Cannabis Extractions: A Primer

Cannabis extractions of any kind have made an incredible boom in both the medical and recreational markets. They’re versatile, have countless uses, and have incredible medicating properties. Many...

Cannabis extractions of any kind have made an incredible boom in both the medical and recreational markets. They’re versatile, have countless uses, and have incredible medicating properties.

Many people when they first hear the word “hashish”, they immediately associate it with outdated techniques that involve collecting resin off the fingers of trimmers, or from hands that have been wiped across thriving flowers. Although these primitive techniques are considered “concentrates”, the world of science has completely reformed how cannabis gets extracted, and how those extractions get consumed.

Cannabis can be concentrated in basically any way shape or form; however, the rise of certain solvent and mechanical extractions have been taking the industry by storm. The most infamous solvents used to process cannabis are n-butane, isobutane, pentane, n-propane, CO2 (critical and supercritical), and of course ethanol.

People may argue that isopropyl is a viable means of extracting resins, but in my eyes it should be used for disinfecting, and disinfecting alone.

If you take a look at trichomes under magnification you’ll realize that they look like tiny looking mushrooms that protrude away from the plant’s tissue. These mushroom-like objects are globular oil filled sacs atop stalks. The globular sacs are wrapped in a thin membrane that is hydrophobic (meaning it repels water), and will only fully dissolve in solvents such as ethanol and butane.

Each individual solvent dictates what the end concentrate is called (different oil consistencies also bring forth their own applicable names). Resins that have been extracted using butane are known as BHO (Butane Honey Oil: the most infamous), cannabis processed with propane is known as PHO (Propane Honey Oil: growing in popularity), CO2 extractions result you simply with CO2 oil, and ethanol extractions result in tinctures (if glycerin isn’t used), or RSO (when the ethanol is evaporated). Many more solvents are used for preparing cannabis resins but for argument reasons these are the few main ones.

Mechanical extractions are just as sought after as concentrates processed using solvents. They can actually be demanded exponentially more depending on the quality of the product and the people you ask. On a personal scale I prefer mechanical extractions for recreational purposes because you’re yielded with a 100% natural product where as solvents assist in a more replicable end product, which is more suited for medical applications. In many eyes, the difference between mechanical and solvent extractions is a smoothy made with fresh fruit or a bottle of pasteurized bottle of juice. 

The most infamous mechanical extractions are bubble hash, dry sift, and an older technique that’s making new waves is rosin. The biggest problems to get over when extracting cannabis mechanically are the inconsistencies in the end product. When you agitate your cannabis in ice and water or through dry screens, it’s very difficult to manage yields and potencies. However, with better techniques come more replicable results. Nevertheless, certain solvent techniques are much better for recreating more chemically identical products for medical applications.

A little Background Behind Different Solvent Extractions

Solvent extractions have such a wide assortment of uses and can be infused into just about anything food related. When using these natural gases to extract resins from cannabis it can be done in one of two ways: open blasting, or the use of a closed loop system.

All cannabis extractions should be processed using a closed loop system (CLS), but with any rising social trend brings a “do it at home method”. By this I mean the term open blasting”. Open blasting requires pushing store bought cans of butane through glass or stainless steel tubes packed with cannabis. The butane then goes in one end of the tube then exits directly into the atmosphere once it reaches the other end of the tube. This presents dangers for the extractor because volatile butane molecules are then surrounding you as you process. A fun afternoon can turn into a fiery nightmare with the presence of a spark. Not only is open blasting not safe for yourself and others around you, but also the end extractions contain a mystery oil that lines the inside of butane cans. All butane companies are marketing masters and claim they have the “cleanest butane on the market”. But in reality all individual cans of butane contain lubricating oils socially classified as “mystery oil”.

BHO/PHO

After my little talk on open blasting, let’s from here on out just expect that professionals, in their proper environments, using nothing but the required equipment, produce all the extractions I talk about. A second point to add is that solvents such as propane and n-butane are colourless, odorless liquids at freezing temperatures. The smell most people refer to these solvents are not actually the solvents themselves, but are compounds such as hydrogen sulfide, mercaptans, and ethanethiol. When pure n-butane and propane are evaporated, among many other natural gases, they leave behind absolutely zero residues.

BHO and many other extracts  (even other than cannabis for that matter) can be extracted using a closed loop system. These machines are big, airtight and made of stainless steel. Their main purpose is to contain liquid solvents and the pressures necessary from the atmosphere around them to extract certain plant material. As we all know now, BHO and PHO are produced using two different solvents. Although the change in butane and propane lead to a slight difference in end extraction, the solvents themselves are similar in many ways. Both gases are produced from petroleum and will release water and carbon dioxide as waste products when burned. These gases are constantly being experimented with by mixing the two together to see how it affects their boiling points and extracting potential. For instance, propane has a much lower boiling point than butane, which makes it much easier to evaporate off at room temperatures than n-butane. This results in decreased purge times and minimized residual solvents in your finished extraction.

