Cannabis Extraction Methods: BHO Butane Extraction
Butane hash also known as “butane honey oil,” is a type of extract that is made using small scale extraction equipment and butane solvent. Large scale THC extraction differs from BHO because it is performed in a hydrocarbon extractor in a space that is ventilated according to C1D1 and C1D2 fire codes. BHO techniques involve “open blasting” that is broadly illegal in most situations and most states for a number of reasons.
Cannabis concentrates like BHO and other dabbing products like shatter, crumble, wax, and budder are typically used as recreational products while also have great medicinal value. Medical marijuana patients sometimes need very potent and fast-acting doses of THC. Concentrates are one of the few products that can deliver this. While dabs often get a menacing reputation for their recreational use, it is important to understand that they can be an important medicinal product.
What is in BHO?
BHO results from extracting cannabis flower. The process can also be applied to hemp to create CBD concentrates. The butane solvent strips the plant material of its essential oils and plant compounds and concentrates them. In either situation, the result is a concentrated oil that contains plant cannabinoids, terpenes, and other plant compounds.
BHO can be contaminated by plant material that contains heavy metals and pesticides and results in a highly toxic concentrate. It is vital that all plant material and extract be tested to make sure that the undesirable materials have not been concentrated with the desired, final product.
Another concern for BHO is residual solvent and impurities from the butane solvent. Only very high purity butane should be used when doing BHO extraction. The resulting concentrate should also be tested to make sure no residual solvents are present.
How to Make BHO
There are two main ways to perform BHO extraction. One is very dangerous and broadly illegal. The other is a very safe and efficient manufacturing process.
Large Scale THC Extraction with Butane Extractors
Closed-loop hydrocarbon extractors for BHO extraction are a very safe and efficient type of cannabis extraction equipment. These systems are for use in manufacturing environments that are C1D1 and C1D2 compliant. Butane extraction equipment is very efficient and can process material faster than CO2 extractors and at a fraction of the cost. Many people also feel that butane produces concentrates that have a better flavor than other extraction methods.
Large scale THC extraction within a closed-loop hydrocarbon extractor is very safe because the highly flammable and combustible butane gas is not released into the atmosphere. Instead, closed-loop butane extraction equipment recovers the butane after it passes through the plant material.
BHO extraction systems can run at low pressure, around 150 PSI. The areas around the extraction equipment should be properly ventilated per fire code to ensure that the gas does not accumulate should it happen to leak from the system. In addition to ventilation, special electrical wiring is required around the enclosure and special explosion-proof equipment must also be installed inside the extraction space to eliminate ignition sources.
Non-Commercial BHO Extraction
BHO extraction is safe when done properly with professional extraction equipment in a certified lab by a trained operator. However, the open blasting method used to make BHO is very dangerous. This method releases highly flammable and explosive butane gas into the air. The butane gas does not float up or fall to the floor, it hangs in the air one foot or so from the ground where many electrical components are located. These electrical components can spark can lead to a full-on explosion!
For this reason, especially, open blasting is illegal in most situations. Special permits may be granted to labs or dispensaries in some states. However, making your own BHO at home is very dangerous and illegal. Still, many people experiment with using glass or stainless steel extraction tubes and canned butane lighter fluid to produce BHO at home.
In addition, another danger exists because butane lighter fluid is not intended to be used to produce consumable products. Without lab testing, there is no way to know for sure that all of the butane solvent has been removed and that it has not introduced any other contaminants into the extract.
Regardless of the regulatory status of marijuana in a state, home “blasting” is considered in most jurisdictions to carry the legal consequences of operating a drug lab with strict penalties due to the risk of explosion.
Butane is a flammable gas that is heavier than air. It has a lower explosion limit of 1.6% and an upper explosion limit of 8.75%, meaning that the air becomes explosive when it is being mixed with only 1.6% butane. The butane that escapes from the extracted substance as a vapor eventually pools on the lowest surface available and flows until it finds an outlet that allows it to dissipate, rather than “off-gassing” as is the nature of other solvents. These vapor pools are easily ignited by a spark, flame, or static electricity and are the cause of the majority of the harms associated with butane hash oil production.
Al-Zouabi I, Stogner JM, Miller BL, Lane ES. Butane hash oil and dabbing: insights into use, amateur production techniques, and potential harm mitigation. Subst Abuse Rehabil. 2018;9:91‐101. Published 2018 Nov 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6220730/
Health Dangers of BHO
Smoking BHO dabs can be dangerous if the butane has not been fully purged during production. Inhaling butane solvent has been associated with chronic problems such as cardiomyopathy, renal damage, liver damage, and a variety of psychiatric syndromes according to Al-Zouabi, et al. 2018. These BHO dangers are typically related to illegally produced open-blast BHO. Licensed and certified labs must comply with health and safety measures and testing that prove the risks of solvent inhalation have been mitigated.
Types of BHO Extracts
Butane is an excellent solvent for cannabis extraction. There are two main types of extracts that are produced with butane. These are BHO wax and BHO shatter.
Subcategories include sugar crumbles, wax crumbles, and butter wax
Does not usually have a full crystalline structure
Sugar crumbles have a crystallized surface
Wax crumbles crumble apart easily but have a smooth, slick surface
Highly desirable butter waxes are creamy and silky
Shatter concentrates vary from a thin, oily consistency to a brittle and glass-like structure
Final consistency can vary based on temperature, humidity, and production techniques
Differentiated by how translucent it appears however that does not necessarily reflect its quality
A Scientific Look at BHO Extraction
Commercial and at-home BHO extraction processes greatly differ in method and legality. However, the fundamental mechanisms are the same.
Tetrahydrocannabinol (THC), other cannabinoids, terpenes, and plant compounds are concentrated in trichomes. Trichomes are the little crystals on dried cannabis flower that give it a frosted appearance. They are actually tiny resin glands, the same ones that collect in the bottom of weed grinders.
The plant compounds inside the trichomes are hydrophobic, meaning they do not dissolve in water. A solvent is any substance that is used to extract material from a matrix (like plant biomass). Water is a good solvent for hydrophilic compounds that it can dissolve. In the case of oily substances, you need a different type of solvent though. Alcohol and hydrocarbons (like butane) are two types of solvents that can dissolve oily compounds like those from cannabis.
The plant compounds in BHO have their own chemical structures. Depending on how the extraction is performed, they can rearrange molecules to create structures like crystals that are very pure and concentrated. Both physical and environmental factors can influence what the final extract sets up to look like and what texture it will take on.