Drake's office hours give the ratio by weight: one part toasted eggshell to ten parts brown rice vinegar. (Office Hours Feb 2023, 48:51) A written recipe agrees. Mix 1 part eggshells with 10 parts brown rice vinegar by weight. (Cho's Solutions, p. 13)
Leo says weight fails because roasting changes it. The library agrees on the cause. Cooked shells become lighter by weight, so weigh them after toasting. (KNF Demystified, p. 40) (Office Hours Feb 2023, 48:51) The library also says ten parts, not nine, and one source gives the ten as weight and volume. (KNF Demystified, p. 40)
- Put the vinegar in the container first. (Cho, Recipe, p. 60)
- Add the shells slowly, a little at a time, so the bubbles do not overflow. (Cho, Recipe, p. 62)
- Dissolve for 7 days with a breathable lid, stirring daily. (Cho's Solutions, p. 13)
