Temperature × recipe

Pain au Levain at 8895°F

Adjusted timing: 1.8h bulk + 4.7h proof (multiplier 0.39×).

Baseline bulk (76°F)
4.5h
Adjusted bulk
1.8h
Baseline proof
12h
Adjusted proof
4.7h
Multiplier
0.39×
Activity
extreme-mold-risk
Target hydration
72%
Bake temp
480°F

Why the timing shifts

Very hot — avoid. Mold risk rises sharply above 85°F. Fermentation outpaces structural development. Levain becomes unbalanced toward lactic acid producers, creating cloying sour flavor. Only use briefly for refreshing starters or if absolutely unavoidable. Move dough to cooler location, or skip this bake and wait for cooler conditions. If baking must happen, reduce levain to 8%, bulk 90 min max, get into refrigerator immediately after shaping.

Technique for Pain au Levain

Autolyse 60 min. Add levain (100% hydration, 15-20% of flour weight) and salt. 3 sets of stretch-and-folds. Total bulk 4.5h at 76°F. Shape tight boule, cold retard 12h. Bake in 480°F dutch oven: 22 min lid on, 22 min lid off.

Calculator pre-set to these values

Multiplier at 92°F
0.39×
Adjusted bulk ferment
1.8 h
Adjusted final proof
4.7 h
How the math works

Multipliers are piecewise-linear interpolations between reference points measured by Myhrvold et al. in Modernist Bread vol 3. 76°F is the baseline (1.0×); every 10°F drop roughly doubles fermentation time, and every 10°F rise roughly halves it.

Sources: Myhrvold, Modernist Bread vol 3 (temperature multipliers); Hamelman — Bread 3rd ed., Pain au Levain formula.