# Micron bags

> Micron bags are fine-mesh filter bags graded by opening size in microns, used to separate and size trichome heads in ice water hash making and to filter rosin.

- Canonical: https://genetixbay.com/knowledge/glossary/micron-bags.html
- Also written: bubble bags, wash bags, hash bags, ice water bags, micron screens, filter bags
- 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"

Micron bags are filter bags made of mesh with a precisely rated opening size, measured in microns (µm; 1 µm = 0.001 mm). In [ice water hash](https://genetixbay.com/knowledge/glossary/bubble-hash.md) making they are used in a nested set of different grades so that each bag retains a different size fraction of [trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md) while plant debris and water pass or are held back. Similar but smaller bags are used to contain material in a [rosin](https://genetixbay.com/knowledge/glossary/rosin.md) press and filter the oil. [Dry sift](https://genetixbay.com/knowledge/glossary/kief.md) uses flat, framed screens on the same principle.

## In practice

[Hash](https://genetixbay.com/knowledge/glossary/hash.md) makers label each collected fraction by the bag it came from, for example "90 µm" or "120 µm", because the fraction indicates head size and usually quality. The best fractions vary by cultivar, since head size is partly genetic. Mesh quality matters: inconsistent weave mixes grades. GenetixBay defines the equipment and gives no wash procedures.

## Units and formula

Micron (µm) = one millionth of a metre. A 73 µm screen has openings 0.073 mm across.

## Don't confuse with

- **Mesh count (lines per inch)**: an older sieve rating that doesn't convert simply to microns.
- **Rosin bags**: the same principle, used for pressing rather than washing.

## Related terms

[Bubble hash](https://genetixbay.com/knowledge/glossary/bubble-hash.md), [Full melt](https://genetixbay.com/knowledge/glossary/full-melt.md), [Kief](https://genetixbay.com/knowledge/glossary/kief.md), [Rosin](https://genetixbay.com/knowledge/glossary/rosin.md), [Trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md)

## Sources

1. Clarke RC. 1998. Hashish! Red Eye Press, Los Angeles (updated edition 2010).