Many medical and recreational cannabis consumers prefer to inhale a cool, instantly-rejuvenating, cannabinoid-infused vapor as opposed to the comparably harsh combusted cannabis smoke. However, many health-conscientious cannabis concentrate consumers—you included, perhaps—prefer to avoid all together inhaling residual petroleum particles from butane hash oil into their lungs. We couldn’t agree more.
So are you ready for a cleaner, purer, tastier, safer and overall truly higher-quality cannabis concentrate? Well have we got a treat for you: supercritical CO2 extraction! That’s not actually the treat, though. Rather, it’s a really awesome way to remove all the stuff that makes ganja great from the plant matter on which it resides. That way, you don’t have to burn your marijuana to reap all the mind-altering and medicinal benefits. And best of all for those health-conscious cannasseurs out there, this extraction method won’t leave behind trace amounts of toxins in the finished product. Now that’s something to sit up and take notice of.
This post will break down a bit of the basics behind supercritical fluid extraction and the biochemical benefits of CO2 extracted cannabis concentrates. We’ll also leave you with some simple steps for extracting your own concentrated kief crystals at home using dry CO2 ice.
The Added Value of CO2 Extraction
Supercritical CO2 is increasingly being used as a cheap, recyclable and environmentally safe industrial solvent for creating high quality:
- Fruit and nut extracts
- Fruit and nut aromas
- Omega-3 oils
- Tobacco extractions for e-cigarettes
- Hop-oil extraction for beer
- Oil extractions from algae (as an alternative energy source)
- Cannabis oil
You may look at that list and say, “Hey, it’s cool that CO2 extraction is being used for so many different products. But why, exactly, is it so popular?” Great question! Here’s the deal.
- Our bodies naturally produce carbon dioxide (CO2) when we breathe so it’s considered a “natural” product. This is in comparison to chemicals like the chlorofluorocarbons (CFCs) found in hairspray which caused such a ruckus in the 1970s and 80s.
- The FDA considers it safe which is why CO2 is used, among other things, to keep our soda pop fresh.
- CO2 is nontoxic and CO2 extraction processes do not contribute toward carbon emission increases in our atmosphere.
- CO2 extraction doesn’t bring any flammable petroleum based solvents (like butane) into contact with your medicine. This removes the danger of explosions from the CO2 extraction process as well as potentially harmful petroleum based butane particles from the final, very fine, concentrated cannabis product!
So now that you understand why CO2 extraction is such a great process, let’s delve a bit deeper into the science behind how it works.
Supercritical CO2 Extraction 101:
Warning: The following description may seem a little complicated if you’re not an industrial chemist or if you’re not already high enough while you read this.
CO2 extraction machines essentially freeze and compress CO2 gas into a “supercritical” cold liquid state. “What does it mean to be in a supercritical state?” We’re glad you asked.
Carbon dioxide (CO2) usually behaves as a gas at standard temperature and pressure (i.e., in places where humans can survive without special equipment). That gas can be changed to a solid without much effort. This solid state is known as dry ice. These are the two most-common phases of CO2 that appear outside a lab.
With special equipment (i.e., in a lab), you can change CO2 gas into a liquid by increasing the pressure to 75 pounds per square inch and keeping the temperature below -69 ℉. Brrr! This liquid CO2 is the starting point for our CO2 extraction.
From this liquid state, we’re going to increase the temperature and pressure past a certain point. We won’t get into the numbers here because it become super complicated. Just know that when you increase the temperature and pressure of liquid CO2, the fluid becomes supercritical. This means that it can adopt properties midway between a gas and a liquid at the same time. Mind blown, right? A supercritical fluid can fill a container like a gas while still maintaining its density like a liquid.
This supercritical property of CO2 is great for chemical extraction because it is “gentler” than other compounds and won’t cause damage or denaturing (making unfit for consumption). And because the solubility in CO2 varies with pressure, supercritical CO2 can be used to extract selected compounds (rather than a combination of all compounds) with just a few small adjustments. So now that you have a passing understanding of what supercritical CO2 is, we can turn our attention to how it’s used to make cannabis extracts.
As you can see in the diagram above, you start with liquid CO2 (top left corner). You raise the pressure of the liquid CO2 via a compressor (top middle), and then raise the temperature via a heater (top right). The supercritical CO2 is then passed through some high grade pot contained in an extractor (bottom right corner). It’s at this point that the CO2 pulls all of the essential trichomes and terpene oils and/or waxes out of the plant material.
