There are various techniques for separating resin from plant matter using mechanical methods, whether by shaking or heat and pressure. In addition, there is another method to carry out this extraction using solvents like butane gas, ethanol, and propanol, for example.
To put it simply, this dissolves the trichomes in the liquid solvent to filter the plant matter mixture. After that, the solvent will have to be purged with a vacuum oven or a bell jar and a vacuum pump to ensure minimal traces of solvent remain in the extraction.
Type of extraction with solvent
Below are the types of extractions and forms of concentrates obtained today:
Hydrocarbon extractions or BHO (Butane Honey Oil)
Undoubtedly one of the best-known extracts worldwide. The relatively low polarity of butane allows it not to extract chlorophyll or other water-soluble components. This results in a product that, if appropriately purged, contains almost no impurities.
Although butane extractions have been carried out for several years now, improvements in extraction equipment have allowed a notable increase in the quality of this type of concentrate.
They are now of higher purity and with much less solvent. It is, therefore, possible to find today a wide range of extractions produced.
The final texture depends on many factors: genetics, terpene profile, purging technique, or handling after extraction, among others.
PHO (Propane Honey Oil) extraction
Less popular than BHO, propane oil is done in a very similar way. It is an extraction with slightly different ratios of cannabinoids and waxes. Propane has a lower boiling point than butane, so purging it is easier without affecting the terpene content. Thus, PHO has a more viscous texture, which, as we have seen, is associated with extracts especially rich in terpenes.
Propane, however, is much more expensive than butane, so some professionals use a mixture to get the best efficiency.
Co2 is often used by professional laboratories for the high purity of the product obtained. This is because the solvent leaves the least residue in the extraction.
The disadvantage of this extraction method is the heavy economic investment required to equip the laboratory to perform this extraction. Also, there’s the loss of terpenes during the extraction process.
This is why most co2 oils produced are destined for cannabis edibles or tinctures. They are sometimes mixed with terpenes to be loaded into vaporizer cartridges or e-cigs, an increasingly popular method of consuming resin concentrates.
Cannabis resin naturally contains a series of neutral, non-active substances, such as waxes and lipids, which do not possess medicinal effects. In addition, these are thought (although more research is needed) to be related to some respiratory issues such as lipid pneumonia. This is why many people strive for the purest, wax-free extraction, especially those using inhaled medicinal cannabis.
Initially, a complicated process called “winterization” was performed, which involved using a second solvent of ethanol and cold filtering. Although this is a very effective process for removing waxes, many terpenes are also lost, losing both flavor and therapeutic potential.
Today the waxes are filtered during the extraction process, working with much lower temperatures. This allows the lipids to solidify so that they are almost entirely filtered.
In addition to removing waxes, this second technique preserves all the terpenes and produces a clean and tasty BHO.