Asked by lukas.eriksson90 ·November 11, 2021 ·20.3k readers

How bubbly should WCA be?

I´m trying to make WCA and when I added the toasted eggshells to vinegar it bubbled like a lava lamp and was highly active for maybe 1,5 hours. 5 hours later it is bubbling, but the eggshells are not going up and down as much as before. Is it just an initial reaction when it goes crazy or is it supposed be highly active for longer than mine is?

The answer

Drake Weinert L4 Instructor · provisional Foundation · Nov 14, 2021 ✓ Marked as the answer

The initial reaction is quite explosive, so I recommend only adding a little vinegar to avoid having it spill over. After an hour or so, the reaction will slow, so then add the rest of the vinegar to get it to 1:10 ratio by weight. This reaction is rather quick, and will be complete in 3-5 days. The way to know it is done is by tasting it, and when the vinegar bite is gone, it is done. What you describe is normal in practice.

From the KNF library

From the KNF library Drafted by Claude from Office Hours and the books · Sep 2026 · 4 sources

The library says to let the shells dissolve for several days, until they stop bubbling. (KNF Demystified, p. 40)

Cho describes shells that move up and down continuously, emitting bubbles, while the calcium carbonate melts. (Cho, Recipe, p. 60) Bubbling that has slowed but not stopped means the shells are still dissolving. (KNF Demystified, p. 40) Cho also says a fluffy eggshell means carbon dioxide is dissolving into the vinegar. (Cho, Recipe, p. 60)

The library gives a longer timeline than the 3-5 days in the accepted answer. One source says to let it dissolve about a week. (Office Hours Feb 2023, 49:33) Another says to dissolve for 7 days and stir daily. (Cho's Solutions, p. 13)

The library does not say how long the first surge should last.

Sources

49:33 Office Hours (Feb 2023) — Eggshell Water-Soluble Calcium, Bone Char Calcium Phosphate · “let it dissolve about a week”
p. 40 KNF Demystified · “Allow to dissolve for several days until the eggshells stop bubbling.”
p. 13 Cho's Solutions · “Dissolve for 7 days with breathable lid • Stir & agitate daily”
p. 60 Cho, Recipe · “The eggshells may move up and down continuously emitting bubbles, and calcium carbonate melts.”