This solution (the supercritical CO2 containing all the ganja good stuff) is then passed through a separator (bottom middle) where it is broken down into its constituent parts. The trichomes, terpenes, and other goodies are sent to a collection receptacle (“Extract” on the diagram above) while the supercritical CO2 is passed through a condenser (bottom left) where it is turned back into a liquid. This liquid is then sent to the storage tank where it can be used to restart the process.
And if you’re wondering about residual CO2 left over in the extract, don’t worry. Decreasing the pressure on the CO2 after the extraction process is complete allows the liquid CO2 molecules to turn back into a gas and evaporate into the atmosphere. This is probably the simplest part of the whole procedure: just leave the extracts out at room temperature. This is the same chemical reaction that causes a soda pop to go flat after it’s opened and warms up. Some industrial supercritical machines can even simplify this process by recapturing, recycling and reusing the CO2 gases that are given off when extraction is complete.
Supercritical CO2 extraction is supercool for the future of the global ganja community because the process gives concentrate makers the ability to isolate, capture and scientifically understand, not just THC and CBD, but the more elusive cannabinoids like cannabichromene (CBC) and cannabicitran (CBT). In other words, CO2 extraction is the key to understanding the hidden medical benefits of the other, less prevalent cannabinoids and how they work together (a process known as the entourage effect) when the whole plant is used as medicine. For example, the terpene pinene helps counteract cognition malfunction and memory loss caused by THC. A combination of pinene, myrcene, and caryophyllene helps stave off anxiety. Myrcene can decrease resistance in the blood-brain barrier which can enable easier passage of beneficial chemicals. If you extract only THC or only CBD, you miss out on all the other beneficial cannabinoids that can be found in the whole plant. The absence of these substances can, at the very least, cause a bad trip and, at the very worst, cause the medicinal value of your marijuana to be zero.
The customization and flexibility of supercritical CO2 extraction means that we can delve deeper into how all these cannabinoids work together to produce the beneficial effects that we have come to know and love.
In addition, supercritical CO2 extraction will probably help growers breed wildly new strains of cannabis with undreamt of, yet-to-be discovered, miraculous medicinal health benefits. Imagine a strain of marijuana that helps reverse Alzheimer’s disease or dementia. The chemicals in the cannabis plant can have such an impact on the brain that these types of uses aren’t outside the realm of possibility.
Additional Extracted Value
As we’ve mentioned, one of the many benefits of CO2 extraction is that CO2 oils are highly customizable. Industrial concentrate makers can make pure cannabis extracts with the consistency of oil, shatter, budder or wax just as easily with the same CO2 machine simply by varying and fine tuning the temperature, pressure, solvent-to-feed ratio and the flow rate during the extraction process. The flexibility of these machines to be fine-tuned for different extracts means that products can be made cheaper than they would be if you had to have a separate machine for your oil, your shatter, your budder, and your wax. At $39,000 a pop, four machines to produce four different extracts would be quite a large chunk of change (at least $156,000 for those of you who were wondering)!
Another benefit of CO2 extraction is that running supercritical liquid CO2 through reefer kills any microbial bacteria, mold, mildew or insect mites that shouldn’t be in your weed in the first place. This guarantees that your concentrates will be cleaner and healthier for you to consume. That equals peace of mind in a world where drugs are being laced with highly-lethal products like carfentanil that result in almost immediate fatalities.
A third benefit of supercritical CO2 extraction is that there’s no need to use potentially harmful chemicals in the process. For example, in other extraction processes, ethanol alcohol is used to winterize (soaking the extract in alcohol and freezing it in order to separate the residual products) and butane is used to de-wax, or extract, the cannabis oils. The absence of these extra chemicals makes supercritical CO2 concentrates safer to consume and tastier to experience thanks to the preservation of terpene aromas. These terpenes would normally be destroyed by the alcohol or butane making your cannabis extract much less flavorful. The superior taste of CO2 extracts also makes them ideal for using in cannabis concentrates.
Dry Ice DIY CO2 Extraction
The cost of custom made CO2 weed oil can vary wildly. As we touched on above, the cost of an industrial, state-of-the-art, supercritical CO2 extraction system itself can run you about $39,000. Chance are, you don’t have that kind of coin burning a hole in your pocket. And your friendly neighborhood bank isn’t likely to loan you the money for such a contraption without a really good reason. Regardless, you can still enjoy making potent, solvent-free, environmentally safe, concentrated cannabis hash at home even if you’d rather not spend a small fortune on an industrial supercritical CO2 extraction machine. This is probably for the best as, without proper training, you risk blowing up your home by experimenting with butane hash making methods.
