1 clean glass jar
1 loose-fitting lid or cloth cover
Whole wheat flour or rye flour
Unbleached all-purpose flour
Room-temperature filtered water
Kitchen scale
Day 1: Mix 50 g flour with 50 g water in the jar
Cover loosely
Let sit at room temperature for 24 hours
Day 2: Discard half of the mixture
Add 50 g flour and 50 g water
Mix well
Cover loosely
Let sit for 24 hours
Day 3: Discard half of the mixture
Add 50 g flour and 50 g water
Mix well
Cover loosely
Let sit for 24 hours
Day 4: Discard half of the mixture
Add 50 g flour and 50 g water
Mix well
Cover loosely
Let sit for 24 hours
Day 5: Discard half of the mixture
Add 50 g flour and 50 g water
Mix well
Cover loosely
Let sit for 24 hours
Day 6: Discard half of the mixture
Add 50 g flour and 50 g water
Mix well
Cover loosely
Let sit for 24 hours
Day 7: Feed every 12 hours if bubbling and rising
Discard half before each feeding
Add 50 g flour and 50 g water each feeding
Use when it doubles in size within 4 to 8 hours after feeding
Store at room temperature if baking daily
Feed once daily at room temperature
Store in the refrigerator if baking weekly
Feed once weekly when refrigerated