CBD rosin: a solventless extract, pressed with heat

In English, rosin first means colophony, a solid pine resin rubbed on bow hair and used in soldering flux. Cannabis rosin shares only the name: it contains cannabinoids and terpenes, while pine rosin is made of resin acids such as abietic acid. Some French-language pages translate cannabis rosin as "colophane", the French word for pine rosin: a false friend.

The Académie française defines colophane as the solid residue left by distilling turpentine. Its glycerol esters form the food additive E 445, re-evaluated by EFSA in 2018 and again in 2023.

The two meanings meet in adulteration. In 2006, Italian chemists found colophony in 1 of the 16 seized hashish samples they analysed. In 2020, a "thickener" for cannabis extracts turned out to be made mostly of pine rosin, with MCT oil and oleamide. In 2021, FDA chemists found pine rosin acids among the additives of about 300 cannabis vaping liquids. Yet pine rosin fumes are a recognised cause of occupational asthma in soldering, and a cannabinoid profile does not look for these acids.

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

The principle is simple. The starting material is placed in a filter bag between two heated plates and squeezed. Softened, the resin passes through the filter and is collected on baking paper. The fibres and debris left in the filter are thrown away.

This resin comes from the trichomes. A study published in 2020 in Scientific Reports points out that cannabinoids and terpenes are produced and stored in the secretory cells of these glands, which are densest at the top of female flowers. These structures are described in our article on trichomes.

The rosin press spread on the American cannabis market from 2015 onwards, carried by social media. Research has done little to follow.

A 2018 study counted 8,389 messages about rosin posted on Twitter between March 2015 and April 2017: among the original messages analysed, 44.2% came from media outlets promoting the technique. Its authors note that rosin is advertised as safer and more natural, yet remains a very potent cannabis concentrate. A 2021 review finds that solventless methods, the rosin press included, get little coverage in the literature.

Every rosin comes out of a heated press; what changes is the material put into it. BHO and live resin, on the other hand, are extracted with solvent. The word "live" tells you about the starting plant, frozen fresh, and says nothing about the process.

"Hash rosin" and "rosin hash" name the same product, pressed from hash. The finest ice-o-lator grades, called full melt, melt almost entirely. The separation methods are described in our article on homemade CBD hash.

In market usage, live rosin is pressed from frozen hash; no scientific publication defines these terms. See also our guide to live resin.

A press works on four parameters: plate temperature, pressure, time and filter fineness. Only the chemistry of heat has been measured, and it sets the trade-off: heat just enough for the resin to flow. The settings that circulate, in degrees and bars, nearly all come from equipment makers, and we do not repeat them.

In 2016, a study published 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 turned into 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.

For rosin, the most useful result is another one. The authors observed that the combined concentration of CBDA and CBD fell as time and temperature rose. Heat therefore converts the acid form into the neutral form and also destroys part of it. CBGA lost even more, whereas THCA conversion stayed almost complete. See our article on decarboxylation and our decarboxylation calculator.

For the other three parameters, we found no published measurement. Pressure pushes the resin through the filter, time trades yield against heat, and the filter holds back the debris; its mesh is counted in microns, to be set against the trichome heads of 40 to 110 µm measured in 2023. Our hash micron tool and the 120u entry of the glossary explain these meshes.

Heat also has a regulatory consequence: by decarboxylating THCA, the press produces Δ⁹-THC, the molecule capped at 0.30% in hemp extracts. A rosin can therefore leave the press with more Δ⁹-THC than the Δ⁹-THC line of its starting material showed. The ANSM, the French medicines agency, for its part excludes THCA from the list of narcotics only "subject to compliance with the content set in Article 1 of the order of 30 December 2021" (decision of 3 June 2024).

Terpenes give rosin its smell, and they are lost well below their boiling point, which ranges from 156 °C for α-pinene to over 250 °C for β-caryophyllene.

A boiling point is not an evaporation threshold. In a study published in 2020 in Frontiers in Plant Science, terpenoids in stored flowers had lost more than 50% in four months, in the dark, between 25 °C and −80 °C. Cannabinoids lost 26% on average over a year.

