In this chapter of The Ultimate Guide to Cannabis Extraction, we’ll explore the major methods of cannabinoid extraction. You’ll find the most common cannabis and hemp extraction methods, as well as the end-products each method is most suited to produce.
Some of the following extraction methods are relatively new, only innovated in the last few decades. Other methods are thousands of years old and have changed very little over the millennia.
Why so many different methods of extraction?
The cannabis plant is incredibly complex and produces almost +120 different cannabinoids, terpenes, and flavonoids. You can target each of those compounds with different extraction methods. Your method may vary based on your desired derivative, the scale you’re working at, and the quality of your end-product.
For example, if you’re a large MSO (multi-state operator) you should consider solvent-based extraction methods that favor large-scale extraction. The most common solvents used are ethanol, CO2, or hydrocarbons. Smaller “mom and pop” brands who want to make high-quality live resin in small connoisseur batches, on the other hand, could be better off considering a professional rosin press set up.
So which is the best extraction method for your hemp or cannabis extraction business? Well, it depends.
In the cannabinoid manufacturing industry, we can never say one solvent or extraction method is better than any other because it all depends on what you’re trying to make—your intended end-product.
So, a much better question to ask is: What are you trying to produce?
Are you intending to produce CBD isolate at scale? Or full-spectrum, strain-specific vape oil? Or solvent-less water hash?
Choosing an extraction method can feel overwhelming. Especially considering the cost of extraction equipment. So, you can start by doing your market research to find out which products are in demand and/or will soon be in demand. Once you know which end-products you want to make first, your decision will become much simpler. Different methods excel at different end-products. Starting at the end and working your way backwards ensures you’ll be able to produce exactly what you intended to.
And then there’s the market. What happens when the market shifts and your desired end-product changes? Therein lies the real dilemma. Consumer demand, and therefore your desired end-product, will definitely shift over time. If you consider how the market might move before investing in equipment, you’ll save money when it does. Easier said than done, of course, but it’s worth it to pay for resources that can help predict where the market might move. Even if it’s just your crystal ball.
(If you’re interested in current cannabis and hemp industry market trends and opportunities you may also want to read our Cannabis Extraction Industry Overview: Mid-2020 Report.)
To help you decide which extraction and refinement method will help you produce your desired end-product, let’s explore the most commonly used solvent-based and non-solvent cannabinoid extraction methods.
The widespread use of solvents to extract cannabinoid derivatives has been popular for many years in the contemporary cannabis and hemp industry. They’re popular for a good reason: they’re easy to scale, efficient at producing the desired end-product, and relatively safe as long as you’re in compliance with local, state, and federal laws and guidelines.
The following extraction methods represent the primary or first stage of all cannabis and hemp processing (following the primary steps of growing, harvesting, drying, curing etc.). After this first stage, most derivatives (e.g. crude oil) will go on to further stages of refinement. Others will end up as consumer-end products ready for the shelf (such as full-spectrum and live resin extracts).
Ethanol is a colorless, volatile, and flammable liquid. It’s the intoxicating agent in all liquor, beer, and wine, and is also used to dilute motor fuel. Ethanol has been used for botanical extraction for thousands of years, and there’s no reason to stop now and that’s one of the reasons why ethanol is still one of the most popular solvents for use in extracting precious cannabinoids such as CBD and THC from cannabis and hemp today. And not only is ethanol fairly easy and safe to use, but it also has a relatively quick learning curve, even for rookie extractors.
The biggest benefit of ethanol is that it’s incredibly versatile in what it can deliver. It’s great at extracting an enormous diversity of desired cannabis and hemp end-products. And, properly handled, it doesn’t leave any residual solvent in the final end-product, which is why it’s considered a ‘clean’ solvent.
Ethanol’s ability to produce a wide variety of cannabinoid derivatives makes it an ideal solvent for both small-scale cannabis ‘connoisseur’ processors (who may be targeting a wide array of full-spectrum cannabinoids and terpenes), and also for larger processors seeking to isolate specific cannabinoids at scale.
When directly compared to the other two most popular solvents used to extract cannabis—CO2 and hydrocarbons—the ethanol extraction process is generally safer and easier:
To understand why ethanol is such a versatile solvent, we’ll need to put on our chemist’s cap and take a look at how it extracts cannabis and hemp compounds on a molecular level.
Ethanol’s solubility or its “Like Dissolves Like” quality makes it highly efficient.
Understanding solubility (the ability of a particular substance to dissolve in another substance) and the mechanisms that underlie it, is perhaps the most crucial piece of information that defines the action of extracting cannabinoids with ethanol.
