After more than four years in the cannabis industry, I can absolutely fake my way through a conversation about extraction. I know some of the key terms, can name a few of the product types and then everything else boils down to repeating the last statement said to me with a semi-sarcastic shrug.
“Yeah, hydrocarbon, totally.”
As a staff writer for Marijuana Venture, I have largely reported on the retail side of the industry. Most of my interviews have been about store design, inventory management and retail operations. And I’ve been more than happy to leave the science stuff to other editors and writers, considering my education was largely in journalism and communications. I was past due for a crash course in the basics of extraction.
Special thanks to Christian Sweeney, the director of science and technology for Cannabistry Labs in Colorado, Seth Oxhandler, the chief science officer at High Five Edibles in New Mexico and AC Braddock, the CEO of Eden Labs in Washington, for donating their time — and more importantly, their patience — to help make this article possible.
An overview of common extraction solvents
Here’s an overview of the three main categories of solvents used for extracting cannabis, including some personal critiques on the terminology, safety and technical aspects or end results for each solvent.
Carbon dioxide (CO2) is what’s called a “tunable solvent,” meaning it can be set to a variety of temperatures and levels of pressure to create different products.
“Supercritical” is often used inaccurately as a synonym for CO2 extraction (ethanol can also be used for extraction in a supercritical state).
The science behind supercritical is ridiculous. Scientists heat and pressurize a solvent above its critical point, where it cannot take a liquid or gas form and yet can move through solids like a gas and dissolve in the same way a liquid could. Subcritical extraction functions along the same lines except the solvent is cooled and pressurized below its critical point.
CO2 extraction leaves very little solvent residue and any remaining carbon dioxide evaporates over time, making it a pretty solid option for creating medical products. Also, CO2 is great for making vape pens, because it can selectively pull terpenes without collecting waxes or lipids from plant material.
Hydrocarbon extraction needs some PR work. Hydrocarbon extraction uses butane or propane (hydrocarbons) to remove cannabinoids from terpenes.
At-home butane extraction is the cannabis equivalent of the stories about moonshiners going blind from making bathtub booze, albeit with a lot more death and explosions. Most of the explosions are the result of what is known as “open blasting,” a process that often involves tightly packing cannabis into a tube with a mesh screen at one end and a cylinder of flammable solvent at the other end and then collecting the extract being pushed through the mesh screen. That is, of course, if the slightest spark doesn’t ignite the entire apparatus and cause a fiery inferno.
Open-blasting butane and propane was one method that helped popularize extractions and cheap concentrates prior to the current, highly regulated stage of the industry. And home-lab explosions have been a black mark on the industry for years, giving prohibitionists a reason to say cannabis operations are inherently dangerous.
Open-blasting may be cheap and easy, but I’m sorry, there’s absolutely no argument for it that outweighs the possibility of injury or death.
However, hydrocarbon extraction can be done safely with a closed-loop system, in which a recovery tank completely seals the solvent from outside air, then separates and recycles the used solvent back through the system.
Hydrocarbon can be a fast, safe extraction process that can be described as an “easy to learn, difficult to master” way to make concentrates.
Although popular in many other industries, ethanol processing has seemingly been stuck in the shadow of other extraction methods when it comes to cannabis. When the solvent is introduced, it saturates and then pulls everything from the plant material.
One of the most common concerns about ethanol is that it can work a little too well, removing waxes and chlorophyll from plant materials along with the targeted terpenes and cannabinoids and therefore requiring slightly more time to refine the finished product.
The professionals I talked to said ethanol extraction works well for edibles because the taste of cannabis is removed when monoterpenes and sesterterpenes evaporate during refinement.
Alcohol does not leave any residual toxic solvents, making it a safe choice for medical products.
When I set out to research this article, I wanted to better understand the process and some of the misconceptions of extraction. I turned to the gatekeepers of the science, not to completely bridge the knowledge gap, but to find a better vantage point to peer over the fence and possibly shrug a few less times during conversations with processors.
