Whether you go online or find marijuana concentrates, tinctures, and other weed-infused products in a dispensary, the items you see are made possible through the process of extraction. Companies use one of a variety of available techniques to separate the components of marijuana and remove them from the plant matrix.
These cannabis extraction techniques isolate specific compounds. In weed’s case, there are at least 113 known cannabinoids including THC (which causes a psychoactive effect), CBD (which does not), CBG, CBN, and a host of others. There are over 500 chemicals in the marijuana plant including terpenes; aromatic compounds that provide the unique scent and taste of different strains.
There are several methods of extracting cannabinoids and chemicals from the marijuana plant. While supercritical CO2 extraction, involving the use of carbon dioxide, is considered the gold standard, ethanol extraction is also extremely popular.
Ethanol & Its Guidelines in Extraction
If you have ever drunk grain alcohol, you have consumed ethanol. It is a volatile and colorless flammable liquid which acts as alcohol’s intoxicating agent, and it is also used in fuel and as a solvent. Ethanol can be fermented from several sources of starch such as barley, wheat, corn, and potatoes. Since the U.S. has a huge supply of corn, most of the ethanol made in this country is made from corn.
According to the Food and Drug Administration (FDA), ethanol is a Class 3 solvent with a low risk for chronic or acute toxicity in pharmaceutical manufacturing processes; as long as the residual quantity is less than 0.5%; or 5,000 ppm (parts per million). The FDA also says that residual solvents must be kept below this low level through strict quality control processes. In certain states, however, the maximum level of environmental exposure to ethanol is less than 0.1%.
The Ethanol Extraction Process
Ethanol is one of several solvents used in cannabis extraction. Butane and propane are also used, and while they are cheaper, they are more volatile and dangerous. When you use a solvent for extraction, the weed soaks in the solvent, and the plant material is removed. Next, the liquid gets filtered, and the alcohol is removed via evaporation.
One of the main challenges associated with solvents such as ethanol is its inherent polarity; a fancy term for saying it mixes with water and dissolves chlorophyll and other water-soluble molecules. Removing chlorophyll from a marijuana extract is important because otherwise, your end product will have a bitter and unpleasant flavor.
You can perform alcohol extraction at atmospheric pressure as long as the temperature is tightly controlled. The main issues here are that ethanol is flammable and dangerous, and the entire process takes time. On the plus side, you don’t need to worry about toxic residual chemicals in the final product; and you can extract cannabinoids, flavonoids, and terpenes.
Here is a step-by-step guide to the ethanol extraction process.
1 – Extract Unwanted Materials
Ethanol is the extraction method of choice for many companies because it doesn’t require high pressure like butane and CO2 which makes it safer. You also end up with a full-spectrum product. Ethanol extraction is especially sought after by creators of concentrates as their goal is to cram as much THC or CBD as they can into a gram of product.
When you use ethanol, you perform what is known as a ‘quick wash.’ You might wonder why companies don’t directly heat up the alcohol with the flower to extract the largest amount of terpenes and cannabinoids. We already touched on the answer above: Alcohol is a polar solvent which means it would extract alkaloids, chlorophyll or any other water-soluble substances.
Therefore, it is necessary to use dry plant material. You can do this at home by putting the flower in the oven at a temperature of around 190-200 degrees Fahrenheit. You’ll know the weed is ready if it crumbles when you press it between your fingers.
Through experimentation and research, companies now have a method of extraction that removes almost 100% of residual ethanol from the byproduct after extraction, bypasses chlorophyll and lipids, and doesn’t compromise the product’s terpene or cannabinoid profile. The leading extraction companies now test products with less than 180 ppm of residual ethanol, far below the FDA’s upper limit.
2 – Winterization
The process of winterization, sometimes called an ‘alcohol wash,’ is performed after the initial extraction procedure. It involves the removal of waxes, lipids, and fats from extracts. Incidentally, ethanol is used for this step if CO2 has been used for initial extraction. The raw extract is placed in ethanol, heated, and then frozen, to filter out what remains of the unwanted byproducts.
The ethanol solution is warmed to around 120 degrees Fahrenheit and is not frozen until the solvent is evaporated. Typically, the solution is frozen for a minimum of 24 hours at a temperature of at least -32 degrees Fahrenheit. Alternatively, you can freeze it at -13 degrees for 48 hours.
