How to Use an Aliquot Jar for Bulk Fermentation

Short answer: an aliquot jar is a small jar with 30–50g of dough taken at the start of bulk. Mark the level. When the dough rises 50–60%, the bulk is done. It's the most reliable way to track fermentation visually.

What an aliquot jar is

An aliquot jar is:

• A small clear jar (4–8oz)
• Filled with 30–50g of your dough
• Marked at the starting level
• Watched throughout bulk

When the dough in the jar rises 50–60%, your main dough is at the same percentage rise.

Why this beats clock-watching

Clock-based bulk timing assumes:

• Standard kitchen temp
• Standard starter strength
• Standard recipe

Real life varies. The aliquot jar gives you visual proof of fermentation regardless of variables.

Setting up

You need:

• A small mason jar (8oz max)
• A rubber band
• A scale

After mixing dough:

• Pinch off 30–50g of dough
• Place in jar
• Smooth the top with a wet finger
• Mark the level with a rubber band

Where to place it

Put the aliquot jar:

• Next to your main dough (same temperature)
• In direct view (easy to check)
• On the counter, not in a basket

The jar should experience exactly what your main dough experiences.

Reading the rise

Most sourdough wants 50–60% rise in bulk.

Why 50–60% (not 100%)

After bulk:

• Shape (which degasses slightly)
• Cold retard (continues fermentation)
• Final proof (more rise)
• Bake (oven spring)

Total rise from initial mix to baked loaf is 200–300%. The bulk only needs to do part of it.

A common mistake

Some bakers wait for 100% rise in the jar. Result: over-fermented dough, weak shape, collapse in oven.

Stop at 50–60% rise. Trust the process.

When to mark the jar

Mark immediately after placing dough in the jar. Don't wait — the dough starts rising right away.

A rubber band around the jar at the dough level is the standard mark.

A clear jar matters

Use a clear glass jar:

• See bubbles forming
• See texture changes
• Track precisely

Frosted or colored jars hide the dough's progress.

How to know it's at 50%

Some methods:

• Mark at the 50% line in advance (use a sharpie)
• Compare to the rubber band level
• Eye it (with practice, accurate)

For precision: mark both the start and the 50% target on the jar.

What aliquot rise tells you

A jar at 50% rise but main dough looks different:

• Trust the jar (it's a smaller sample, more sensitive)
• Or shape the dough anyway
• Don't wait for visible main dough rise (it's slower to register)

A jar for proof too

Use the jar for final proof:

• After shaping, pinch off 20g of dough
• Mark the level
• Watch for 30–50% rise

When the proof jar rises that much, the main dough is ready to bake.

Cleaning the jar

After bulk:

• Discard the dough sample (compost or trash)
• Wash jar with hot soapy water
• Dry fully
• Reuse next bake

A dedicated aliquot jar lasts forever.

A 4-bake calibration

For your first 4 bakes:

• Use the aliquot jar
• Note when each bulk ends (rise %)
• Note the bread quality
• Identify the "right" rise for your starter and flour

After 4 bakes, you'll know exactly when to stop bulk for your specific recipe.

A side benefit: visible bubbles

The aliquot jar shows:

• Bubble activity (vigor of starter)
• Dough surface changes (fermentation progress)
• Smell (fermentation strength)

This is a learning tool as much as a timer.

When to skip the jar

If you're an experienced baker:

• Trust the touch and visual cues of the main dough
• Skip the jar for routine bakes

For new recipes, new flours, new schedules: always use the jar.

A small but mighty tool

The aliquot jar:

• Costs $3
• Takes 10 seconds to set up
• Eliminates guesswork
• Improves consistency

It's the most useful, underused sourdough tool.

A final note

Some bakers feel it's "cheating" to use an aliquot jar. It's not — it's measurement.

Pro bakeries use sensors. Home bakers use jars.

Try one for 3 bakes. You'll never go back to clock-only timing.