slightly when the bowl is shaken, show bubbles along the sides, and feel airy but still strong when handled.
Bulk fermentation ends when the dough has enough gas and strength to hold shape after preshaping, not when the clock says so.
The image attached include a simple guide you can use as a reference. It’s not a rulebook, just a way to orient yourself.
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The most important thing to understand is this: bulk fermentation is a relationship between time, temperature, and starter strength. You don’t control it by force. You guide it by paying attention.
Once you stop thinking “how long should bulk take?” and start thinking “what is my dough telling me?”, this stage becomes far less stressful.
End of post.
As always, I hope this helps someone.