Thankfully, it’s very common, easy and safe to use the solid form of CO2—known as dry ice—to make your own high grade keif hash at home.
Here’s what you’ll need to get started:
- Size 73, 160 and 220 bubble hash micron mesh bags.
- A clean 5-gallon food grade plastic bucket.
- Thick, heat-resistant gloves.
- A putty knife, paint scraper or just a laminated card to collect the kief hash.
- 3 glass mason jars to store your kief hash.
- A large clean mirror or piece of plexiglass.
- Up to 6oz of cannabis bud/trim.
- Up to 3lbs of dry ice.
Make sure you follow a few simple dry ice precautions while making your cold CO2 hash.
- Don’t touch the dry ice without your gloves! Dry ice is much colder than regular ice and can burn the skin (like frostbite) almost immediately. You wouldn’t want to get any freezer burn, now would you?
- Don’t eat the dry ice. Frostbite on the fingers is bad enough, but frostbite on your esophagus is the worst.
- To be safe, consider wearing safety glasses. And if you’re going to be chipping or cutting wear a face shield.
- Don’t place dry ice in an airtight container. The CO2 given off can build up and cause the container to explode. Instead, store the dry ice in a thick styrofoam cooler to slow down the sublimation process.
- Make sure you work with dry ice in a well-ventilated area to avoid inhaling more carbon dioxide than you should.
- Safely dispose of any leftover dry ice by allowing it to warm up and transform back into harmless CO2 gas.
Simple Dry Ice Hash-Making Steps
The process of actually making your dry ice hash is fun, easy to follow and won’t take you anywhere near as long as it will take you to gather the materials you’ll need for the process.
Put on your gloves and eye protection. Safety first, boys and girls. It’s all fun and games until someone gets freezer burn!
Choose your favorite cannabis strain and chop it into small pieces with a marijuana grinder. The more surface area you can create (i.e., the smaller you grind your cannabis), the better the chances that the dry ice will get all of the mind-altering goodies from the plant material. Don’t reduce your ganja to dust, but give it a few quick turns through the grinder to make small pieces.
Place the ground cannabis in a 5-gallon, food-grade bucket. Make sure it’s a food-grade bucket or you could leach harmful plastic compounds into your final product.
Cover the cannabis in dry ice and let it sit for 3 minutes. You don’t need to fill the bucket to make this work. In fact, it’s better if you only fill the bucket about half way. The extra room in the bucket gives the dry ice room to move which makes the next step infinitely easier.
Fit your 73-sized micro mesh bag over the opening of the bucket and shake the contents around for about 4 minutes. When the cannabis comes in contact with the dry ice, the low temperatures cause the trichome resins to freeze. Then, when the bucket is shaken, the ice moves against the plant matter and knocks the frozen trichomes off.
Lift the bucket up, turn it upside down over your clean mirror or plexiglass and start shaking out as much cold powdery resin through the micro-mesh bag as you can until you can’t shake anymore out. Be sure to give the bucket a good and thorough shaking to displace as much of the resin as possible.
Next, use your scraper or card to smoothly scoop up the kief hash from your surface area into a mason jar. For 1 ounce of cannabis, expect to produce about 3.5 grams of kief. You’ll get about 0.5 grams of high-grade stuff with the smaller micron bag and about 3 grams of lesser-grade stuff with the larger micron bags.
Repeat the previous steps with the size-160 and 220 bubble hash bags in order to collect three different grades of pure, solvent-free, homemade CO2 hash. Not sure what to do with this giggle dust? Do whatever you please! Smoke it, vape it, dab it, infuse it, or bake it into edibles. The sky’s the limit with this marijuana extract.
The CO2 Cannabis Conclusion
Supercritical CO2 produces cannabis concentrates that are much safer, cleaner, less toxic and more aromatic than butane hash oil products. CO2 oil is more cost efficient to produce en masse and more customizable in terms of its cannabinoid content for the consumer. CO2 extraction is the cutting edge of the cannabis industry, however a typical supercritical CO2 machine costs way too much for most people to own and use one of their own at home. You can still make high quality, completely non-toxic, CO2-extracted cannabis concentrates at home with some simple materials, some easily obtainable dry ice and some good organic weed.