At a molecular level, there are generally two different categories of molecules, polar and nonpolar:
This is what we mean when we say “Like dissolves like”.
The most common nonpolar molecules we encounter are lipids and fats, like cooking and motor oils. The most common polar molecule we encounter is water.
Ethanol can be both polar and nonpolar. This makes it incredibly versatile, and therefore ideal for extracting a wide variety of cannabinoids and other compounds, like aromatic terpenes, from cannabis and hemp. Ethanol’s ability to extract a wide variety of compounds is great for “full-spectrum” derivatives.
Ethanol is in a uniquely good position to dissolve most slightly nonpolar and slightly polar molecules, which turns out to be a lot of different molecules in cannabis and hemp!
How does Ethanol Extraction work?
The target compounds (the molecules we are attempting to extract and separate from the rest) typically include cannabinoids like THC and CBD as well as terpenes. All of these compounds are fat-soluble. Which is ideal because ethanol dissolves fats quite well. So if you’re intending to make ingestible, full-spectrum, cannabinoid derivative end-products, ethanol’s ability to extract these compounds can be an advantage.
The polarity of ethanol can be slightly modulated/adjusted simply by changing its temperature. This makes it a very flexible extraction tool.
The colder the ethanol, the higher its affinity for fat-soluble compounds, and therefore the more efficient its extraction of cannabinoids and terpenes. And if extraction is performed with warm or room temperature ethanol, it will not only “pull” the cannabinoids, but also a wider spectrum of terpenes as well as other water-soluble compounds.
As flexible as it is, ethanol does have its limitations. If your goal is to isolate certain cannabinoids exclusively—to make either THC or CBD isolate for example—ethanol may not be your ideal solvent because it doesn’t target individual compounds very well. Make sure to know what you want your end-product to be before deciding if ethanol is right for you.
As flexible as it is, ethanol does have its limitations. If your goal is to produce connoisseur level “live” products – that emphasize the terpene content of the original plant – ethanol may not be your ideal solvent because it does not separate from terpenes allowing for their extraction very well. Make sure to know what you want your end-product to be before deciding if ethanol is right for you.
The Ethanol Extraction Process
The ethanol extraction process begins by soaking your biomass in chilled or room temperature ethanol to draw out the terpenes and/or cannabinoids. The resulting solution is then evaporated to remove any residual solvent using heat and vacuum, resulting in a crude extract. The crude concentrate may then be further distilled and refined to create a purified CBD, THC, or CBG distillate, in preparation to be isolated from the other cannabinoids by means of affinity chromatography.
The ethanol extraction process typically flows something like the following (for our purposes here, a Cold Temperature Ethanol Extraction process flow):
The Benefits of Ethanol Extraction
Ethanol is a great choice for high volume output, which makes it an appealing option if you’re manufacturing cannabinoids at scale in a large commercial operation. It’s considered (by most) to be the safest and most effective solvent for cannabis and hemp extraction. Due to ethanol’s versatility and ease of use, it’s in a uniquely favorable position for almost any type of botanical extraction. This is especially true for cannabis and hemp extraction because it:
Which products is ethanol extraction ideal for producing?
Ethanol extraction is ideal for producing almost any cannabinoid derivative. The first output of the initial stage of ethanol extraction is crude oil AKA “crude”—the major building block of nearly all cannabis and hemp derivatives. Nearly all other end-products start off as crude before being further refined and purified.
Ultimately, crude oil is transformed into vape cartridge oil, gel caps, edibles, tinctures, sublingual drops, and topicals..
Ethanol is also an ideal solvent for producing isolates at scale. Once the crude oil has been distilled to further refine its potency we may isolate the compounds (like CBD or THC for example) to a very high level of purity (98%+) through methods such as column or flash chromatography.
A versatile solvent indeed!
What is CO2 extraction?
CO2 (Carbon Dioxide) Extraction uses pressurized carbon dioxide (CO2) to pull CBD, THC, and other cannabinoids from cannabis and hemp. CO2 acts like a solvent at certain temperatures and pressures. It’s used to extract concentrates under high pressure and extremely low temperatures to isolate, preserve, and maintain the purity of the extracted oil. CO2 extraction requires sophisticated equipment and significantly more training than ethanol extraction, but when executed correctly the end-product is very pure, potent, and free of chlorophyll.
Is CO2 extraction safe?
