Dave's Thirty-Year Culture and the Move I Had to Make

Sourdough Bread Baking

Dave handed me a mason jar at the chess club last Tuesday. Inside, a pale beige slurry with bubbles clinging to the glass like condensation on a cold drink. “Thirty years old,” he said. “Well, the lineage is. I’ve been feeding this thing since the first lockdown.”

He’d shown me photos of his loaves before—the kind where you can see the open crumb structure and the caramelized crust line that bakers call “the ear.” I’d looked at them the way I look at a chess position, reading the distribution of holes, the tension between crust and crumb. When he mentioned hydration ratios and bulk fermentation timing, I realized there was a whole system underneath that I hadn’t seen.

The jar is on my counter now. This post is about what’s actually happening inside it.

Baker’s Percentage: The Notation That Makes Scaling Trivial

Every bread recipe can be expressed as a ratio where flour equals 100%. Everything else—water, salt, starter—is a percentage of that flour weight.

A typical sourdough formula:

Ingredient	Baker’s %	For 500g flour
Flour	100%	500g
Water	75%	375g
Salt	2%	10g
Starter	20%	100g

That 75% is called the hydration. Lower hydration (65%) makes a stiffer dough that’s easier to shape but produces a tighter crumb. Higher hydration (80%+) gives you those open, irregular holes, but the dough handles like wet cement.

The beauty of this notation: to double the recipe, double the flour and recalculate. To scale to 800g of flour, multiply everything by 1.6. No conversion tables, no mental arithmetic about whether “2 cups” means sifted or packed.

When I built the Zugzwang Cadence Etudes, I discovered that FEN notation encodes a chess position in a single line of ASCII—piece placement, castling rights, move number, everything a computer needs to reconstruct the game state. Baker’s percentage works the same way. The formula is the recipe, compressed to essentials.

The Fermentation Window Is Temperature-Dependent

Most recipes say “bulk ferment for 3-4 hours.” This is useless information.

What matters is dough temperature. At 24°C, bulk fermentation takes about 4 hours. At 21°C, closer to 6. At 18°C, you might need 8 or more. The yeast and bacteria don’t read clocks.

Professional bakers work backwards from a target called DDT (desired dough temperature), usually 24-26°C for sourdough. They calculate water temperature based on room temperature, flour temperature, and friction from mixing:

Water temp = (DDT × 3) - Room temp - Flour temp - Friction factor

The friction factor varies by mixer type—typically 10-25°C for a stand mixer, lower for hand mixing. This is why bakeries have thermometers everywhere. Temperature is the control variable.

At home, I’m using a probe thermometer and a spreadsheet. The jar of starter sits next to a BME280 sensor left over from a previous project—which, looking back, was already preparing me for this exact moment.

What “100% Hydration Starter” Actually Means

Dave’s instructions: “Feed it equal parts flour and water by weight.”

This produces a starter at 100% hydration—the flour to water ratio inside the jar itself is 1:1. It should double in volume within 4-8 hours at room temperature, then slowly collapse as the yeast exhausts available sugars.

The rise-and-fall cycle is the feedback loop. A healthy starter at peak activity:

Has doubled or tripled in volume
Shows a domed surface with visible bubbles
Passes the “float test” (a spoonful floats in water)
Smells tangy but not sharp—more yogourt than vinegar

If it smells like acetone or nail polish remover, acetic acid has taken over. The fix is more frequent feedings or cooler temperatures to slow bacterial activity relative to yeast.

The Autolyse Rest: Enzymes Before Effort

Before adding salt and starter, you can mix just flour and water and let it sit for 20-60 minutes. This rest is called autolyse (from the Greek autolysis, self-digestion).

During this window:

Amylase enzymes break starches into sugars the yeast can eat
Protease enzymes begin restructuring gluten proteins
The flour fully hydrates without mechanical work

The result is a dough that develops strength faster once mixing begins, with better extensibility and a more open crumb. Salt inhibits these enzymes, which is why it’s added after—you want the chemistry to run before you stop it.

Raymond Calvel formalized this technique in 1974, but bakers had been resting doughs for centuries. They didn’t know about amylase. They just knew the bread came out better.

The jar on my counter has been fed for sixteen hours. Small bubbles are forming along the glass. Tomorrow I’ll know if it’s strong enough to leaven a loaf, or if it needs another day of feedings to wake up.

Dave’s thirty-year-old culture has a new home. Now I have to learn not to kill it.