The Bulk-O-Matic System
Bulk fermentation is the most critical step in sourdough baking. To master it, we use The Sourdough Journey's Bulk-O-Matic system—a 9-factor approach to "read the dough" rather than watching the clock.
How It Works
Most recipes give you a time (e.g., "proof for 4 hours"). But fermentation speed depends entirely on temperature and starter strength.
Instead of guessing, evaluate your dough against these 9 criteria. When most of them pass, your bulk fermentation is done.
Calculator Modes
Regular mode uses a temperature chart with interpolation for quick estimates.Advanced mode adjusts time with dough temperature, room temperature, hydration, and starter percentage.
Advanced mode is anchored to the regular chart at each dough temperature, then adjusted by hydration, starter percentage, and room temperature (baseline: 75% hydration, 20% starter, 72F room temp). Extra cold correction is applied below 60F.
Assumptions caveat: estimates align best around 20% starter and a room-temperature workflow near72F. Strong, active starters may ferment faster than estimated.
1. Temperature
Dough temperature drives fermentation speed. Maintain 75-82°F for optimal results. If cooler, it will take much longer.
2. Time
Use our calculator to get an estimated window based on your temp. This is your rough guide, not a rule.
3. Percentage Rise
The most reliable metric. For strong flour, look for 30-50% volume increase. Weaker flours need less rise (25-30%).
4. Domed Shape
The edges should slightly slope down, creating a convex 'dome' effect, showing internal pressure.
5. Bubbles (Top)
You should see scattered gas bubbles on the surface. If it's covered in bubbles, it might be over-proofed.
6. Bubbles (Sides)
In a glass container, you'll see uneven bubbles throughout the dough structure.
7. Wobble Test
Shake the bowl. The dough should jiggle like Jell-O or a waterbed, showing it's aerated and loose.
8. Tactile/Sticky
Touch it with a wet finger. It should feel tacky (like a post-it note) but not wet/messy. It should release cleanly.
9. Smell
It should smell sweet, yogurty, or fruity. If it smells like alcohol or nail polish remover, it's over-proofed.
Pro Tip: The Aliquot Jar
Pinch off a small piece of dough (40g) right after mixing and put it in a small, straight-sided spice jar. Mark the starting height. It's much easier to measure "50% rise" in a small jar than in a large, curved bowl. When the jar hits the target, your main dough is ready!