It turns out there are a lot of people in the cannabis industry with misconceptions about extraction. Extraction is simply removing one thing from something else. It’s a technique that’s been widely used for ages in the food, beverage and pharmaceutical industries. With cannabis, it’s the process
of using temperature and pressure, often in combination with a solvent, to remove the trichomes, terpenes, cannabinoids and other components from the plant material.
A major tripping point for extraction laymen is confusing solvents (alcohol, butane, CO2, etc.) with extraction methods (closedloop, supercritical, open blasting) and sometimes even with refinement processes (short-path distillation, vacuum ovens).
I hoped there would be straightforward answers about the best techniques. From what I’ve gathered, there isn’t really a “best” medium for extraction. They all have their strengths and weaknesses. It really depends on the product you’re trying to make. Anyone trying to argue otherwise has an agenda.
My biggest takeaway is the importance of hiring really knowledgeable extraction technicians, both to manage the operation and to understand the finer points of the methods and machinery needed to create the desired products for your specific goals. Extraction is a dense and costly science. It’s
not exactly something you can pick up over a summer at community college. There’s a reason why many of the large extraction companies are headed by professionals with Ph.D.s in chemistry.
YOU GET WHAT YOU PAY FOR
Another point worth noting about extraction is the importance of safety (which also ties directly into the need for hiring well-qualified personnel).
The vast majority of legitimate cannabis companies are already observing best practices when it comes to extraction, but there’s always going to be some inherent danger when dealing with extreme pressure and temperature and highly flammable solvents.
Quality commercial extraction equipment isn’t cheap and neither are professional technicians. Extraction is just not the part of the operation where cutting corners will pay off.
“We’ve always done it this way,” isn’t a compelling argument when someone’s life is on the line.
If you’re getting into the extraction game, spend the money on quality equipment and a professional to run it.
One of the larger issues within the cannabis industry is that every company seems to want to specialize in everything. They want to handle every aspect of cultivation, extraction, product manufacturing and distribution. This might be fine for growing, packaging, logistics and retail, but extraction is one of the few facets of this industry that can result in injury or death if it’s mishandled.
For many companies, it might be better to focus on cultivation and work with a licensed third-party processor to handle the extraction. It’s better than being responsible for an employee’s death or injury from trying to save a few bucks. And it’s a way better option than going back to school to
learn all this science nonsense. So again, spend the money.
If you’ve ever seen a YouTube video of people mixing ice and cannabis together in a bucket, then you’re somewhat familiar to one of the most basic forms of extraction. This process freezes the trichomes off plant material for collection.
Some of the most popular solventless concentrates — dry-sifted kief, bubble hash, rosin, etc. — require a physical and direct approach to extracting the trichomes from cannabis. Technically, this can go back as far as trimmers collecting the trichomes from their hands after a harvest into a ball of “finger hash.” The majority of commercial cannabis businesses today have moved on to more technical approaches to processing, though many craft producers still prefer the timeless results of physical extraction.
Short-path distillation seems to be one of those phrases that people misuse. It’s not actually a form of extraction. I know, it sounds like it would be, right?
Short-path distillation is a refinement process. Basically, it’s taking the extracted cannabis oil and putting it under a deep vacuum and high heat to separate the cannabinoids from the unwanted materials that have a lower boiling point, vaporize off and condense into a separate flask.
To be honest, having done this article on extraction, I can say that I have a slightly better understanding of the processing side of the industry, but I still feel like I have more questions than answers. This is to be expected, considering I researched the subject through a few phone calls with leading experts, while true extraction professionals have spent years and years in college studying the science.
The depth of the science involved bolsters the idea that anyone setting up an extraction operation should thoroughly vet and hire an educated technician. There’s simply to much going on here to just plug in a machine and have at it. If you are going to fork over more than $100,000 for a system you should probably understand its capabilities, pros and cons.
But if it were my money, I’d look for a qualified third party to clock in and handle my harvested plant material. That way I could stay focused on cultivation. And any time somebody would want to talk in depth about extracts and concentrates, I could just keep shrugging and repeating their statements back to them.
“Yeah, hydrocarbon, totally.”