This has two consequences for rosin. The starting material must be recent and well stored, or the extract will smell flat. The extract itself is best kept cold and away from air, as our article on storing rosin and crumble explains. For hot use, equipment and temperatures are covered in our guide to CBD dabbing.

An extract made with a solvent must prove that none is left. To our knowledge, no French or European limit targets hemp extracts specifically. The reference framework available is pharmaceutical: the ICH Q3C guideline on residual solvents.

The ICH Q3C tables mention neither butane nor propane, which other rules, specific to cannabis in some countries, regulate. A certificate for a solvent extract therefore needs a "residual solvents" section. Our article can CBD hash contain solvents? shows how to read it. For rosin that line is irrelevant, though the rest of the analysis still counts: cannabinoids, heavy metals, pesticides.

It guarantees one thing only: no extraction solvent was used, so no solvent residue is expected. It says nothing about THC, which the press concentrates along with CBD, nor about pesticides in the starting material, nor about anything added after pressing.

Our article on wax and concentrates explains this effect, and our THC rate checker compares a rate with the threshold. Heat adds to it the Δ⁹-THC formed from THCA.

A 2015 study of 57 concentrates from the California medical market found over 80% of them contaminated with residual solvents or pesticides. All the pesticides were in the 48 solvent extracts, none in the 9 dry or water hashes. Nine samples do not allow a generalisation, and the process says nothing about contaminants in the starting material: only the batch analysis measures them, as our comparison of concentrate certificates and our article on heavy metals point out.

The label proves nothing on its own. In June 2025, the ANSM and Anses, the French health agencies, reported several hundred poisonings recorded since early 2024 and linked to products presented as CBD, mostly due to synthetic cannabinoids or THC above 0.3%. Finally, France's Conseil d'État points out that the 0.30% Δ⁹-THC rate "is not a safety threshold" (decision of 29 December 2022, point 19).

On a rosin's certificate, read four lines: the batch number, Δ⁹-THC, the CBDA and CBD pair, and terpenes if they were measured. If the seller claims "solventless", also look for the declared method. The ratio between CBDA and CBD reflects the heat received: the stronger the heat, the more the neutral form dominates.

A "total" THC adds 0.877 times the THCA to the Δ⁹-THC, the ratio of the molar masses of Δ⁹-THC and THCA (314.5 and 358.5 g/mol, PubChem). Our guide to the certificate of analysis covers each section.

This checklist applies to any product, including those in the resins, hash and pollens category: a product name replaces neither the declared method nor the certificate.

To our knowledge, no French or European text requires a residual solvent analysis for rosin. An attached analysis should name each solvent and its limit of quantification: "not detected" means "below that limit".

Rosin names a process rather than a substance: its status depends on the plant pressed. Made from THC-rich cannabis, it remains a narcotic. Made from an authorised hemp variety, it must show no more than 0.30% Δ⁹-THC.

The order of 30 December 2021 authorises only varieties listed in the EU or French catalogue whose Δ⁹-THC is not above 0.30%, and applies the same cap to hemp extracts and to the products containing them (Article 1, I and III). The Conseil d'État takes those extracts to mean "oils or isolates extracted from the hemp plant" (decision of 29 December 2022, point 17): to our knowledge, no text or ruling says whether rosin is one of them. The 0.3% of Regulation (EU) 2021/2115 is a condition for farm aid: hemp areas count as eligible only if the varieties grown do not exceed that rate (Article 4, paragraph 4).

Pressed from THC-rich cannabis, a rosin is one of the products "obtained from cannabis, its plant or its resin", whose production, possession and transfer, among other operations, are banned by Article R5132-86 of the French Public Health Code.

Press articles in 2024 presented rosin as a new drug. Yet the OFDT, the French drugs observatory, notes that THC-concentrated extracts inspired by North American markets are "much less frequently observed" in France than herb and resin, and seized resin already contained 29.6% THC on average in 2024 (February 2026 note). For any question, Drogues Info Service answers on 0 800 23 13 13, free and anonymous. In an emergency, call 15 or 112; deaf or hard-of-hearing people can reach 114 by text message, app or internet.

See also the legal THC rate in France and CBD hash and French law.