Reuse of eggshells in WCA
is it okay to add more vinegar to eggshells after the saturated vinegar has been drained off?
Top answer
No, the concentration would be weak. Pulverise and throw them in your worm farm.
From the KNF library
From the KNF library
Drafted by Claude from Office Hours and the books
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Sep 2026
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4 sources
The library describes each batch as a single pass.
- Mix 1 part toasted eggshells with 10 parts brown rice vinegar by weight. (Cho's Solutions, p. 13)
- Let them dissolve until the bubbling stops, then pour off and keep the liquid. (KNF Demystified, p. 40)
The finished liquid is neutral in pH, and its vinegar property is used up. (Pure KNF Manual, p. 51) Cho describes a completed WCA container as having nothing at the bottom. (Cho, Recipe, p. 62)
The library does not say whether drained shells can take a second dose of vinegar, or how strong that liquid would be.
Sources
- p. 13 Cho's Solutions · “Mix 1 part eggshells with 10 parts brown rice vinegar by weight”
- p. 40 KNF Demystified · “Allow to dissolve for several days until the eggshells stop bubbling. Pour off and retain the liquid and store out of direct sunlight.”
- p. 51 Pure KNF Manual · “After the reaction with the vinegar, the solution is then neutral in pH. This does not substitute for the other recipes that call for vinegar, that property has been used up”
- p. 62 Cho, Recipe · “The completed WCA container has nothing at the bottom”
