How to Tell When Bulk Fermentation Is Done

Bulk fermentation is the long rise between mixing a sourdough and shaping it, and ending it at the right moment matters more than any other decision in the bake. Stop too early and the loaf is dense and gummy with a few big tunnels; wait too long and the dough turns slack, sticky and hard to shape, then bakes flat.

Recipes give a time, but the time is only a guess built around one starter, one flour and one kitchen temperature. This guide explains the physical signs that show bulk is done, how to use a straight-sided container and a small sample jar to measure rise, and how those signs shift with whole grains and higher hydration.

Why the clock is unreliable

Fermentation speed depends on the strength of your starter, how much of it goes into the dough, the flour and above all the dough's temperature. A difference of just 2 or 3 degrees Celsius can change the length of bulk by an hour or more. That is why a recipe that says five hours can be right in one kitchen and wrong in the next.

Measure dough temperature right after mixing. Between about 24 and 26°C (75 and 78°F), a dough with roughly 20 percent levain often finishes in 4 to 6 hours. Cooler dough takes longer, warmer dough less. Use the time as a guide for when to start checking, then rely on the signs below.

Measuring rise

Volume increase is the most objective sign. In a straight-sided container, mark the dough level with tape right after the last fold. Bulk is usually done when the dough has risen 50 to 75 percent above that mark. A doubled white dough has often gone too far for a free-form loaf, though it may still work in a loaf pan.

In a bowl, rise is hard to judge because the sides flare. A small sample jar solves that. Right after mixing, drop a walnut-sized piece of dough into a narrow straight jar, press it flat, mark the level and keep it beside the main dough. When the sample has risen by the target amount, check the main dough for the other signs.

• Straight-sided container with a tape mark at the start of bulk
• Narrow sample jar as a second reference
• Target: about 50 to 75 percent rise for white flour, less for whole grain

Reading the surface and edges

A dough near the end of bulk is domed and smooth rather than flat. Where it meets the container, the edges curve upward slightly, like a meniscus turned upside down. Bubbles of different sizes show on the surface, and you can see an airy, honeycomb pattern of bubbles through the sides of a clear container.

Gently tilt or shake the container. A finished dough wobbles and jiggles as a unit, with a loose, airy movement. An underfermented dough shifts as a dense block; an overfermented dough sloshes and may look wet and flat with large bubbles breaking at the surface.

How the dough feels

Wet your hand and slide it under one edge of the dough. Ready dough feels light, puffy and elastic, and releases easily from the container. When you tip it onto the counter, it holds a soft mound and does not immediately spread into a puddle. You can feel gas bubbles beneath your fingers.

Underfermented dough feels heavy and tight, springs back fast when pressed and has few visible bubbles. Overfermented dough feels sticky, weak and gassy, tears easily and refuses to tighten when you preshape it.

Adjusting for flour and hydration

Whole wheat, rye and spelt doughs ferment faster because bran and germ feed the microbes, but their gluten is weaker, so they rise less before they are ready. For a dough with half or more whole grain, look for about 30 to 50 percent rise along with plenty of bubbles. High-hydration white doughs can rise a bit more and look very jiggly before they are done.

Added sugar, fat, cheese or fruit can slow fermentation. Enriched sourdough doughs often need a longer bulk and may never look as bubbly as lean dough.

What to do if you missed it

If the dough is underfermented at the planned shaping time, wait. Check every 30 minutes. If you must leave, refrigerate it and let it finish fermenting at room temperature later; it will take longer, but cold does not reset the progress already made.

If it has overfermented, shape gently with a little flour, skip the long cold proof and bake soon in a loaf pan, which supports a weak dough. Overfermented dough can also be pressed into a sheet pan with olive oil and baked as a focaccia-style flatbread.

Common questions

Does the poke test work for bulk fermentation?

The poke test is designed for the final proof of a shaped loaf. During bulk, the dough is not shaped and has no surface tension, so a poke tells you little. Rely on rise, bubbles, domed edges and jiggle instead.

Should bulk fermentation double the dough?

For most free-form white sourdough, doubling is too far. A rise of about 50 to 75 percent leaves enough fermentation power for the final proof and oven spring. Pan loaves and enriched doughs can go a little further.

Can bulk ferment overnight on the counter?

Yes, with less starter and a cool room. Around 5 to 10 percent levain and a kitchen at 18 to 20°C (64 to 68°F) can give an 8 to 12 hour bulk. Check it early the first time, since every starter differs.