The average yield or return on concentrates (amount of product produced vs amount of cured material used) is 15%, though each extraction process will have different results as far as yield, efficiency, texture, and flavor of the final product. But for the 15% ratio, this means for every 1 0lbs of cured product that is processed, approximately 672g of hash is created. There are a number of ways sweet leaf trim, flower nugs, or whole plant material can be processed into hash, with the most common processing methods being Butane (BHO), Carbon Dioxide (CO) and Solventless extractions. Some are even taking the process further and distilling the cannabis oil in a process called Short Path Distillation.
Carbon dioxide (CO) is the most frequently used gas for extraction because its critical point can be reached at around 88 °F. At or above this temperature and at the correct pressure it becomes a supercritical fluid with properties between a gas and a liquid. It will expand like a gas to fill its container, but with a density like a liquid. It has been used as a solvent in extraction process for many industries from food extracts to perfumes to essential oils. In addition to being a tried and true process, it is also safer than the BHO process since CO2 is non-combustible. Since CO2 is non-toxic, it can also be used to make extracts for some edibles and topicals and is more friendly to the environment than other hydrocarbon gases.
In the cannabis extraction process, supercritical carbon dioxide runs through an extraction vessel at a specific temperature and pressure. After gathering the available terpenes, waxes and cannabinoids, the solution passes to a separator vessel with a different temperature and pressure setting that can be used to change the composition of the extract. After the extraction is complete, a drop in pressure allows the CO2 to easily evaporate and be recovered.
Butane Hash Oil, or BHO, is the essential oil from the cannabis plant, derived from hydrocarbon extraction, using a solvent like butane or propane to strip the essential oil from the plant matter. BHO extractions are made with the same principles as CO2 extractions, and are desired mostly because the yield has historically been higher than solventless extractions or those from carbon dioxide.
First, plant material is loaded into the extractor, then a hydrocarbon gas is pushed through the cannabis. A processor may use all butane or use a different combination of hydrocarbon gases for each extraction. As the mixture moves through the pumps it changes from a gas to a liquid through the application of heat and pressure.
Vacuum ovens are used in the final step of the extraction. The material that comes out of the BHO extraction machine is then transfered to an oven to slowly heat the mixture and purge remaianing solvents from the concentrate. Manipulating the mixture while it’s in the oven by adjusting temperature and baking time can result in different textures of concentrates. Closed Loop machines such as these below are used for both BHO and CO2 Extractions. Vacuum ovens provide decarboxylation, which is a chemical reaction that removes a carboxyl group and releases carbon dioxide. An example of a vacuum oven is shown below as well.
Short Path Distillation
One of the newest, and arguably the purest form of processing, is the short path distillation process. Once the oil has been created using either the CO2 or BHO method, the process is taken even further. First, a process called winterization uses an alcohol bath (generally ethanol) and subzero temperatures to freeze the oil, which results in separating much of the fat and wax from the essential oil. This substance is then filtered multiple times to remove impurities. In the last step, all traces of alcohol from the winterization process are removed and the oil is filtered again to get the cleanest product possible.
Using heat to vaporize the cannabinoids, the vapor is channeled into a cooling system turning it back into a liquid, and the cannabinoids are collected into beakers with a process called fractional or short path distillation. This allows the isolation of terpenes and cannabinoids in their purest form, as the plant matter and residual solvents are filtered out. What remains is a clear, clean concentrate that is viscous like honey or sap, containing nearly 100% cannabinoids. The fractionating process will make custom concentrates possible as it separates different compounds like terpenes, oils, and cannabinoids. They can then be re-combined in the lab to create more specific concentrates in terms of flavor profile or cannabinoid content.
Here is an example of short path distillation equipment.
Check out all of our current concentrates, the companies that process them, and its methods.