3 – Filtering
As you know, the goal is to create a solvent-free extract which is done via the process of distillation, also known as ‘purging.’ This is the evaporation of the ethanol which boils off at a temperature of approximately 173.4 degrees Fahrenheit. If you are able to pull a full vacuum, ethanol’s boiling point falls to just 55 degrees.
There is equipment such as vacuum distillation apparatus or a rotary evaporator on the market to remove or reclaim your ethanol.
DIY Ethanol Extraction
You can use pure ethanol to extract cannabinoids and terpenes at home because it shouldn’t contain any toxic substances. Don’t use isopropyl alcohol for this purpose because it contains far more toxic materials than ethanol. Make sure your plant material is extremely dry after heating it in the oven to decarboxylate it.
Place the dried plant matter into a freezer and do the same with the ethanol you’re going to use. Once the temperature is stable at approximately 0-2 degrees Fahrenheit, pour the alcohol into the jar until the plant material is covered by up to an inch of alcohol. Gently stir the mix to ensure the plant matter is soaked and place the container in the freezer again.
Wait for around 3 minutes and stir the mixture gently several more times. Next, pass it through a strainer to separate the plant material from the alcohol extract. You can do this a second time after first allowing the plant to dry.
There are several ways to filter the solution further. You can use lab and vacuum filters of around 40 microns, special resin drying screens of 25 microns, or pour everything through a coffee filter in a pinch. Use a Pyrex tray to collect the solution. Next, put the tray in a water-bath (a bain-marie is handy here) at a temperature of between 160 and 180 degrees Fahrenheit until you see no more large solvent bubbles.
Filter the material once again before placing it back in a water bath. Keep the container in the water until you see that there are extremely few small bubbles on the edge of the tray. If you want to avoid allowing suspended particles to fall into the mixture, cover the tray with a 25-micron drying screen. Place the extract in the water bath for a third time to conclude this part of the process.
It is ideal if you have a vacuum pump, heating plate, and a vacuum desiccator chamber to vacuum purge the extract. Collect your extract after the first water bath and put it on a non-stick surface. Adjust your heating plate to 100 degrees Fahrenheit and add the extract to the vacuum chamber.
Begin the vacuuming process using your equipment. When the pump begins operating, the extract will swell in size. When this happens, switch off the pump until the extract goes back to its normal size. Switch the pump back on and repeat the process until your sample doesn’t swell anymore. Finally, switch the vacuum on again and allow it to operate for 24 hours. Do the above correctly, and you will have successfully used ethanol extraction to create a marijuana concentrate.
Ethanol Extraction – An Evolution
Ethanol extraction has its challenges. Full-extract cannabis oil is known for being dark, thick, and filled with chlorophyll. Also, as ethanol has a higher boiling point than butane, it is harder and more expensive to recover the solvent itself. Companies such as Capna Fabrication in California are looking to change the face of ethanol extraction.
According to the firm’s VP, Noe Garcia, its Ethos-4 and Ethos-6 ethanol extraction systems are game-changing innovations. Garcia spoke about an accident in the Capna lab which involved butane. The incident forced the company to rethink its use of butane, but CO2 extraction had challenges such as reduced scalability and huge time investment.
In the end, the company settled on ethanol and developed a pair of systems to create high-quality marijuana extracts in a matter of minutes. Both systems are capable of producing extracts free from chlorophyll, as well as being winterized and de-waxed. Moreover, the cannabinoid yield is up to 82%, and the terpene yield is up to 7%. Both systems have a solvent recovery rate of 85%!
The Ethos-4 is the smaller of the two with a 24-gallon ethanol capacity. It is capable of processing 2,500 grams in just 30 minutes. The Ethos-6 has a 36-gallon capacity and processes 3,600 grams in 40 minutes while drawing just 15.8 amps of power. Garcia said the company was hoping to create a system that can process up to 50 pounds in an hour, and soon enough, the Atles was born.
This automatic system has a 165-gallon ethanol holding capacity and a material load capacity of over 20,000 grams! Overall, you are looking at an extraction throughput of 90 pounds per hour with a solvent recovery rate of 85%, and it can also yield up to 9% terpenes.