Once the cannabis resins have been extracted and the solvents have been evaporated off, you have to finish the process by removing the remaining solvent in your extraction. This is known as “purging”. Purging is the very last step in any solvent extraction. It’s performed by placing your extraction in an airtight chamber or vacuum oven, then pulling away air from these chambers with the assistance of a vacuum pump. The purpose of pulling air is to create a vacuum, which rids any left over solvents trapped within your concentrate. Pulling a vacuum of -29 inHg(inches of mercury) is a general factory standard for removing solvents from your oils effectively. The difficulty of being able to pull a full vacuum depends on the size of your pump, the size of your oven, and the high and low pressure days in our atmosphere.

Purging at higher temperatures will remove solvents faster, but at the risk of losing other valuable compounds. Purging at different temperatures will also affect the extractions molecular makeup known as its “consistency”.

Consistencies

It’s a controversial argument as to what causes cannabis resins to alter their molecular makeup. However, there are a few speculated reasons as to why it happens. These suspects are heat, agitation, moisture, and the odd time solvents. When referring to BHO and PHO, the three-renowned consistencies are shatter, wax, and honey. Purging at temperatures no higher than 115f - 120f generally results you with shatter. When you purge at temperatures between 120f - 140f you get wax; this is when your extractions will start crystallizing both primarily and secondarily until fully “waxed” over. Agitation, moisture and certain solvents have all proven to cause nucleation in extractions. Honey is the one that’s purged at the highest temperatures. Its purged between 140f – 190f and generally comes in a fully decarboxylated form. Most of the time it can be added directly to food in an effort to avoid inhalation.

Decarboxylation

Decarboxylation is the step all forms of cannabis must go through in order to activate certain compounds and for a user to experience psychoactive effects. Decarboxylation happens to cannabis over time with the presence of light, heat and air. It simply happens at a more advanced rate as more additional heat is added. The more heat you add within reason, the faster the compounds convert to their activated form. Cannabis’ bioactive ingredients in their raw form contain carboxyl groups, and when it’s ingested orally, it stop things such as THC and CBD from passing the blood brain barrier. All the medicating factors will still be present across the body except the “high”. To activate the bioactive ingredients in your cannabis, you have to remove these carboxyl groups to allow passage across the BBB. This step here is basically reversing photosynthesis, which simply enough ads CO2 to compounds while growing. 

The way to activate your inactive marijuana is by heating your plant matter or oils for a specific temperature for a prolonged appropriate time. There are arguments as to what heat is better for which time, but generally speaking use a benchmark of 270f for 20 minutes with oil and around 130f for an hour with plant material. Generally speaking you can never fully activate THC, and that’s because once THC has hit a 70% decarboxylation point the already decarboxylated THC starts degrading into CBN faster than the inactive THCA converts to THC. So when you’re material has finally hit 70% delta-9 THC you should consider cutting the heat, unless you admire the more stony compound CBN.

Overall, cannabis is an incredible plant with an endless array of uses. It’s beautiful, calming, and necessary for the lives of many individuals on a global scale. People swear upon it as their medication of choice, and as time progresses the stigma behind it only gets lifted more and more. I look forward to writing more on this controversial little plant in future articles to come. Thank you for reading, and I really hope you enjoyed!

 - Mitchell Nixon

Mitchell is a 19 year old Canadian student who studies marketing at the Lawrence Kinlin School of Business. He loves science, cannabis, reading, glass, his family, and all other people. As of this past month, he is honoured to be able to represent Tweed inc. You can connect with him on twitter at https://twitter.com/mitchellnixon42 

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4 comments

  1. Mitchell Nixon Reply

    Just reading through this I noticed I messed up slightly and stated that temperatures no hotter than 115f-120f will result in shatter. It's true however, but comes off wrong. I should have said that purging anywhere below those temperatures will result in "shatter". The more non viscous your concentrate is, the closer to ambient temperatures you can purge. It's ideal to keep the temperature around 90f because the hotter the temperatures the more desirable volatiles you loose. Hope this helps!

  2. Alex Reply

    I thought RSO was a much more specific product that involved specific strains and technique rather than just any extraction made with ethanol.

    1. Profile photo of David Brown

      David Brown Reply

      I don't believe it has anything to do with a specific strain, Alex, but rather the process. You can read more about Rick Simpson Oil here: http://blog.liftcannabis.ca/2014/11/09/understanding-honey-oil-controversial-claims/

  3. Dianna Donnelly Reply

    THC does so much more than get you high. Anyone with nerve pain will concur. So decarbing your compounds before ingestion is not only about psychoactive effects.
    Decarbing is about changing the shape of the compound so it fits in the receptors properly. Also, CBD requires decarbing to be absorbed yet offers no psychoactive effects whatsoever. Fear of the high hinders proper use and it shouldn't since the high is simply a side effect that you adjust to over time and that can easily be mitigated with the addition of CBD.

    I wholly agree with you when it comes to raving about concentrates as safe and VERY effective mode of ingestion.