The Bulk Of It

You’ve nailed your starter routine. You understand the mechanics of mixing. But then comes the most elusive—and arguably most critical—step in sourdough baking: knowing when bulk fermentation is done.

This stage, often overlooked in favor of simpler talking points like starter feeding or stretch-and-fold routines, is the true fulcrum of fermentation. Mastering it separates decent bread from exceptional bread. And yet, it’s the hardest for home bakers to learn because, unlike other variables, it’s not easily reduced to a formula. Over the years, many methods have emerged in an effort to remove this ambiguity. But are they helping or hindering progress?

The Rise of Prescriptive Methods

Chad Robertson’s Tartine Bread (2006) changed everything. His narrative-driven, “soul surfer” approach gave home bakers a poetic, hands-on view of the sourdough process—one that tried to explain not just the how, but the why. The method emphasized feel, observation, and rhythm. For many, it became the sourdough bible.

Then came Ken Forkish’s Flour, Water, Salt, Yeast (2012), which introduced the now-popular overnight bulk fermentation method. It promised simplicity and accessibility. With shaping and baking pushed to the next morning, it appealed to busy people who still wanted to bake “real” bread.

Emilie Raffa’s Artisan Sourdough Made Simple (2017) followed, adapting Forkish’s method into a lower-hydration, lower-difficulty version. Elaine Boddy’s “Master Recipe” arrived shortly after, closely mirroring Raffa’s formula while adding a cold-start bake. These methods made sourdough feel easier, more hands-off—and to some extent, they worked. The problem? They removed the baker from the bulk fermentation process almost entirely.

The Problem With “Set-It-and-Forget-It” Fermentation

While the overnight method may produce passable bread, it doesn’t teach anything about fermentation. You mix the dough, go to bed, and hope for the best. If the dough over- or under-ferments, there’s little you can do except try again and tweak blindly.

In this sense, the overnight bulk fermentation method is anti-educational. It’s great if your goal is just a loaf of bread. But if your goal is to become a better baker, it teaches you nothing about how dough behaves, how temperature and hydration influence fermentation speed, or how to course-correct in real time.

Even the more intentional Tartine-style approach, when followed prescriptively, falls short for the home baker. Why? Because it was developed around bakery-strength starters maintained at warm temperatures and fed multiple times daily—conditions that most home bakers don’t replicate. Our group of moderators in the Sourdough Geeks group once followed the original Tartine method to the letter and all ended up with under-fermented loaves.

Bulk-O-Matic and the Quest for Quantification

In 2021, Tom Cucuzza of The Sourdough Journey built on the Tartine framework with his Bulk-O-Matic method—a volume-based system designed to help bakers determine when to end bulk based on percentage rise. It’s logical and measurable. And Tom himself emphasizes that it’s meant as a starting point—not gospel.

But in practice, many bakers treat it as a rulebook. The charts circulate online with no context. What’s lost is the fact that these systems are calibrated to specific doughs, flour types, starter strengths, and environments. Change one variable, and the chart no longer applies.

This is the core limitation of all prescriptive bulk fermentation methods: they only work within a very narrow definition of sourdough—typically a country loaf using mostly refined flour, around 9% pre-fermented flour, a warm bulk, and a cold final proof. The moment you alter any of those conditions—hydration, flour type, starter ratio—the metrics fall apart.

So What Actually Works?

The best way to learn how to read bulk fermentation is to stop looking for shortcuts and start paying attention. There is no perfect formula because every dough is different—even the same formula will behave differently on two different days. The only constant is you, the baker.

Here are key ways to develop the skill:

1. Start with a simple, repeatable formula

Bake the same dough repeatedly. This consistency allows you to isolate variables and notice patterns.

2. Maintain your starter consistently

Feed it the same way, at the same time, and at roughly the same temperature—especially in the final 1–2 feedings before mixing.

3. Control temperature

Track the ambient and dough temperatures throughout bulk fermentation. Warmer doughs ferment faster. Cooler doughs need more time. Use this to your advantage rather than letting it control you.

4. Use time and temperature as a guide

This is the method favored by professional bakers and writers like Maurizio Leo, who began with Tartine but refined his approach through repetition and careful observation. Under consistent conditions, time and temperature give a reliable framework—but they must be adjusted as conditions change.

5. Learn the cues

Watch how the dough rises. Look for a change in texture—smooth, airy, and jiggly. Feel the difference when shaping: a well-fermented dough is strong but elastic, with visible gas pockets inside. Most importantly, trust your senses. Sight, touch, and smell will tell you more than any chart ever will.

Conclusion: Bulk Fermentation Is an Art—Learn It Like One

Prescriptive methods like Tartine, Bulk-O-Matic, and overnight recipes are valuable tools—but they are just that: tools, not truths. They can help you get started, but they cannot replace observation, repetition, and hands-on learning.

The only way to truly master bulk fermentation is to be present for it—to watch, to feel, to adjust, and yes, to make mistakes. But with time, you’ll no longer rely on someone else’s schedule or someone else’s chart. You’ll learn to read the dough in front of you—and that’s when baking gets really exciting.