159 Micron (Bubble Hash Screen)
Mesh screen used in ice-water hash washing to separate large trichome heads from finer material.
The 159 µm screen is a practical tool, not a quality guarantor. It catches larger trichome heads by size, but 'full-melt' or 'food-grade' status depends far more on trichome maturity, starting material freshness, wash technique, and drying—not the screen alone. Screen size is a filter; quality is made by method.
Definition
A 159 micron screen is a mesh with 159-micrometer openings used in ice-water hash washing. In a standard bubble hash bag stack, it sits above finer screens (90, 73, and 45 micron), catching larger trichome heads and some plant matter while allowing smaller resin heads to pass through to the bags below. The number refers to the aperture size of the mesh, not the diameter of the resin heads themselves.
Why this size exists
Cannabis capitate-stalked trichome heads—the resin glands containing most cannabinoids and terpenes—typically measure 50 to 120 micrometers in diameter, though ranges vary by cultivar and harvest maturity Strong evidence[1][2]. A 159 µm screen therefore captures the largest intact heads plus small clusters still attached together, above the threshold where most individual resin heads fall through. The screen size is chosen to separate coarser plant debris and larger contaminants from usable resin without losing significant trichome material to the above-screen waste.
What 159 micron does
- Filters out plant fragments, leaf debris, and contaminants larger than the mesh opening.
- Retains the largest intact and clustered trichome heads for the upper tier of a hash stack.
- Defines a size boundary: material that passes through a 159 µm screen but is retained by finer screens (e.g. 73 µm) sits in a size window associated with premium resin in solventless production Weak / limited[3].
- Works as a practical separation tool when stacked with other screens in a multi-bag washing system Weak / limited[3].
What 159 micron doesn't do
- It does not guarantee full-melt or premium quality. Melt texture and potency depend on trichome maturity at harvest, whether starting material was fresh-frozen or dried, washing temperature, agitation intensity, and drying protocol—not screen size alone.
- It does not make hash more potent than material caught by a different screen. Cannabinoid content is determined by what resin is present in the heads, not which bag filtered them.
- It is not a legal or regulatory grade. Terms like "6-star" or "full-melt" are descriptive conventions in the community based on visual appearance and melt behaviour, not screen-size standards Anecdote.
- It is not the only useful screen size. Smaller screens (90, 73, 45 µm) capture finer, often cleaner resin; larger screens catch less-desirable material. Choice depends on starting material and desired product.
Role in bubble hash production
The 159 µm screen typically occupies the top tier of a multi-bag stack used in bubble hash production. Water and fine resin pass through it; larger debris is retained. The material that passes through 159 µm but is caught by a 73 µm screen below is often considered desirable for hash rosin pressing or solventless concentrate production, because it combines reasonable purity with intact trichome heads. However, the quality of the final product depends on the whole extraction and post-processing workflow: freezing technique, wash temperature, bag order, drying, and water activity management all play critical roles Weak / limited[3].
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
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