Bulk Fermentation Explained: Watch the Dough, Not Just the Clock
You’ve mixed your dough, done your folds and checked the time. Now comes the question: is it ready to shape, or does it need longer?
Bulk fermentation is the first rise of your bread dough, before you divide and shape it. It gives fermentation time to develop the dough’s flavour and fill it with gas. The useful signs are a change in volume, bubbles and a dough that becomes noticeably puffier.
The clock helps you organise your bake. The dough tells you how that bake is progressing.
This guide focuses on wheat-based sourdough, particularly our beginner recipe. Gluten-free dough needs its own recipe and handling instructions.
What does “bulk fermentation” mean?
“Bulk” simply means the dough is kept together as one batch. You are still bulk fermenting if that batch makes just one loaf.
The yeast and bacteria from your starter continue working after you mix them into the dough. Gas builds up, flavour develops, and the dough changes. A wheat dough’s gluten network helps hold that gas inside it.
If you’ve read why a sourdough starter rises and falls, the gas production will sound familiar. But bread dough is not a jar of starter: don’t wait for your dough to reach its maximum rise and collapse before shaping it.
You want to leave room for the fermentation that continues through shaping and the final proof.
When does bulk fermentation start?
Fermentation is underway as soon as the starter is mixed into the dough. For your baking notes, record that time. Don’t start a fresh fermentation clock after the last fold.
There is one useful distinction between the two mixing methods in our beginner recipe:
- By hand: The starter goes in before the initial rest, so fermentation is happening during that rest and throughout the folds.
- With a stand mixer: The initial flour-and-water rest contains no starter. Start counting when the starter is added, not when you first mix the flour and water.
Recipes may give the resting stage after folds a separate heading, but the microorganisms haven’t been waiting for that heading to start work.
Bulk fermentation ends when the dough is divided or pre-shaping begins. Fermentation itself does not stop, but the dough has moved into the next stage of the process. After dividing and pre-shaping, the dough is usually given a short bench rest before final shaping.
How do I know when bulk fermentation is done?
Look at a combination of signs. You don’t need a perfectly smooth surface or a particular number of bubbles.
A clear increase in volume
Our Beginner Sourdough Recipe calls for approximately 70% rise at a dough temperature of around 25–27°C. That means the dough grows to roughly 1.7 times its starting volume, not twice its starting volume.
For example, dough that begins at the 1-litre mark would reach about 1.7 litres after a 70% rise. Its weight has not increased by 70%. The extra volume comes from gas held in the dough.
Use that target alongside the other signs below. It belongs to this recipe and its process, rather than being a universal target for every flour, temperature and proofing method.
The amount of rise should always be read in the context of the dough you are making. The larger dough shown below is an 80% hydration spelt dough. The smaller dough is a 78% hydration Hellfire dough intended for baguettes. They contain different quantities of dough and use different flour blends, so they should not be compared as if one is the before photo and the other is the after photo.
Watch how your own dough changes from its starting condition. Flour choice, hydration, dough strength, temperature and the quantity of dough can all affect what fermentation looks like.
Bubbles and a puffier appearance
Look through the sides of your container as well as at the top. You may see bubbles against the walls, small blisters at the surface and a dough that looks fuller than it did after mixing.
You don’t need big bubbles everywhere. A few surface bubbles alone don’t tell the whole story either. Compare the dough with its earlier condition and check whether its volume has increased.
Look for bubbles distributed through the sides of the dough, not only a few bubbles on its surface. Combine this with its increase in volume, texture and movement. No single bubble or percentage measurement should be treated as a pass-or-fail test.
Some movement when you gently move the container
A gentle wobble can help show that the dough has become aerated. It should look less like the dense mixture you started with.
The amount of wobble depends on the flour and how wet the dough is, so don’t turn this into another test you have to pass. Read it alongside the rise and visible bubbles.
Make the rise easier to see
A clear, straight-sided food-safe container is useful because changes in level are easier to compare. A bowl works too, but its widening sides make a percentage increase harder to judge.
Choose a container that leaves plenty of room for the dough to expand. A very light coating of oil can help dough release from a plastic container. Glass and ceramic containers will often release cleanly without oil, although this depends on the dough and the surface.
Use the same container through the process where practical. Mark an early reference level once the mixed dough has settled, and take a side-on photo. In these photographs, the top edge of the tape marks the starting level. The tape gives you a fixed reference even when the dough relaxes, spreads or changes shape after folding. Keep the dough covered between checks.
Folding gathers the dough into a different shape and may release some gas. A tall mound immediately after a fold is not the same as fermentation rise. Let it relax before comparing levels, and don’t reset your target after every fold.