CO2 is considered to be a safe method of extraction because the solvent is non-volatile. It is used for botanical extraction in other industries for purposes such as decaffeination of coffee and the production of essential oils from a myriad of plants. The resulting derivative extract is pure because no trace of the solvent is left behind. CO2 also protects fragile cannabis and hemp terpenes, by allowing cold separation. It’s very adjustable—the operator can select custom pressures and temperatures to achieve desired results. Best of all, CO2 is environmentally friendly.
What is Supercritical, Subcritical, and Mid-Critical CO2 extraction?
When discussing CO2 extraction you’ll often hear the terms supercritical, mid-critical, and subcritical used. However, supercritical is by far the most commonly used CO2 method to extract cannabinoid derivatives because it is safe and provides a pure end-product.
Supercritical extraction utilizes liquid CO2 and increases the temperature and pressure to the point where the CO2 reaches its Supercritical point and has both the properties of gas and liquid simultaneously. This state is ideal for cannabinoid extraction because it will dissolve the THC and CBD like a liquid, but is easily manipulated and completely fills the vessel similar to a gas.
Subcritical extraction means that the CO2 is utilized at low temperatures and low pressure. While subcritical extraction takes more time and produces less yield than supercritical extraction it retains the delicate terpenes and other desirable compounds. This makes subcritical extraction ideal for producing end-products that retain the “full-spectrum” of beneficial cannabis and/or hemp compounds. Conversely, if you were seeking to produce an isolate such as CBD, CBG, or THC isolate you should not choose subcritical extraction because it requires many additional steps to isolate your desired molecules.
Mid-critical is a general range of temperature and pressure that is situated in between subcritical and supercritical. Not used as often as supercritical, you can use it to combine supercritical and subcritical methods to produce full-spectrum CO2 cannabis extracts.
How does the CO2 extraction process work?
The CO2 extraction process begins by turning CO2 gas into a liquid. This is achieved by dropping the temperature below -69°F (-56.11°C) while simultaneously increasing pressure to over 75 pounds psi.
The next step involves raising the temperature using a heater and pressure past the point where the liquid becomes ‘supercritical’ so that the CO2 now has properties of a gas and liquid simultaneously. At this point it is ready to be introduced to cannabis or hemp plant material for extraction purposes.
The CO2 passes through the plant material dissolving the membranes of the trichomes and extracting terpenes and cannabinoids such as CBD and THC.
After extraction, the resulting solution is passed through a separator and the desired compounds (cannabinoids, terpenes, etc.) are separated out and collected.
The CO2 is then condensed and turned back into a liquid ready to be used again and again.
What equipment is needed for CO2 Extraction?
CO2 extraction is performed by a “closed-loop extractor.” Essentially, all CO2 extraction equipment has three chambers:
Chilled CO2 is pumped from the first chamber into the second chamber. The second chamber is where the supercritical transformation occurs. The supercritical CO2 then passes through hemp or cannabis biomass to extract the cannabinoids and terpenes. The resulting solution is then pumped into the third chamber where the CO2 changes phase back to a gas, leaving the precious cannabinoid extract at the bottom and the CO2 ready for reuse.
The Benefits of CO2 Extraction
CO2 extraction has many benefits that appeal to both consumers and extractors. One of the biggest is that it’s an environmentally friendly—or ‘green’— solvent. It leaves no nasty chemical residuals thereby creating a purer and healthier end product.
Which products is CO2 extraction ideal for producing?
Due to its ability to extract “full spectrum” cannabinoid derivatives, CO2 is ideal for producing full-spectrum cannabis distillates and their accompanying delicate terpenes which give each cannabis and hemp strain its unique flavor and scent profiles. CO2 is valued for its ability to preserve the unique but fragile terpenes that are so highly valued by cannabis connoisseurs.
By tweaking the ratios of pressure, temperature, and solvent, various cannabinoid derivatives can be extracted by trained extractors. As a result CO2-based products have become the go-to in the cannabis and hemp market for everything from edibles to isolates. CO2 is incredibly customizable and adaptable to the changing needs of the marketplace and ideal for both small startups and large MSOs.
One major benefit for start-up extractors is that hydrocarbon extraction equipment is usually less expensive to purchase than CO2 and ethanol equipment. Hydrocarbon extraction can deliver a potent end-product suitable for dabbing, but it may not be the best method for producing other cannabinoid derivatives such as CBD and THC isolates.
Hydrocarbons like propane and butane have been used for food extraction for over fifty years. In the right hands their ability to extract derivatives from cannabis and hemp to a high degree of purity is exceptional; up to 90% concentration of plant cannabinoids.
