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Cannabis Extraction Methods Explained

By September 29, 2017 January 3rd, 2019 No Comments

Cannabis concentrates and oils are gaining popularity. There are several different extraction methods, some being safer than others that manufacturers use to make liquid for use in varying cannabis products. It is important to know the difference between extraction methods and which creates the safest end product for consumption.

This guide will discuss the different extraction methods and which are the safest to use. Always ask the dispensary or retailer what extraction method is used to ensure that you purchase a product using a method you prefer.

Dry Sieve

Dry sieve is a non-solvent hash. It’s essentially just a super-refined version of kief. Several screening processes are used so that only the heads of trichomes are left.

With this process, the goal is to remove all of the plant matter and leave just the trichomes behind. The potency will depend on the strain the trichomes are coming from. Ensure that strains have been tested for potency.

You can use the dry sieve material for making “moon rocks” (also known as dusted nugs), in topicals, in edibles and just as a booster to a week strain (sprinkled into a joint, pipe or bong).

This is a manual process that is time consuming. This allows the elements extracted to remain the most natural as they are minimally adulterated.

Butane Extraction

Butane extraction has gained a lot of attention lately. It was recently determined that butane, when heated past 750-degrees, may emit the carcinogen benzene. When inhaled, benzene may pose a health risk. When using a butane torch to heat your dab rig nail, it is important to use a temperature-controlled torch to ensure that you are not exposing yourself to benzene.

Butane is used as the solvent in this extraction process. Temperature is a main factor in the consistency of the end product. For this process, butane passes through cannabis buds and included plant materials. Once it has completed its pass, the butane is separated away from the mixture using a heating process. In some methods, vacuum ovens or pumps are used to help separate the butane out of the extracted material.

The result should be a soft, golden colored wax. The purer the extraction method, the result is shatter – or a glass-like concentrate used for dabbing.

BHO or butane hash oil is created when the shatter-like material is further broken down by heat.

Shatter is one of the most common products made using this extraction method. THC content is typically high when using butane extraction. THC content typically averages between 80 and 90-percent.

Supercritical CO2 Extraction

Supercritical CO2 extraction is one of the cleanest and safest extraction methods. It is one that many medical cannabis patients look for, simply due to the process and lack of residual chemicals in the final product. Carbon dioxide (CO2) is used to complete this process. It can convert to a liquid when pressure is applied. Using a specific temperature and pressure controlled process, the essential cannabinoids and terpenes are extracted from the cannabis plant.

The CO2 gets pushed through the cannabis plant using very high pressure. This separates the cannabinoids and terpenes away from the plant.

The oil from this process should be very clear but still have an amber hue to it.

One of the biggest benefits of supercritical CO2 extraction is that this is a solvent-free process. The leftover (or spent) plant material is also left solvent-free. CO2 is also non-explosive and non-flammable.

Using this process also reduces the degrading of the plant material and oils taken from the plant, so you are experiencing the cannabinoids and terpenes in their purest and cleanest form.

Solventless Extraction

Solventless extraction often leads back to dry sieve techniques. When you have a lot of kief, you can easily use this to make a solventless extract. To keep your kief as natural as possible, you’ll just need a pollen press. Add the kief to the pollen press and apply pressure. You’ll create a small block of kief that can be used alone or in multiple other applications.

Now, you can go a step further with your kief, and still not use a solvent. Heat the kief just slightly and apply pressure. Applying heat to create your kief block gives it a little more shelf life.

You may see instructions to use ice water, butane or ethanol. While this may make your job a little easier, it strips more plant material away. Plant material isn’t always a welcome ingredient and may reduce potency slightly, but the less you do to the kief, the purer it is.

Molecular Separation

Molecular separation is also known as high vacuum and short path distillation. A thermal degradation process allows for the separation of cannabinoids and terpenes from cannabis plants. Typically, the vacuum pressure level is 0.01 mm Hg or less. By doing so, high boiling point distillation using moderate temperatures takes place.

What’s good about this process is that the high heat isn’t applied for a long period of time. More of the compounds (cannabinoids and terpenes) are left intact and degrade less.

Ethanol Extraction

Ethanol extraction is a popular method. Plant material is soaked in ethanol. When the soaking process is complete, the plant material is put through a purging process (explained below), which removes the ethanol.

During the purging process, the solution is heated allowing the ethanol to evaporate. The ethanol can be used again later for another extraction.

Purge Extraction

Purging is typically done after the extraction process to help remove excess solvents. It is ideal to use a vacuum oven for this process. What it does is it raises the pressure inside the concentrate to flatten and stretch it. By doing so, excess solvents are stripped from the concentrate.

It isn’t easy to leave terpenes and cannabinoids intact with this process. A controlled temperature should be used. Different temperatures produce different consistencies. The length of the purge ad amount of suction applied also play a role in determining the consistency of the final product.

Closed Loop Extraction

You may not hear of this process often, but closed loop extraction requires washing cannabis with liquid butane or propane solvents. A column (made of stainless steel material) is filled with cannabis that’s been broken down. They hydrocarbons in the butane or propane then wash the cannabis.

After all of the necessary components are extracted, the extracted material goes into a vacuum oven to remove excess solvents. Lower temperatures are used to ensure that as much of the solvent is removed as possible, when successful, all solvent material should be gone.

Boiling Points

While it isn’t a good idea to perform cannabis extractions yourself, it is important to know what the boiling points of different cannabinoids and terpenes are. When making infusions, the last thing you want to do is lose the potential benefit of the cannabinoid or terpene.

Below is a simple guide of common cannabinoid and terpene boiling points:

  • THC – 315 degrees
  • CBD – 356 degrees
  • CBN – 365 degrees
  • THC-A – 220 degrees
  • CBC – 428 degrees
  • Myrcene – 334 degrees
  • Caryophyllene – 246 degrees
  • Linalool – 288 degrees
  • Limonene – 349 degrees
  • Cineole – 349 degrees
  • Pinene – 311 degrees

As you can see from the numbers above, some terpenes and cannabinoids are more sensitive to heat than others.

Closing Thoughts

These are just a few of the most common cannabis extraction methods. Some of these processes are tricky, which is why it should be left up to the professionals. The safest thing you can do at home is an infusion using olive, coconut, avocado or walnut oils. Infusions take time and require that you pay attention to the temperature of the oil. We’ll get into that in our next article, ‘Cannabis Infusions and Adding Them to Your Favorite Dishes’. We hope this helps you understand the different extraction methods and which to look for, as well as which to avoid.

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