159 Micron (Bubble Hash Screen)
A common ice-water hash filtration size, roughly in the middle of the mature-trichome-head range, often prized for full-melt yields.
159 micron is one bag size in a stack — nothing magic about the number. It sits in the sweet spot where mature Cannabis trichome heads tend to collect, which is why washers talk about it. But screen size alone doesn't determine quality: starting material, wash technique, and drying matter far more. Treat '73–159' as a useful convention, not a grade. Full-melt can come from other fractions too.
Definition
A 159 micron screen is a mesh with 159-micrometer openings used in ice-water hash washing. In a standard bag stack, it sits above finer screens like 90, 73, and 45 micron, catching larger trichome heads (and some contaminant plant matter) while letting smaller resin heads pass through to lower bags. The number refers to the aperture size of the mesh, not the size of the resin itself.
Why this size exists
Cannabis capitate-stalked trichome heads — the glands that hold most of the cannabinoids and terpenes — typically measure roughly 50 to 120 micrometers in diameter, though ranges vary by cultivar and maturity Strong evidence[1][2]. A 159 µm screen therefore captures the largest intact heads plus small clusters of heads still attached together. Washers often combine the 73–159 µm fractions as the 'food grade' or 'full-melt' target range, because that band tends to contain the cleanest, most resin-dense material Weak / limited[3].
What 159 micron does
- Acts as an upper size cutoff, filtering out plant fragments, larger contaminants, and any resin clusters bigger than 159 µm.
- Retains the biggest usable trichome heads for the 'top' of the middle grade in a stack.
- When paired with a 73 µm bag below it, defines the popular '73–159' full-melt window used in hash rosin and solventless production Weak / limited[3].
What 159 micron doesn't do
- It does not guarantee full-melt. Melt quality depends on trichome maturity, freshness of starting material (fresh-frozen vs. dried), wash temperature, agitation, and drying Weak / limited[3].
- It does not make hash more potent than a finer screen — cannabinoid content depends on what resin is in the heads, not which bag caught them.
- It is not a legal or regulatory grade. Grades like '6-star' are visual/melt-based conventions, not screen-size definitions Anecdote.
Used in articles
See Bubble Hash, Ice Water Extraction, Hash Rosin, and Trichome for context on where the 159 µm screen fits in the solventless workflow.
Sources
- Peer-reviewed Livingston, S. J., et al. (2020). Cannabis glandular trichomes alter morphology and metabolite content during flower maturation. The Plant Journal, 101(1), 37-56.
- Peer-reviewed Tanney, C. A. S., Backer, R., Geitmann, A., & Smith, D. L. (2021). Cannabis Glandular Trichomes: A Cellular Metabolite Factory. Frontiers in Plant Science, 12, 721986.
- Reported Bienenstock, D. (2019). How to Make Hash: A Beginner's Guide to Solventless Extraction. High Times.
How this page was made
Generation history
Drafting assistance and fact-check automation are used, with a human operator spot-checking on a weekly basis. See how articles are made.
Related
- Bubble Hash — A solventless cannabis concentrate made by agitating frozen plant material in ice water to...