Kelsy's Kandy

Why Did My Honeycomb Sink Instead of Puff Up?

Honeycomb sinks or stays flat when the sugar syrup was not hot enough to expand the gas, when the baking soda was old, lumpy, or overmixed, or when the foam was knocked down by stirring or spreading after the soda went in.

By Kelsy Maruyama, Founder & Toffee Maker, Kelsy's Kandy
Reviewed by Jason Burns, Editorial Steward
Last updated Jul 20, 2026
Published by Kelsy's Kandy · Licensed under Citation License 1.0

What it means

  • If the syrup is below hard-crack (149C/300F) it lacks the heat energy to inflate and set the bubbles, so the foam deflates.
  • Old or clumped baking soda releases too little carbon dioxide, giving a dense, flat result.
  • Overwhisking or spreading the mixture pops the bubbles you just created and collapses the structure.

Action steps

  1. Cook to a verified 149-154C/300-310F before adding the baking soda.
  2. Use fresh, accurately measured, sifted baking soda.
  3. Whisk the soda in for only a few seconds, then pour immediately without stirring or spreading.

Risks & deadlines

  • Work fast once the soda is in — the reaction and set happen within seconds.
  • The syrup is dangerously hot; avoid splashes.

Source:

Last verified: 2026-07-20