CBD rosin: a solventless extract, pressed with heat

A review published in 2025 in Frontiers in Toxicology defines rosin as a solventless extract obtained by mechanical compression, using heat and pressure. It sets it against butane hash oil, or BHO, produced by hydrocarbon extraction. The same review notes that terpenes are the second largest class of compounds in concentrates, after cannabinoids.

The principle fits in a sentence. The starting material goes into a filter bag between two heated plates and is squeezed. The softened resin passes through the filter and is collected on baking paper. What stays in the filter, fibres and debris, is thrown away.

That resin comes from the trichomes. A study published in 2020 in Scientific Reports notes that cannabinoids and terpenes are produced and stored in the secretory cells of these glands, which are densest at the top of female flowers. Our article on trichomes describes these structures.

Rosin does not replace hash: it often comes from it. Three materials can be pressed.

• Dried flower. The most direct route, with no sieving step.
• Dry sift. The trichomes were first separated dry on sieves. The press works on an already concentrated powder.
• Ice water hash. The ice-o-lator method separates trichomes in cold water. The finest grades, called full melt, melt almost completely with heat.

Pressing a material that has already been sieved leaves less plant debris in the extract, at the cost of an extra step upstream. Our article on homemade CBD hash describes both separation methods.

The word "live" tells you about the plant, not the process. In market usage, "live resin" is a solvent extract made from freshly frozen plants, and "live rosin" is its pressed counterpart, made from fresh-plant hash. No scientific publication defines these terms. Our guide to live resin explains how they are used.

The press settings that circulate, in degrees and bars, nearly all come from equipment makers. We do not repeat them. The chemistry of heat, however, has been measured.

A study published in 2016 in Cannabis and Cannabinoid Research heated extracts of Cannabis sativa flowers at five temperatures, from 80 to 145 °C, for up to 60 minutes. THCA converted to THC in about 30 minutes at 110 °C, 9 minutes at 130 °C and 6 minutes at 145 °C. CBDA and CBGA reacted about half as fast as THCA.

The most useful result for rosin lies elsewhere. The authors observed that the combined concentration of CBDA and CBD fell as time and temperature rose. In other words, heat does not just turn the acid form into the neutral form: it destroys part of it. CBGA lost even more. For THCA, conversion stayed almost complete.

The rule that follows is simple: press as cool and as briefly as possible while the resin still flows. That is what makes the process demanding. Our article on decarboxylation covers the chemistry in detail.

Terpenes give rosin its smell. They are also the molecules that go first. In a study published in 2020 in Frontiers in Plant Science, terpenoids in stored flowers had lost more than 50% in four months, while cannabinoids lost 26% on average in a year.

Two consequences for rosin. The starting material must be recent and well stored, or the extract will smell flat. And the extract itself must be kept cold and away from air, as our article on storing rosin and crumble explains. For hot use, our guide to CBD dabbing covers equipment and temperatures.

An extract made with a solvent has to prove that none is left. As far as we know, there is no French or European limit specific to hemp extracts. The available reference framework is pharmaceutical: the ICH Q3C guideline on residual solvents.

Butane and propane do not appear in the ICH Q3C tables: other rules, specific to cannabis in some countries, cover them. For a solvent extract, the "residual solvents" section of the certificate of analysis is therefore essential. Our article can CBD hash contain solvents? shows how to read it. For rosin, that line does not apply, but the rest of the analysis still matters: cannabinoids, heavy metals, pesticides.

French law does not treat rosin differently from other extracts. The decree of 30 December 2021 caps the Δ⁹-THC content of hemp extracts and of products containing them at 0.30%. In theory, pressing concentrates all cannabinoids, THC included: an extract made from compliant material is not automatically compliant. Only the batch analysis tells you.

On the certificate, look at four lines: the batch number, Δ⁹-THC, the CBDA and CBD pair, and terpenes when they are measured. The ratio of CBDA to CBD reflects the heat received: the stronger it was, the more the neutral form dominates. Our guide to the certificate of analysis goes through each section.

In the catalogue, the Rosift product, presented as a CBG/CBD hash rosin, shows 18.4% CBG, 3.9% CBD and 0.1% Δ⁹-THC on batch PG-26-EF5C (product page checked on 23 September 2026). Other solventless resins are grouped in the resins, hash and pollens category.