How micron screens sort cannabis trichomes, what a grade like 120–90 µm or 90–45 µm actually describes, how dry-sift and ice-water grades differ, and how to specify micron grades in a resin contract.
Micron grades are among the first numbers a buyer sees on a resin specification, and among the most misunderstood. "120 µm" or "45 µm" does not describe potency or purity directly. It describes the size of the openings in the screen used to separate trichomes from plant material. Understanding what that implies helps you compare offers, specify what you want and read a COA in context.
This guide explains what micron screens do, what a grade like 120–90 µm actually contains, how dry sifting and ice-water extraction express grades differently, and how to put micron grades into a contract.
A micrometre (µm), usually called a micron, is one thousandth of a millimetre. A 120 µm screen has openings of 0.12 mm; a 45 µm screen, 0.045 mm. The trichome heads that carry most of a cannabis plant's cannabinoids and aromatic compounds are microscopic, so separating them from the plant means working at exactly this scale.
A screen does one thing: particles smaller than the opening pass through, and larger particles are held back. Stack several screens from coarse to fine and you sort the material into size fractions. Each fraction is defined by two numbers: the screen it passed through and the screen that retained it.
Plant material doesn't break into neat pieces. When biomass is agitated, whether in a rotating drum, on a vibrating sieve or in ice water, the trichome heads break off, but so do stalks, fragments of plant tissue and fine dust. These particles come in many sizes, and they overlap with the sizes of the trichome heads.
Micron screening is therefore a trade-off:
No single fraction is "best" in every case. The plant material, how it was dried or frozen, how hard it was agitated and how the fractions were handled afterwards all shape the result. That is why cannabinoid content is a property of the batch, not the grade, and why a COA for the specific batch matters more than the micron number alone.
Different products use different screen ranges, chosen for the process:
| Product | Process | Micron range |
|---|---|---|
| Dry Resin | Dry sifting in rotating drums, then pressing | 120–90 µm |
| Powder Resin | Vibrating sieve tables and pollinators; sold by single grade or mixed | 120–45 µm |
| Frozen Resin | Cold dry sifting after 48 hours at −20 °C | 90–45 µm |
| Fresh Frozen Resin | Ice-water washing, collected in micron bags | 220–25 µm |
Two points stand out. First, dry resin uses a narrow band (120–90 µm) to produce a full-spectrum kief that is then dried and pressed. Second, powder resin keeps the fractions apart, so a buyer can order one specific grade rather than a blend, or a defined mixed grade.
The numbers mean slightly different things depending on the process.
Dry sifting. Screens are stretched over frames, drums or sieve tables. Material moves across them dry, and each screen separates what passes from what is retained. Grades are usually given as a range between two screens, such as 120–90 µm or 90–45 µm.
Ice-water extraction. Frozen material is agitated in ice-cold water, which makes the trichome heads brittle so they break off. The water is then filtered through a stack of micron bags, from coarse to fine. Each bag keeps the particles larger than its mesh, so ice-water grades are often named after the bag that retained them. In our fresh frozen process, the bags run from 220 down to 25 µm. The coarsest bags mostly catch plant debris, and the finer bags collect the resin fractions.
When you compare offers, check which convention a supplier uses. "90 µm" on a dry-sift specification (a range ending at 90) and "90 µm" on an ice-water specification (material retained in the 90 µm bag) are not necessarily the same fraction.
Screens sort by size alone, so some fine plant dust inevitably ends up in the same fraction as trichome heads of similar size. This is why some producers refine sifted resin further. Our Static Resin is dry-sifted resin refined again in a clean room with electrostatic systems, the Ecoseparator drum and the Plasmastatic table. They separate by a different property than size, lifting mature resin heads and leaving plant dust and immature trichomes behind.
If purity is your priority, a refined grade may suit you better than a narrower screen range. If you plan to refine or press material yourself, a raw single grade gives you more control.
Micron numbers make offers look more comparable than they are. Two lots both described as "90–45 µm" can differ widely if one came from carefully dried, hand-cleaned material and the other from biomass with more leaf and stem, or if one was sifted cold and the other at room temperature. The screen range tells you the size band; it doesn't tell you what else is in that band.
When you line up offers side by side, ask each supplier the same questions:
The answers usually explain more about the product than the micron number does, and a supplier who can answer all five clearly is one whose process is documented.
A clear specification avoids disputes later. When micron size matters to you, agree the following in writing:
Pricing, available grades and specifications for current batches are in the buyer portal. Apply for trade access, or use the Request a COA button on any product page.
It refers to the opening of a micron screen: 120 micrometres, or 0.12 mm. A range such as 120–90 µm describes the fraction that passed through the 120 µm screen and was retained on the 90 µm screen.
No. A finer screen collects smaller particles, which can include small or immature trichome heads and fine plant dust. Which fraction suits you depends on your process and specification, and cannabinoid content should be checked on the certificate of analysis for each batch.
Yes. Our Powder Resin is sold by single micron grade or as a mixed grade, from screens between 120 and 45 µm.
Ice-water extraction collects trichomes in a series of filter bags. The coarsest bag catches the largest particles and the finest bag the smallest, so the full set of bags spans a wider range than a dry-sifting line.