How does hydrocarbon extraction work?
Hydrocarbon extraction typically uses butane as the primary solvent, although other hydrocarbons such as propane and hexane may sometimes be used depending on the desired end-product.
Butane has a low boiling point of 30.2°F (-1°C) and is used as a liquified gas during extraction. This low temperature retains the integrity of temperature-sensitive terpenes and other delicate derivatives.
Propane is also used commonly for cannabinoid extraction. Its boiling point is even lower than butane at -43.6°F (-42°C). Often a blend of both hydrocarbons are used, because propane is adept at extracting additional compounds from the plant such as delicate terpenes and is less likely to leave residual hydrocarbons in the resulting solution.
The hydrocarbon extraction process
The hydrocarbon extraction process typically starts out with the release of cold liquid butane from the solvent tank into a column containing the hemp or cannabis biomass. This action dissolves the terpenes and cannabinoids (THC, CBD, and other minor cannabinoids) along with plant waxes and lipids.
The cannabinoid concentrate is then ready for further refining (depending on your desired end-product):
The concentrated cannabinoid solution then ends up in a collection vessel where the butane (or other hydrocarbon solvent) should be gassed off using heat and vacuum. Depending on the desired product, these final steps may include whipping and/or drying in a vacuum oven. The separated butane solvent is then collected to reuse in the next batch.
The Benefits of Hydrocarbon Extraction
The use of hydrocarbons for cannabinoid extraction is becoming increasingly popular. Not just due to the more affordable cost of hydrocarbon extraction equipment, but also for several other reasons:
Which products is hydrocarbon extraction ideal for producing?
Hydrocarbon is ideal for producing dabbable cannabinoid derivatives such as budder, butane hash oil (BHO), crumble, honeycomb, shatter, resin, and wax. But hydrocarbon derivatives are not just limited to just dabbables they may also be used in topicals, edibles, vape cartridges, tinctures, capsules, and much more.
Edible Oils: Extra virgin olive oil, coconut oil, butter, and other edible oils can be used to extract fat-soluble cannabinoids by gently heating decarboxylated cannabis flower directly in the edible oil. While this extraction method is popular with small-scale home extractors, the resulting oil has a much lower potency and a lower shelf-life than other extraction methods, so it is not recommended for large scale commercial extraction of cannabinoids. However, it is seen by some as a more natural alternative to chemical-based extraction methods.
Note, cannabis-infused vegetable oils are highly perishable and should therefore be consumed quickly or be stored in a cool, temperature-controlled, dark place. You may also use inert nitrogen to “back fill” the storage container to increase shelf life. This is a common process is often used in the wine industry to reduce wine oxidization.
The vegetable oil extraction process
Suitable for home extractors of CBD and THC, vegetable oil extraction begins with heating the raw plant material so that the cannabinoids are transformed into their more bioavailable versions, for example CBDA into CBD, and THCA into THC. This process is known as decarboxylation, or decarbing.
Typically the temperature recommended for decarboxylation is approximately 284°F/140°C for 30 minutes or 248°F/120°C for 60 minutes. However, this is a rough guide only because it will depend on your plant material and strain, as well as the quality of your oven.
Once this step is completed, plant material is added to the vegetable oil (coconut oil and olive oil are popular) and heated to 212°F/100°C for 1-2 hours. This allows the fat-loving decarboxylated cannabinoids to bind to the fatty molecules in the oil, resulting in cannabinoid extraction. The plant material is then filtered out, leaving the infused edible oil behind. The resulting solution is a mix of the vegetable oil, terpenes, waxes, and cannabinoids, etc. Unlike other forms of solvent-based extraction, the cannabinoids solution is not separated out from the solvent. Edible-oil infusions are a distinctly “unrefined” oil and suitable for those who don’t mind their CBD or THC oil tasting like cannabis.
This form of extraction is ideal for absolute beginners and home extractors who enjoy safely making their own cannabinoid derivative extracts without spending too much money on equipment. However, the end-product is not as potent as those derived from the more industrial extraction methods such as CO2, ethanol, or hydrocarbons.
A growing number of consumers are now seeking cannabinoid derivatives that are produced via a non-solvent or “solvent-less” method. This is because they are perceived as being safer to consume because they are derived using a more ‘natural’ method. Whether that is true or not remains a contentious topic of endless discussion within the industry.
Non-solvent or solvent-less separation is in fact, not technically “extraction” at all but actually “mechanical separation”. This means that the cannabinoid is not extracted from the plant material via a chemical process but separated from it through a physical force.
