# Case hardening

> A drying fault where a bud's surface dries too fast and seals, leaving the core wet; buds feel dry, then rehydrate and risk mould in the jar.

- Canonical: https://genetixbay.com/knowledge/glossary/case-hardening.html
- Also written: case hardened, case-hardened buds, crispy outside wet inside, outer dry inner wet
- Glossary category: Harvest, drying and curing · Evidence: Grower practice
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Case hardening is a term borrowed from timber and food drying. When the surface of a bud loses water faster than the core can supply it, the outer tissue dries and tightens into a shell that slows further drying. The bud feels crisp outside while the centre is still moist.

## In practice

Symptoms: buds that feel jar-ready after only a few days, then go spongy and damp once sealed; jars whose [equilibrated RH](https://genetixbay.com/knowledge/glossary/equilibrium-relative-humidity.md) climbs far above 65% overnight; dense [colas](https://genetixbay.com/knowledge/glossary/cola.md) with a damp core when cut open.

Causes: warm, dry [drying rooms](https://genetixbay.com/knowledge/glossary/drying-room.md); fans blowing directly on buds; wet-trimmed small buds on racks in low humidity; dry periods of only 3-5 days.

[Prevention](https://genetixbay.com/knowledge/glossary/cultural-control.md): slow the dry, about 15-21 °C (60-70 °F) and 55-62% [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md), with gentle indirect airflow, aiming for roughly 7-14 days. Leave more leaf and stem on ([dry trim](https://genetixbay.com/knowledge/glossary/dry-trim.md), [whole-plant hang](https://genetixbay.com/knowledge/glossary/whole-plant-hang.md)) in dry climates.

If it happens: jar the buds and burp often, or spread them on a tray in a humid room for short sessions, letting the moisture even out. Check closely for mould.

## Don't confuse with

- **Over-drying**: dry all the way through.
- **Sweat**: moisture moving outward in a jar, part of a normal cure.
- **Mould**: a possible consequence of case hardening, not the same thing.

## Related terms

[Drying room](https://genetixbay.com/knowledge/glossary/drying-room.md), [60/60 rule](https://genetixbay.com/knowledge/glossary/60-60-rule.md), [Over-drying](https://genetixbay.com/knowledge/glossary/over-drying.md), [Sweat](https://genetixbay.com/knowledge/glossary/sweat.md), [Water activity](https://genetixbay.com/knowledge/glossary/water-activity.md)

## Read more

- [Drying cannabis: the 60/60 method and water activity](https://genetixbay.com/knowledge/harvest-cure/drying.md)

## Sources

1. University of Georgia (thesis). Effects of drying method and storage on cannabinoids and terpenes in hemp. https://openscholar.uga.edu/record/27813