Hydrocarbon Extracts

2022 marks nearly half a century of solvent extractions of cannabis, and places us more than a decade away from the original explosive homebrew extractions from pioneers like Diamond Alchemy that yielded burnt-out houses and the classic “poop soup.” This means there’s a whole new generation of cannabis smokers experiencing dabbable extracts who don't know how much extraction techniques have improved since states like Colorado, Oregon and California legalized recreational cannabis and brought their extraction capabilities “online.” 

We reported on how to dab in our Intro to Dabbing round-up. Now we're going to dive deeper into the most popular extraction technique among solvent extractors: hydrocarbon extraction, or HCE. We'll also look at a technique used at the end of the process called Color Remediation Column, or CRC.

What is Hydrocarbon Extraction?

This incredibly detailed Lab Society Article will tell you everything you need to know about all the permutations of hydrocarbon extraction. In short, it’s a process of using volatile (in the sense that they vaporize easily) compounds to create a solution that isolates and extracts targeted compounds from solids or mixtures. While you can “open blast” by extracting without an expensive pressurized loop system, professional extraction facilities typically have a closed-loop system that can process anywhere from 10-100 pounds of raw flower material per day. 

I spoke with an extraction artist from Maine Craft Extractions who walked me through the technology and technique for their n-butane closed-loop extraction. “I started about six years ago on a 100g inline extractor,” says the artist, “but now we use a system with two vessels and two CRCs that can handle 10-15 pounds.” They prefer using n-butane, which creates tasty, potent extracts by binding to the active compounds in cannabis.

To extract cannabinoids, terpenes and flavonoids from the plant, non-polar hydrocarbon solvents such as butane, hexane, pentane, and propane are cooled to their condensation point. They are then pressurized with nitrogen, and blasted onto the flower in the starting material chamber. This process turns the solution to a waxy consistency. Through refinement processes (evaporation, temperature change and physical agitation) the waxes are stripped away, and solvents are purged. This leaves you with a cannabis extract containing key active compounds such as THC, CBD, terpenes and flavonoids without any contaminating plant matter. The resulting resin usually contains between 60-90 percent active compounds by volume, and can be consumed by vaping or dabbing. 

Closed-loop systems are also used for supercritical CO2 extraction and ethanol extraction, but most resins are extracted with n-butane for two reasons. First, it’s because hydrocarbon extraction processes like dewaxing and winterization require extra attachments on a closed loop system for CO2 extraction. This is an important distinction because of the second reason, which is that CO2 systems don’t scale as small as HCE systems, and the cost of those extra attachments is substantial. 

What Is CRC?

A Color Remediation Column, or CRC, is an added chamber in a closed-loop system where the extract can be filtered through media on a ferrule sintered disk. According to Precision Extraction, the most common filtration media is silica gel. Activated charcoal and bentonite clay are also commonly used. Blasting extracts through a mixture of filtration media can lighten the color and remove contaminants like mold and pesticides. However, this can mean a narrower spectrum of active compounds, and can change the scent and flavor profile from something complex and natural to a more simple, muted profile. The artist I spoke with said that a common example of this phenomenon comes from leftover limonene from silica gel filtration, which is what causes the citrus, pine and hops scent.

The most common indicators of an extract that’s been through CRC are its scent, and the paleness and tackiness of the wax. Another less certain way to tell if your extract has gone through CRC is whether the melt that you wipe from your dabbing surface with a Q-tip is clear or dark. If it’s dark, you can be fairly certain that it didn’t go through color remediation. It’s likely an extract has gone through CRC if you notice more than one of these signs. We should also note that CRC is not the only method for mechanically filtering extracts.

Should I Be Concerned About CRC?

A recent update to Oregon’s OLCC rules banned CRC with “reactive” filtration media like bleaching clay, which they allege “generates artificially derived cannabinoids” such as Delta-8 THC (an isomer of THC with a bond on the 8th carbon on the chain rather than the 9th like Delta-9 THC)  and CBN. However, most filtration media isn’t considered bleaching clay (even bentonite clay, which is a naturally occurring component of bleaching clay) and not every filtration medium is reactive. 

The bigger concern as a consumer is false advertising. Black-market extracts that have been through color remediation can be passed off as being higher quality. A cured resin that’s been through CRC might be listed as a live resin because of the paleness and the size of the THCa diamonds. Particularly saucy resins that have been through CRC might even be listed as rosin by unscrupulous gray and black market vendors who capitalize on the fact that consumers can’t smell the extract until they get home to their rigs. 

A Breakdown of Hydrocarbon Extracts

Hydrocarbon resin extracts are typically categorized by the starting material, solvent used and consistency.

  • Live resin is extracted from frozen, fresh-from-harvest flower.
  • Cured resin is extracted from flower that has been dried and cured, and would normally be ready to smoke.
  • Nug run is when the extract is made with full nugs, and should all be the same strain unless otherwise specified.
  • Trim run is extracted from a mixture of plant trim, smalls, larf and sugar leaves from one or several strains. Trim run can produce perfectly acceptable extract if you have enough starting material.
  • BHO is any hydrocarbon extract that uses butane as the solvent. It stands for Butane Hash Oil, but it’s highly debated whether the solvent extraction is considered hash.
  • PHO is the same idea as BHO but with propane
  • Shatter is called so because it’s brittle at room temperature and prone to shattering. You can sometimes find stable slabs of shatter, but the waxy, pull-n-snap consistency shatter is more readily available.
  • Batter/badder/budder is the softest consistency of resins that looks and spreads sort of like butter. 
  • Sauces are usually higher in terpene content. Microdiamonds mixtures usually have the consistency of applesauce. Sauce mixtures have varying names depending on how big the diamonds are.
  • Diamonds are any extract where the THCa has “crashed” together forming larger crystals that take mechanical force to break. Larger diamonds are called boulders.
  • Sugar wax is usually a shatter or a crumble that has nucleated from oxidation, and looks partly like wax and partly like table sugar.
  • Crumble is any crumbly extract regardless of its moisture level, which usually has the luster of a hardboiled egg yolk. 

The Takeaway

There are a lot of brands and influencers in the regional and national cannabis communities who have decried hydrocarbon and other closed-loop extractions in favor of solventless extracts, which they say is a purer experience that is closer to smoking flower. The reality is that vaporizing dabbable extracts and smoking flower are just different experiences. Hydrocarbon extractions with CRC are scientifically pure on a sub-micron level, whereas physically extracted hash can contain contaminants as large as 70 microns thick.

Just like solventless extracts, the “fire in, fire out” rule applies. While physical extraction depends on a specific size and shape of resin globules for efficient extraction, closed-loop extraction doesn’t have that limitation, which means a much greater variety of flower genetics is suitable for extraction. If done by professionals with proper equipment and precautions taken, hydrocarbon extraction efficiently produces dabbable extracts that are potent, flavorful and safe medicine.