90u or 120u: which micron to choose for CBD hash?

Read "90u" as 90 microns, that is 90 thousandths of a millimetre: the size of the openings in the bag or sieve where the fraction was collected. The 120u lexicon entry has the reference definition, and the hash micron tool places each mesh on the 25 to 220 µm scale.

The number records how a fraction was sorted and says nothing of what it contains. Both main methods use it. In ice-water separation, called ice-o-lator, a suspension of trichomes runs through a stack of filter bags. In dry sift, dry resin powder goes through stacked sieves. In both cases each mesh keeps whatever is too large to pass and lets the rest drop to the next one.

A "90u" fraction therefore contains particles too big to pass 90 microns, yet small enough to have cleared the mesh above, which is often 120.

Trichomes are the tiny glands covering the female hemp flower. According to a paper published in 2020 in Scientific Reports, cannabinoids and terpenes are produced and stored in their secretory cells. Hash consists of these heads once they are separated from the plant.

Zamir Punja's team at Simon Fraser University in Canada measured their size on two varieties, followed from the 3rd to the 8th week of flowering. Published in the Journal of Cannabis Research in 2023, the results provide three reference points:

• capitate trichomes, which carry most of the resin, have heads 40 to 110 microns across;
• the much smaller bulbous trichomes have heads of 15 to 30 microns;
• as they mature, the heads turn brown and end up falling off their stalks.

These measurements concern two high-THC varieties. Genetics and harvest stage both affect head size, and nothing suggests that CBD hemp varieties fall outside this range.

An ice-water wash yields several fractions, and a common kit has eight bags. The manufacturer The Press Club explains what each one does; the last column of the table compares these meshes with the 2023 measurements.

Labels leave out what the diagram makes plain: a 120-micron mesh is wider than every head measured in 2023. It retains heads still attached to a bit of stalk, resin clumps and some plant matter. The 90 mesh retains loose heads of 90 to 110 microns as well. In practice the split is less tidy, because heads are not round and those still on a stalk behave like bigger particles. A finer mesh is no guarantee of a better fraction either: below 45 microns, partial heads, broken stalks and dust take over.

The catalogue has two products that can be compared. The figures below are the ones the product pages showed on 23 September 2026, given as reference profiles; as of 18 October 2026, no laboratory certificate has been published for these batches.

The 120u shows 0.8 points more CBD than the 90u, at the same price on every tier. A third product points the same way: the ice-o-lator 45u, batch PG-26-1E4E, shows 14.8%. Of these three batches, the one from the finest mesh has the lowest content.

The mesh is only one cause of these gaps. The two names point to two different methods, and the descriptions mention only a resin "separated cold, then pressed by hand". Nothing indicates that the batches share a variety, and the next batch could reverse the order. Our comparison of ice-o-lator 45u, 120u and Caramelo reads three ice-water products in the same way.

The number never tells you four things.

• Content: Hash CBG 90µ comes from the same mesh as the Drysift 90u, yet CBG dominates it, at 19.3% with 4.2% CBD (batch PG-26-83EF). The mesh is shared; the main cannabinoid differs.
• Melt grade: Full melt means a hash that melts without residue when heated. The extractor judges it by observation, and no laboratory awards it.
• The exact labelling, which follows no standard. As the lexicon notes, a "120u" jar may contain one mesh or two adjacent ones, for example "90u-120u".
• Compliance: the 0.30% Δ⁹-THC limit comes from the French order of 30 December 2021, which applies it to hemp extracts and the products containing them. Whatever the mesh, only the batch analysis checks it. Our article on whether CBD hash is legal sets out the rules.

The micron figure still hints at the method, since a producer who states it is telling you how the resin was sorted. Three checks matter more when you choose.

1. The dominant cannabinoid and its measured value on the batch on sale, not in the product name.
2. The Δ⁹-THC, stated as a figure and no higher than 0.30%.
3. A batch number that matches on the product page and on the label.

Aroma comes after that, and it follows the variety more than the mesh: of the two batches compared here, one is peppery and the other floral. For a resin that melts without residue, look for a stated full melt grade, which extractors obtain most often on the 73 to 90 micron meshes. You can learn to read an analysis on our laboratory page, and the CBD resins and hash category lists the products. To compare the methods themselves, see our comparison of static, frozen, piatella and 120u.