How Does Ethanol Compare to Other Extraction Methods?
When a popular cannabis-related publication asked a team of experts to look at CO2, hydrocarbon, and ethanol extraction methods, they attempted to compare the three in terms of cost, safety, quality of the final product, and efficiency. In case you were wondering, ‘hydrocarbon’ extraction involves the use of propane and butane.
Overall, hydrocarbon systems are the cheapest, the CO2 method is the most expensive, while ethanol lies in the middle. For the record, a 25-liter CO2 machine can cost up to $400,000! A 5-liter CO2 machine costs $100,000 whereas a starter hydrocarbon system could be yours for around $20,000. A top of the line ethanol extraction system will set you back between $70,000 and $80,000, although the Ethos-6 costs approximately $90,000, and the Atles costs $400,000.
Hydrocarbon extraction is by far the most dangerous of the three. While ethanol is flammable, it carries nowhere near the same risks as butane or propane. Hydrocarbons are also an asphyxiant capable of killing a human. Let’s say there was a sudden large release of butane in a room; there is a real danger that the person doing the extraction could be suffocated.
There are industry regulations in place to make the process of hydrocarbon extraction safer. In Colorado, for instance, hydrocarbon extraction can only be performed in a well-regulated environment which must include an exhaust system to prevent explosions. CO2 is potentially dangerous because it can suffocate workers if there is a leak which replaces the oxygen in the room with carbon dioxide.
If you’re seeking a full-spectrum product with a high level of terpenes and cannabinoids, it seems as if a hydrocarbon system is the best. It extracts the best terpene profile from the starting material. However, those who use CO2 extraction claim that carbon dioxide helps extract carotenoids and flavonoids too.
Ethanol extraction comes out on top in terms of efficiently creating premium grade distillates. Ethanol is excellent for processing a huge amount of marijuana if you’re looking to extract a single cannabinoid such as CBD or THC. New technology means it is possible to extract thousands of pounds of marijuana a day using ethanol, and all you need is one high-quality machine and a few add-ons to control the conditions.
A hydrocarbon system can go through a reasonable amount of marijuana in a decent time frame, but the CO2 process is the slowest of all. Hydrocarbon extraction also uses far less energy than its CO2 counterpart. For reference, one company that uses hydrocarbon extraction can complete 18 production runs in 24 hours while another firm that uses CO2 can do just three during the same period.
Final Thoughts on Ethanol Extraction
At present, ethanol is one of the ‘big three’ methods of extracting cannabinoids, terpenes, and flavonoids from marijuana flower. Other companies are looking beyond these ‘traditional’ methods in a bid to create a more efficient and safer way to derive weed’s beneficial chemicals. For example, one Denver company is using ethyl acetate which will allow extraction without the need for expensive equipment.
For now, though, companies choose between ethanol, CO2, and hydrocarbons. Here is a quick overview of what we discussed above:
- Cost: Hydrocarbon machines are the cheapest, ethanol extraction is in the middle while the CO2 method is by far the most expensive.
- Safety: Hydrocarbon extraction causes safety concerns as the solvents are flammable and could suffocate extraction staff. CO2 uses high pressure and could suffocate workers too but is not as combustible.
- Quality: Hydrocarbon extraction provides a greater cannabinoid and terpene profile while CO2 captures carotenoids and flavonoids.
- Efficiency: Ethanol extraction is by far the most efficient, ahead of hydrocarbons.
In the end, there are pros and cons associated with ethanol. As it is a solvent, it is combustible but is much safer than propane or butane. As it has nonpolar and polar parts, and high-pressure is not required, ethanol extraction is considered to be the safest and most efficient form of extracting cannabinoids and terpenes from cannabis.
Companies like Capna Labs have introduced even more efficient ethanol extraction systems which allow firms to extract enormous amounts of terpenes and cannabinoids in a short space of time. With minimal residual chemicals, perhaps machines such as the Capna Fabrication Atles model are the new gold standard of marijuana extraction?
Other organizations are looking into alternatives to the big three methods of extraction. While it remains to be seen whether ethyl acetate breaks into the market, it is inevitable that sooner rather than later, there will be a fourth method of marijuana extraction.