# Humidity pack

> A salt-solution sachet sold to hold a sealed container at a fixed relative humidity; GenetixBay regards them as a marketing gimmick that robs terpenes.

- Canonical: https://genetixbay.com/knowledge/glossary/humidity-pack.html
- Also written: humidity packs, two-way humidity pack, two-way humidity control, humidity sachet, 62% pack, 58% pack, humidity control pack
- Glossary category: Harvest, drying and curing · Evidence: Myth
- 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"

A humidity pack is a sealed pouch of saturated salt solution behind a vapour-permeable membrane. It absorbs or releases water to pull a closed container's air toward a set [RH](https://genetixbay.com/knowledge/glossary/relative-humidity.md), commonly 58% or 62%. "Two-way" means it can both add and remove moisture.

## In practice

They are widely sold for jars and storage. GenetixBay doesn't recommend them.

House position (Myth for the quality claims):
- They are a marketing gimmick. The pro-pack data is essentially the manufacturer's own.
- They rob [terpenes](https://genetixbay.com/knowledge/glossary/terpene.md): the pack and its membrane give the jar's volatiles somewhere else to go.
- Curing is a slow decline in moisture, not holding moisture constant, which is exactly what a pack is designed to do.

If buds are [too dry](https://genetixbay.com/knowledge/glossary/over-drying.md) and you need to add moisture, put a fresh bud in the jar instead. To keep stock in range, start with a good dry, fill airtight [glass jars](https://genetixbay.com/knowledge/glossary/curing-jar.md) well, and store them dark and cool.

## Don't confuse with

- **Desiccant**: removes moisture only, for seeds and electronics.
- **Hygrometer**: measures RH, doesn't control it.
- **Water activity target**: the goal (0.55-0.65 aw), not a product.

## Myth check

"Humidity packs keep your stash fresher" is a Myth in the house view. A well-dried, well-cured bud in a full, airtight, dark jar does the job. See [curing and burping](https://genetixbay.com/knowledge/harvest-cure/curing-burping.md) and [Mythbusters](https://genetixbay.com/knowledge/mythbusters.md).

## Related terms

[Curing](https://genetixbay.com/knowledge/glossary/curing.md), [Burping](https://genetixbay.com/knowledge/glossary/burping.md), [Water activity](https://genetixbay.com/knowledge/glossary/water-activity.md), [Terpene loss](https://genetixbay.com/knowledge/glossary/terpene-loss.md)

## Read more

- [Curing and burping: jars, humidity and how long](https://genetixbay.com/knowledge/harvest-cure/curing-burping.md)
- [Long-term storage: keeping cured flower potent and aromatic](https://genetixbay.com/knowledge/harvest-cure/long-term-storage.md)

## Sources

1. ASTM D8197. Standard Specification for Maintaining Acceptable Water Activity (aw) Range (0.55 to 0.65) for Dry Cannabis Flower. ASTM International. https://store.astm.org/d8197-22.html
2. ASTM International, Standardization News. Two cannabis standards you should know about (salt-based humidity control sachets for aw below 0.68). https://sn.astm.org/node/2445/printable/print