This is an estimate to help you learn, not a laboratory measurement. Consistent photos and notes are more useful than arguing with yourself over the last few millimetres.
How long should it take?
Allow several hours in your baking plan, but don’t treat a fixed number as the finishing line. The temperature of the dough, the amount and activity of your starter, and the flour all affect its progress.
For the hand-mixed beginner recipe, the scheduled folds take place over three hours. Those hours count towards fermentation. Finishing the folds doesn’t automatically mean bulk fermentation is finished, and it doesn’t mean you must add another full block of hours either.
Check what has changed. Has the dough risen? Are bubbles developing? Is it becoming puffier?
If it is still cool and showing little change, it may need more time. If it is already well advanced, don’t leave it unattended simply because you expected it to take longer.
Measure the dough temperature, not just the room
A kitchen thermometer tells you about the air nearby. A clean food probe thermometer tells you about the dough itself.
These measurements describe two different things. Room temperature affects how quickly the dough gains or loses heat, while the temperature inside the dough gives a more direct indication of the conditions experienced by the yeast and bacteria.
The desired final dough temperature for this bake was calculated before mixing so the water temperature could be adjusted accordingly. This helps create more consistent fermentation conditions from one bake to the next.
Cold water can leave your dough cooler than the room. Mixing can warm it. Moving the bowl to a warmer spot doesn’t instantly warm the centre of the dough.
Within a suitable baking range, warmer dough generally ferments faster and cooler dough more slowly. That is why a routine that worked last week can feel quite different on a warmer day. Take a temperature reading after mixing and again if progress seems unexpectedly slow or fast.
Avoid direct sun and uncontrolled heat. A steady, comfortably warm location is easier to learn from than a bowl that keeps moving between hot and cold spots.
Keep your first few bakes consistent
You will learn more easily if you can compare one bake with the next.
- Weigh your ingredients. Digital scales are particularly important when you’re starting out. Cups and guesses can change the dough before fermentation even begins.
- Use a freshly fed, active starter. Our starter-readiness guide explains the signs to look for before mixing.
- Stick with one recipe and flour. Changing flour, water and starter quantities together makes it harder to understand the result.
- Keep a short record. Note when the starter went in, the dough temperature, the approximate rise at shaping and anything unusual about the finished loaf.
- Check more often as the dough progresses. An occasional check early on can become a closer watch once the rise is obvious. You don’t need to hover over it all day.
If you need equipment, our digital kitchen scales help keep quantities consistent, and a dough scraper is handy for getting dough out of the bowl. Use what you already have if it does the job.
What happens after bulk fermentation?
Follow your recipe through pre-shaping, the bench rest, final shaping and proofing. Those steps still matter. Bulk fermentation prepares the dough for them; it doesn’t replace them.
Our beginner recipe recommends an overnight proof in the fridge after shaping. Cooling slows fermentation, but warm dough takes time to cool through. Putting it in the fridge is not an instant stop button.
That is another reason not to keep chasing more rise in the bowl. Follow the recipe’s target, then watch how the whole process works in your kitchen.
What about rye, spelt and gluten-free dough?
Don’t expect every dough to feel or move like a mostly white wheat dough. The flour blend changes its structure and handling, so follow the recipe written for it.
In particular, gluten-free dough doesn’t have a wheat gluten network. Don’t use a wheat-style stretch or wobble as a compulsory readiness test. Use our gluten-free recipes and the instructions for your specific flour blend.
Quick questions
Do stretch and folds count as bulk fermentation?
Yes. Fermentation continues during the folds and the rests between them. The last fold does not start the clock again.
Does my dough have to double?
Not for our beginner recipe, which uses approximately 70% rise under its stated conditions. Follow your recipe’s target instead of applying the starter’s doubling guideline to bread dough.
Can I leave it overnight on the bench?
Don’t assume an overnight rest will suit your usual recipe. Warm dough may progress much further than you expect while you sleep. While learning, choose a bake you can observe and follow the recipe’s planned proofing method.
My dough is smooth after mixing. Is it ready to shape?
Not necessarily. Mixing can develop a smooth, elastic dough before much fermentation has occurred. You still need to observe its rise and aeration.
Should I keep folding until it rises enough?
No. Folds develop strength; they are not a way to hurry fermentation. Follow the recipe’s mixing and folding method, then give the dough time to develop without repeatedly disturbing it.
Every bake teaches you something
Bulk fermentation gets easier when you stop treating the clock as a verdict and start noticing the dough in front of you.
Use scales, take your time, note the conditions and have fun. Choose our Beginner Sourdough Recipe for your next bake and keep a few notes to compare afterwards.
We really believe that if your loaf tastes great, then it is great. Learning to read fermentation helps you build on that, one loaf at a time.
Let’s bake some bloody good bread!