Ice water based separation (“cold water extraction”) is ideal for producing ice water hash a.k.a. bubble hash. This method is a very popular method for producing high quality hash without using any chemical solvents.
This method works by mechanically separating out cannabinoid-rich trichomes from the biomass by breaking them off using a combination of water and/or ice and an agitational force.
Note, that although this method is often called “water extraction” it is actually not technically “extraction” in the true use of the word. This is because the cannabinoids are not actually extracted from the biomass but separated.
Delta Separations recently innovated the Vortex Trichome Separator (VTS-50) which allows hash makers to wash the plant material as gently as needed by controlling the vortex speed. This flexibility is one of the keys to minimizing material maceration and unwanted plant particulates in your end product. The end result is a maximum separation of resin heads from the plant surface with negligent to non-existent plant-particulate contamination.
The trichomes then remain in the water as suspended, undissolved solids. Once this water and trichome slurry mix is separated from the remaining biomass itself, it is filtered and separated out. The resulting trichomes are then crafted into hash “patties” and dried to produce a high-quality hash end-product.
Ice water-based cannabinoid derivatives like bubble hash are ideal for dabbing and are arguably considered to be some of the highest-quality forms of cannabis concentrates available.
Cold pressed cannabis or hemp oil is just what it sounds like. Similar to cold pressed olive oil or any other plant extract, the plant material is cooled, placed under great pressure, and crushed to literally squeeze the cannabis or hemp oil out of the biomass.
The cold pressing process involves placing pre-cooled cannabis or hemp plant matter (flowers, leaves, seeds, and stems) under pressure to extract a usable oil that can be consumed on its own, or combined with other ingredients to create the desired end-product.
While cold pressing performed at lower temperatures maintains desirable terpenes, flavonoids, and cannabinoids, the yield from this method of extraction is quite low. Cold pressed cannabis and hemp oil is showing up in wellness products such as tinctures and topicals.
Rosin and live rosin extracts are cannabis derivatives made by exposing cannabis or hemp plant material to heat and pressure to literally “squeeze” the terpenes and cannabinoids out from the trichome glands of the flower.
Favored by cannabis and hemp connoisseurs alike, rosin’s popularity is due to the perceived purity of consuming a product which has never come into contact with any human-made chemicals. Rosin is typically made out of either trichome-rich flower, dry sift (kief), or low quality hash. “Live” rosin is made the same way but from plant material that has been frozen immediately after harvest to retain the “live” plant compounds.
Similar in technique to the cold pressed method above, a rosin press adds the use of heat and pressure to squeeze cannabis and hemp oil out of biomass. This is a popular solvent-less, small-scale extraction method because of its relative safety, fast learning curve, and low cost.
While rosin home enthusiasts may use a hair straightener, professional rosin extractors use a small hydraulic rosin press with a heat controller to manufacture larger quantities of rosin. Whichever method you choose, the basics of how a rosin press works are the same:
The quality of your chosen biomass and the temperature you use will play a big role in determining the yield and quality of your rosin extract. Speaking generally, the temperature range for a taffy-like rosin product is between 300-335℉ / 149-168℃. If you’re seeking a more rigid end-product (e.g. shatter) you’ll want to aim for between 250-300℉ / 121-149℃.
Kief is one of the oldest known cannabis extracts. Its history goes back thousands of years. Screens used for hand extraction have been found in archeological digs from 3,000 BCE. And the extraction method for kief is still very similar to the method that was used thousands of years ago.
Kief is made from the most cannabinoid-rich, tiny bulbous formations of sticky resin glands at the end of trichomes of the cannabis plant. The attraction here for consumers is that kief delivers a high potency of cannabinoids in a single hit. As the most natural, non-solvent extract from the cannabis or hemp flower its popularity is due to its purity, potency, and versatility of consumption. Kief can be rolled in a joint, sprinkled onto a bowl of cannabis, pressed into hash, added to butter and included in edibles such as cookies, or used to make moon rocks, buds or nugs that are covered in cannabis oil and then rolled in kief.
Once you have dried and cured your cannabis or hemp plant material, a grinder and/or dry sifter is used to produce kief. You may then want to press the resulting product into solid hash via the use of a hash or pollen press if so desired.
Most of the extraction methods mentioned above are typically included in the first stage of hemp and cannabis processing. After this initial stage, the raw product, often in the form of crude oil, may go on to be further refined in additional steps, to learn more about the cannabis extraction process read Chapter 3: Cannabis Extraction & Refinement Process Overview