The Difference Between Solvent, Solventless,
and Solvent-Free Extractions
CBD manufacturing requires separating the cannabinoids, terpenes, and flavonoids from the hemp plant using a process called extraction. Extraction concentrates these compounds into an oil whereby they can be formulated into elixirs, tinctures, pain creams, and more. All of the three extraction methods–solvent extraction, solventless extraction, and solvent-free extraction–are used to achieve the same goal: to produce a purified crude oil that can be formulated into many types of products. Here’s the rundown on how each method works.
This method uses a hydrocarbon solvent, such as ethanol, butane, or propane, that doesn’t destroy the plant compounds, but exposes the plant’s resin glands, the part of the plant where cannabinoids and terpenes grow. Examples of solvent extracts include the following:
Butane Hash Oil (BHO) uses n-butane as its primary solvent to strip the plant of its cannabinoids, terpenes, and other compounds. Wax, Budder, and Crumble are also concentrates made from butane extraction. The consistencies of the resulting oils range from formless and tacky to yellow and brittle to darkening yellow with a crumbly consistency.
Propane and butane both have a low boiling point, so they don’t require high temperatures or high pressure to extract compounds, and these solvents won’t disturb the cannabinoids’ and terpenes’ delicate structure. But because butane and propane are extremely flammable, extraction methods, including BHO production, are extremely dangerous.
Ethanol has the lowest toxicity level of any of the alcohols, which is why it is so often used in consumer goods. It is also second to water as the most commonly used solvent and is frequently used in CBD extraction. The method is simple: the plant is soaked in ethanol and then filtered to separate plant parts from the solvent and plant compound solution, leaving just the crude extract.
Once extracted, the remaining plant matter is removed and this crude extract oil containing high concentrations of cannabinoids and terpenes remains. However, the solvent must be purged from the oil before further processing can take place. Because it is impossible to remove the solvent completely, some residual solvent will remain. Ethanol, however, demands the least amount of purging.
CO2 extraction is a safer and healthier alternative to making hash oil, as it uses carbon dioxide. Also known as supercritical fluid extraction, this method is a chemical extraction that uses CO2 to remove the plant’s resin and is considered a natural solvent with a low carbon footprint. The method includes freezing CO2 gas and compressing it into a cold liquid. It’s then filtered through the plant, removing the resin, cannabinoids, and terpenes, after which pressure is applied to the CO2 liquid, returning it to its gaseous state. Once the CO2 evaporates, what remains is the extracted oil without any residual solvents.
This method uses no solvents to extract the cannabinoids and terpenes from the flower. Because the end product never includes solvents of any kind in its production, these concentrates are the most organic of any extract.
Rosin is one example of a solventless extraction that is made by applying high temperature and intense pressure to the hemp plant’s cured and dried flowers to produce a thick, sticky product that is not only solventless but also yields the highest concentration of cannabinoids and terpenes of all extraction methods.
Hash is another extract that doesn’t use solvents. For instance, water and ice can be used to make a high-THC concentrate called Bubble Hash, made by using fine micron bags, known as bubble bags, and immersing the cannabis flower in ice-chilled water and shaking it to separate the plant material.
Dry-sift kief is made by separating the sticky ends of the plant that cover the leaves and flowers, known as trichomes, from the other plant parts. Using a fine micron screen, the dried buds are rubbed across the screen to separate the plant parts, after which only a pile of trichomes are left, known as kief or THC crystals.
Not to be confused with solventless extracts that never use solvents during extraction, solvent-free extracts do use solvents; however, the solvents are completely removed from the extract and are not present in the final product.
Distillate is an example of a solvent-free extract and is accomplished through a method called short-path distillation also known as fractional distillation. The short-path method stirs the crude oil as it’s heated to separate plant compounds. The heat converts the compounds into vapor, which rises and is then run through a condensing coil that cools it back into a liquid. Different cannabis oil compounds vaporize at different temperatures, so as the heat increases, cannabinoids, terpenes, and other compounds vaporize and recondense at their own rate and are separated into individual flasks. Once crude cannabis oil, it is purified by means of winterization and decarboxylation.
Winterization uses a CO2 extractor to remove unwanted compounds by dissolving crude CBD oil in 200 proof alcohol to thin out the oil, then mixing it thoroughly, and immediately chilling it to -20 degrees Celsius. The plant compounds remain in the solution, while the fats, waxes, and other unwanted compounds freeze, coagulate, and rise to the top of the solution where the filters can easily remove them. Once through a CO2 extractor, the unwanted compounds and used filters are disposed of and the filtered oil is passed through again until it is thoroughly clean.
Decarboxylation removes a carboxyl group from a molecule, a change that causes inactive compounds to become active. Here’s how it works: Before phytocannabinoids are decarbed, they exist as acids. For instance, in live marijuana and hemp plants, tetrahydrocannabinol (THC) begins as tetrahydrocannabinolic acid (THCa), and cannabidiol (CBD) begins as cannabidiolic acid (CBDa), respectively. In their acidic (a) states, phytocannabinoids don’t provide any effects nor offer any benefits. However, once harvested, the plant is allowed to dry and the phytocannabinoids begin to lose their acidity. This process is hastened by decarboxylation, which heats the plant, changing the phytocannabinoids to THC and CBD. Heating removes the carbon dioxide molecule, causing the phytocannabinoids to activate and enabling them to provide the effects and benefits for which they are celebrated. This is why raw marijuana is smoked rather than eaten. Heating improves results.
The extraction method a company chooses is important to establish a successful foundation by which it can create superior formulations. More than ever, consumers are making healthier choices and looking for products that are pure and cleanly manufactured.