# Bubble hash

> Bubble hash, or ice water hash, is a solventless concentrate made by separating trichome heads from cannabis in cold water and collecting them on graded mesh bags.

- Canonical: https://genetixbay.com/knowledge/glossary/bubble-hash.html
- Also written: ice water hash, ice hash, water hash, ice-water hash, IWH, ice water extraction
- Glossary category: Processing · Evidence: Established
- 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"

Bubble hash is [hash](https://genetixbay.com/knowledge/glossary/hash.md) made with ice water. Cold makes [trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md) brittle so they snap off the plant under gentle agitation; the heads, being denser, separate from plant matter in the water, and the slurry is filtered through a series of mesh bags graded in microns. Each bag catches a size fraction of heads, which is then dried. The name comes from the way high-grade material bubbles when heated.

## In practice

Hash makers describe grades by micron fraction and by melt quality, often on an informal one-to-six-star scale. The middle fractions usually hold the cleanest, most intact heads; the finest and coarsest fractions carry more debris. Starting material can be dried flower, trim or [fresh frozen](https://genetixbay.com/knowledge/glossary/fresh-frozen.md) plants; fresh frozen gives "live" products. Russo et al. (2021) studied a fresh-frozen ice water method and reported that it preserved [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md) and [terpene profiles](https://genetixbay.com/knowledge/glossary/terpene-profile.md) well. GenetixBay defines the product but doesn't provide processing steps.

## Don't confuse with

- **Dry sift**: separated with dry screens, no water.
- **Full melt**: the top grade of bubble hash (or [dry sift](https://genetixbay.com/knowledge/glossary/kief.md)), not a separate method.
- **Rosin**: may be pressed from bubble hash, but is a further product.

## Related terms

[Micron bags](https://genetixbay.com/knowledge/glossary/micron-bags.md), [Full melt](https://genetixbay.com/knowledge/glossary/full-melt.md), [Trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md), [Live rosin](https://genetixbay.com/knowledge/glossary/live-rosin.md), [Solventless](https://genetixbay.com/knowledge/glossary/solventless.md), [Fresh frozen](https://genetixbay.com/knowledge/glossary/fresh-frozen.md)

## Sources

1. Russo EB, Plumb J, Whiteley VL. 2021. Novel solventless extraction technique to preserve cannabinoid and terpenoid profiles of fresh cannabis inflorescence. Molecules 26(18):5496. https://doi.org/10.3390/molecules26185496
2. Clarke RC. 1998. Hashish! Red Eye Press, Los Angeles (updated edition 2010).