Field Note2026-03-05 · 5 min read
Stucco Storage and Aging: A Quiet Variable
Hemihydrate doesn't last forever in a silo. Here is what changes, and what to do about it.
LM
L. Marín
Application Chemist
Fresh stucco out of the kettle is more reactive than stucco that has spent two weeks in storage. The mechanism is mostly rehydration of surface hemihydrate to dihydrate from ambient moisture, which inhibits subsequent dissolution.
The practical effect: morning runs on Monday after a weekend shutdown often need slightly more accelerator than Friday afternoon. A small adjustment, but worth knowing about. Date your silos. Rotate. Don't let the silo run below 30% for more than a day if you can help it.