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.
View original PDF Guide →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!