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Home > Article > Extraction & Processing

A Guide to BHO Extraction

Published: Oct 12, 2021   
A Guide to BHO Extraction

Aimee O'Driscoll
Freelance Science Writer

The vast range of products available in the cannabis industry includes a multitude of extracts. One popular type of extract is butane hash oil (BHO), also known as butane honey oil due to the raw extract's golden color and viscous texture. BHO can be processed using various techniques to create several different products, including shatter, budder, and wax.

The process used to produce BHO from the raw cannabis plant is known as BHO extraction. It uses butane as the primary extraction solvent and can yield products containing up to 90 percent THC. This extraction process has many advantages over other techniques, but it has its drawbacks too.

Here we reveal more about BHO extraction methods and how they differ from other types of extraction. We also discuss why many producers continue to favor this method and the types of products they are creating.


What is BHO extraction?

BHO extraction, often referred to as hydrocarbon extraction, is broadly used to produce high-quality and potent cannabis extracts. It is the process of using hydrocarbons as a solvent to extract the resin from the cannabis plant, Nate Fergeson, master extractor and co-founder of Jetty Extracts, told Analytical Cannabis. “The process consists of using a closed-loop hydrocarbon extractor, filling it with cannabis, then passing the solvent through the cannabis.”

The key component in BHO extraction is high-purity butane. That said, some extraction techniques will utilize a hydrocarbon blend, often with propane or isobutane added to the mix. Butane is ideal for cannabis extraction as it has a low boiling point of 30.2°F (-1°C), which makes it relatively easy to remove the solvent from the concentrated solution post extraction.

In BHO extraction, butane (usually n-butane) is used in its liquid form, which means maintaining a temperature of -40°F (-40°C). The liquid butane is washed over the raw plant dissolving desirable components including cannabinoids (THC, CBD, and others) and terpenes. As propane has an even lower boiling point than butane, it is often used to strip additional compounds (such as additional terpenes) from the plant. The solution is then deposited in the collection vessel and the solvent is removed to leave the extract, which may go through post-processing to achieve the desired final product.

Equipment typically includes closed-loop hydrocarbon extractors, de-waxers, filtration columns, vacuum ovens, and pressure vessels. BHO extraction can theoretically be carried out in an open system, but this method is notoriously unsafe and is not used by commercial extractors. Closed-loop systems are far safer, although strong precautions should be taken even when utilizing state-of-the-art equipment.

“The process is performed in a classified room, free of any potential ignition sources as hydrocarbon gases are highly flammable.” says Kim Eastman, vice president of manufacturing at Jushi.


How to make BHO:

  • The raw plant (biomass) is loaded into the extractor and solvent (butane) is applied to the material.
  • The solvent is removed from the collection vessel through active or passive recovery. Eastman explains that active recovery utilizes a gas compressor or pump to pull the solvent out of the oil and push it back into the solvent tank. Passive recovery involves the use of heating and cooling exchangers to manipulate the solvent temperature and pressure allowing transfer from the collection vessel back to the solvent tank.
  • The gas is then used for subsequent extraction runs.

Operators develop their own extraction methods to produce their proprietary products, notes Eastman. “Operators can use a mono solvent (n-butane being the most common) or a solvent blend (like butane/propane), and can adjust temperature, soak time, and recovery time and temperature,” she told Analytical Cannabis.


What makes BHO extraction different from other extraction techniques?

One of the key factors driving producers to BHO extraction is its high throughput potential. “The process is high-yielding and extremely fast with run times under 30 minutes and requires very little post-processing,” says Eastman.

“Butane has a low boiling point making solvent removal a breeze as very little heat is required. Supercritical CO2 and ethanol extraction require extensive downstream processing to remove the undesirable compounds, requiring time, labor, and added infrastructure and equipment costs.”

She goes on to explain that hydrocarbons are great for maintaining the desired plant profile in the final product.

“The chemical makeup of the solvent contains only hydrocarbon chains, no hydroxyl groups, which limits its propensity for extracting waxes and chlorophyll, the most undesirable compounds in the plant.”

In addition, the process is performed at extremely cold temperatures, which allows for selectivity when extracting desired compounds and preserves the most volatile and sensitive compounds in the plant makeup. These include terpenes and flavonoids, which represent the flavor of the plant.

While BHO extraction has its benefits, it may not be the simplest route to take. One of the key factors to bear in mind with BHO is safety. While safety is paramount in any extraction process, the behavior of butane gas makes BHO extraction particularly dangerous. If butane gas is released into the room, it accumulates close to the floor, and even a very low percentage of butane gas is considered a fire risk and could be ignited by as a spark or even static. Even where closed-loop systems are concerned, precautions must be taken to ensure that safety protocols are followed. A faulty gasket or improper check could lead to disaster.

Another drawback is that it is easy to produce hazardous products if butane extraction is not carried out correctly. Failure to purge the residual butane post-extraction could result in toxic levels of hydrocarbons in the final products. What is more, some amateur extractors use low-quality butane, which could contain unknown contaminants such as toluene and xylene. If these end up in the final product, they may pose a risk to consumers.


How do cannabis extractors utilize this technique?

Fergeson notes that some extractors and chemists would say butane is the most selective of all the solvents used to extract cannabis. He explains that BHO extractions do a great job giving the operator everything they want from the cannabis plant without picking up too many undesirable compounds during the process. This is mainly due to the polarity of the solvent and the fact BHO extractions can be done at very cold temperatures. Fergeson goes on to say that “the final result is a great cannabinoid and terpene profile that most other solvents (CO2 and ethanol) cannot compete with.”

Eastman tells us about the types of products BHO extraction is used for. “Cannabis extractors utilize hydrocarbon extraction to produce high quality extracts from either fresh frozen or cured and dried cannabis. This extraction technique allows for the largest range of products that can be produced. It is primarily used to create concentrated oil that is incorporated into vaporization cartridges or sold as dabbable concentrates sold by the gram. The oil can also be activated and incorporated into edibles, topicals, or even distilled.”

Depending on how the extract is processed, it can be converted into a range of product forms including shatter, pull and snap, crumble, budder, wax, sap, and oil.


Conclusion

BHO extraction is a versatile method for producing a range of highly potent cannabis products. There are dangers associated with the process that would deter many amateur extractors, but when carried out safely, BHO extraction offers a fast, efficient way to extract desirable compound profiles from the cannabis plant.


Aimee O'Driscoll

Freelance Science Writer

Aimee is a freelance science writer with over a decade of experience as a development chemist. She has written for Analytical Cannabis since 2020.

 

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