1. 1. Assess Your Starter’s Condition: Observe your starter for bubbles, smell (sour, yeasty, or nail polish remover), and the presence of hooch. A weak starter will have few bubbles, thin consistency, and possibly a strong smell or significant hooch.

2. 2. Discard Most of the Starter: Leave about 1-2 tablespoons (20-30 grams) of your weak starter in a clean glass jar. Discard more if you have a very large amount, ensuring enough remains to propagate.

3. 3. Feed with Equal Parts Flour and Water: For a standard feeding, add equal parts (by weight) of flour and water. For example, if you have 20 grams of starter, add 40 grams of unbleached all-purpose flour and 40 grams of filtered water. For very weak starters, consider a 1:2:2 or 1:3:3 ratio (starter:flour:water) for the first few feedings.

4. 4. Mix Thoroughly Until Combined: Use a spoon or spatula to mix the starter, flour, and water until thoroughly combined. Scrape down the sides of the jar to incorporate all dry flour. The mixture should be a thick, paste-like consistency, similar to pancake batter.

5. 5. Mark the Level and Place in a Warm Spot: Place a rubber band around the jar at the level of the freshly fed starter, or use a marker. Cover the jar loosely with a lid or plastic wrap. Place in a warm spot, ideally 75-80 F (24-27 C).

6. 6. Observe and Repeat Feeding: Check your starter every few hours for bubbles and a noticeable rise. A healthy starter doubles or triples in 4-8 hours. If activity is low, wait for some signs of life, then repeat steps 2-5. You may need to feed every 8-12 hours until it consistently doubles in 4-6 hours.

7. 7. Smell and Texture Cues: An active starter will have a pleasant, tangy, slightly sweet, and yeasty aroma, with a bubbly, airy texture. If it still smells strongly of acetone or is sluggish, continue feeding, potentially using the 1:2:2 or 1:3:3 ratio again.

8. 8. Confirm Readiness for Baking: Your starter is ready when it consistently doubles or triples in size within 4-6 hours after feeding, has a bubbly surface, and passes the “float test” (a small spoonful dropped into water floats).