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CO2 vs Butane

With the addition of cannabis concentrate producers into the recreational markets, new regulations will be issued to govern the safe production of cannabis concentrates.

Currently, there are two prevailing technologies that are being used at scale to produce oils, budder products and shatter; BPO (using Butane gas) and CO2 extraction technologies. But which is the superior methodology.

Which produces more?

The Colorado state government, one of my favorite sources of studies and statistics of production estimates- shows that for butane extractions, every pound of trim going in you get about 78 grams coming out.

For CO2 extraction, you can expect a little less. For every pound going in you get about 69 grams of extracts.

Winner: Butane. It’s less than a 2 percent difference in output but over time and scale, that’ll make a difference, especially since your end product will be competing on shelf price.


When it comes the THC levels, CO2 has a slight advantage over BHO. CO2 is a little bit more tune-able when it comes to the cannabinoids, oils and waxes that it pulls out or leaves behind. BHO Shatter you typically see (advertised) as 78% to 84%. Good CO2 Shatter will test at 90+ percent THC.

Winner: CO2 clearly has an advantage. Using a combination of super and sub-critical processes, you have a little bit finer of a palette to pull from in terms of what you want to leave behind.

Cost of systems

There is no comparison in terms of the costs for a production sized system. You can buy a production based Butane system for about $25,000 dollars. With Butane requiring much less pressure than an equivalent CO2 system – you can buy systems that have hoses connecting each part. CO2 systems require pressures more than 10 times as high as Butane systems and so need to be made of much stronger materials. A 20L CO2 system will run about 200K. Of course on top of that $25K you have to figure in the cost of building a room that meets firecode standards and can monitor air quality to warn of Butane leaks (figure another $50K min) and don’t forget post processing testing for mandated limits of trace solvents.

Winner: Butane is the winner here. Not by as much as you would think but it still is the winner.

Health Risks

This one is easy for CO2 systems. CO2 is used in many food practices such as decaffeinating coffee or extracting saffron. It is in the carbonation we drink.

With Butane the choice is a little less clear.

Going back a few years, the Journal of Toxicological Sciences published a report completed by the University of South and a medical marijuana testing lab and looked at 47 samples from volatile solvent based extractions. At that time they found that 80% of the samples contained trace samples of the solvents of including isopentane, butane, heptane and propane.

When done correctly, Butane based systems should only contain trace amounts of any hydrocarbons (less than 1%).

Winner: CO2 , why take a chance.

Cannabis Concentrates – Budder and Shatter

On the shelf of all dispensaries these days are a series of products that most cannabis users have never tried.  They go by weird names like budder or wax.

Just what are cannabis concentrates and how does it differ from regular marijuana? Is it stronger and how is it made.

First a bit of bio-chem background. Marijuana is a collection of 3 major chemical types

  1.  Tetrahydrocannabinol (Δ9-THC) – This is the main psychoactive ingredient in cannabis.
    It has two major related substances including THCA which converts to THC when heated. This is what bonds to the cannabinoid receptors in the brain and is what gets users “high” (and paranoid…but more of that later)
  2. Cannabidiol. The two other major compounds found in cannabinoids are cannabidiol (CBD) and, once a sample has been aged, cannabinol (CBN). These are compounds that have been studied medicinally and have been shown to have medical benefits as far reaching as reductions in symptoms related to anxiety and nausea to seizure disorders. There are about 60 other compounds in the cannabinoid family that will reveal medical properties for years.
  3. Terpines – this is the mixture of about 60 or so different compounds that produce that unique smell of cannabis that can range wildly from strain to strain. They are only present in small amounts. One strain can smell of blueberry while another smells like lemon while yet another smells like pines. Alpha-Pinene and Beta-Pinene are what gives some strains that pine smell. Those terpines have properties as an antiseptic and memory retention but the neat thing about them is that they bind to the same receptors as THC does in the brain and are thought to partially counteract the effects of THC

Okay, chemistry lesson over. Now on to concentrates

Since the 70’s, cannabis growers have been breading plants to have more of the characteristics that users want to see – namely THC. It is common to see strains with THC upwards of 23%. What concentrates do it take it to the next level and after processing the cannabis can see THC levels as high as 80-90%.

How to they do that?

There are a couple of different methodologies for creating concentrates but I’m going to focus on producing concentrates with a solvent – Butane and CO2.

By Indirectantagonist - Own work, CC BY-SA 3.0,
By Indirectantagonist

In the most simplistic terms – a solvent is used to dissolve the desired molecules (namely THC and Cannabinoids) and then a process is used to get rid of the solvent  – leaving behind as much of the desired THC and Cannabinoids in a concentrated form.

A common method to do this is by using butane. Butane as a liquid is soluble for the THC and Cannabinoids to grab onto and ride away from the rest of the plant material. After the liquid leaves the butane chamber it is left so that the butane will evaporate. There is some risk as many brands of butane contain impurities that will remain in the end product and can leave a distinct taste but it is inexpensive and how the majority of grey or blackmarket solvent based concentrates are made.

Another method (and my preferred) is by using CO2 as the solvent. CO2 under pressure and at certain temperatures can be tuned to remove different profiles including THC and Cannabinoids and is a liquid. CO2 is food safe and is a process used widely in the food industry for  decaffeinating coffee for instance.

Both of those methods produce a result that is similar –  An extract from the marijuana plant that is almost entirely made up of THC with a few fats, terpenes and waxes that remain. Here is where the post processing takes place and differentiates Shatter from Budder.


Budder takes this concentrated material that you’ve extracted from the plant and lets it dry. As the gas escapes it creates honeycomb like features in the concentrate when the THC molecules start to crystallize. Some producers will even stir the mixture to add in additional air bubbles.

The consistency of the budder will depend on a few things including the texture of the incoming oil and if the process to remove contaminants (in the case of Butane you are removing Butane molecules and in the case of CO2, you are removing water).  The end product can resemble a crumbly material (often called crumble or honeycomb) or a gooey wax called budder. Budder can contain up to 80% of the material being THC and Cannabinoids (the amount of each is dependent on the strain but most budder around 70%-80% THC and less than 1% CBD.


Shatter takes this product that remains at the end of the extraction process and uses a couple of different methodologies to remove the waxes and lipids that remain. This process is called winterization. It involves dissolving the extract in ethanol. Once the liquid is cooled, it will precipitate out the unwanted waxes and lipids leaving you with a pure cannabinoid (THC and CBD)/terpenoid mixture . The end product is placed in a vacuum oven to remove the remaining moisture and what is left is a clear sheet of amber that will shatter at room temperature. THC levels in Shatter can reach in the mid to high 80s.

Those are two of the major cannabis concentrates that are seen in the market today. Next time I will write about the different types of oils that can be formulated from cannabis extracts.