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Ever wonder how distillates are made? Despite how it's marketed, distillation isn't strictly an extraction method. Instead, it's considered post-extraction processing.
Long before a vape pen is filled with 99 percent pure THC or CBD, the raw plant material must go through several other steps to refine, filter, and purify. Only then does it get further distilled into the ultra-pure cannabinoids now flooding the market.
Before Distillation: Extraction, Winterization, Filtration, Decarboxylation
Before the distillation process can begin, cannabis has to go through several other steps. First, the raw plant material must go through a primary extraction. The most common methods used in the industry include butane, CO2, and ethanol.
Each method comes with its own set of pros and cons. For example, some methods help preserve terpenes, while others are easier and more affordable to scale.
Following the initial extraction, the cannabinoid concentration (called crude oil) reaches between 60 to 80 percent purity. However, it still contains several non-desirable compounds like plant waxes, chlorophyll, and lipids. Therefore, the second step of winterization and filtration is required, which helps remove these unneeded compounds.
Winterization, also called dewaxing, uses ethanol to remove these waxes and fats. While butane and other hydrocarbons are common for crude oil extraction, they are not suitable for distillate production as lingering lipids (fats) find their way into the oil.
Typically, low temperatures (even room temperatures) are used for winterization to solidify the fats and waxes. Then, following separation, it's time to filter out these layers (including the solvent) from the purified cannabinoids, terpenes, and remaining plant material.
A final, optional step, depending on the goal, is decarboxylation.
On to Distillation: Short Path Distillation
Once the crude oil has been extracted, winterized, and filtered, the final step is distillation. The two most common pieces of distillation equipment are a small-scale short path distillation and a wiped film variation for larger, continuous distillation. Both use similar chemistries.
Unlike straight extraction and winterization, distillation requires no additional chemicals, solvents, or materials except H20. Short path distillation relies on heating a flask to vaporize various cannabinoids and terpenes within it. Next, the vapor travels through a secondary component known as a condensing head, where the vapor liquefies for recollection.
Extractors manipulate temperature to target different cannabinoids and terpenes. Each has a unique boiling point, which allows for separation and collection. Several collection flasks are attached to the condenser, and as the temperature changes, the lab technician can capture specific final distillations.
Temperatures dictate the contents, color, and consistency collected into each final flask. These are called heads, mains, and tails, indicating the first, second, and third phases.
The mains are usually pale, golden yellow, and contain the purest cannabinoid. Heads and tails are still valuable, however not considered a premium extraction as they may still contain impurities other than the targeted cannabinoids.
The final contents of the heating flask will become darker and greener as the cannabinoids and heavier terpenes are removed during distillation.
Large Scale Distillation: Wiped Film Distillation
Wiped film distillation (also called wiped film evaporation) is used for large-scale, more continuous production of cannabinoid distillates. According to ExtraKLAB, one wiped film evaporator can process as many as 14 short-path distillation units.
But in essence, it relies on the same methodology:
- Heating crude oil to a specific temperature
- Vaporizing targeted cannabinoids
- Condensing these separated cannabinoids for collection
During wiped film distillation, the crude oil trickles down over a heated wall within the equipment, encouraging the use of rotating wipers. Once again, as it reaches specific temperatures, the target cannabinoids evaporate. While the terpenes and other less desirable components are separated, a condenser re-liquifies the cannabinoids for collection.
This technique makes it possible to hit 80 percent CBD or more than 90 percent THC in the final product. Once again, the entire process relies on the individual boiling points of the terpenes, cannabinoids, and other compounds in crude oil. For example, THC relative boiling point is 314.6 ˚F (157˚C), and CBDs is between (160-180˚C) 320-356˚F
THC and CBD Distillate, a Post-Extraction Process
Raw crude oil is the common denominator for all distillate products, but it doesn't matter whether it's obtained using CO2, ethanol, or hydrocarbon. Following winterization, filtration, and optionally decarboxylation, the purified crude oil is ready for distillation.
Technicians further refine the product to final incredible potencies using advanced laboratory equipment (either short path or wiped film). Through this advanced processing, in some cases, THC distillates can reach 90 percent THC or greater.
Because any grade of crude oil can go through the distillation process, it's an excellent way for producers to capitalize on lower-quality crude oils. With the growing demand for distillate products in vape pens, edibles, and other cannabis goodies, distillates production is an increasingly appealing post-production technology.