Solvent-free Extracts and Concentrates
Solvent extracts used to be the norm, but many producers are now focusing on solvent-less. Here’s why.
Over the last 10 years or so, an expanding acceptance of medical and recreational cannabis has spurred an ever-increasing number of cannabis-based products to hit the market. The demand for high-potency marijuana extracts, in particular, has led to a wide variety of products and methods of extraction. Cannabis extracts and concentrates can be separated into two categories: solvent extracts and non-solvent extracts. Until recently, solvent-based extracts were the most prevalent. However, there is an increasing number of cannabis producers and users who are making non-solvent extracts a top priority.
As the name suggests, solvent extracts rely on a solvent to remove the psychoactive ingredients from the plant material. Isopropyl alcohol cannabis extracts have been around since the 1980s and are the type of solvent-based extracts that many cannabis users first experienced. Nowadays, most solvent-based cannabis extracts utilize butane, ether, or lab-grade naphtha. Rick Simpson Oil (RSO) is a solvent extract very popular among medical marijuana patients. Rick Simpson Oil is most effectively made with lab-grade naphtha, though it is also commonly made with ether. Other popular solvent-based extracts include butane honey oil (BHO), wax, and shatter.
Anyone can use solvent extracts, which are some of the most potent cannabis products on the market, but producing them should be left to the professionals. The solvents used for cannabis extractions are extremely volatile and potentially dangerous. Each year, many people are injured by accidental fires and explosions caused by haphazard extraction techniques.
Another potential problem with solvent-based cannabis extracts is the possibility of solvent residue left on the cannabis. Again, solvent-based extractions should be left to the professionals who have the proper equipment. When processed correctly, a solvent-based extract is safe to consume. However, solvent extractions that are not properly purged or are otherwise processed incorrectly could lead to the end-user consuming harmful residuals left by the solvent. For this reason alone, many cannabis enthusiasts are exclusively choosing solvent-free cannabis extracts.
Solvent-free extracts, or cannabis concentrates, are made without the use of a chemical solvent. Solvent-free extraction methods can produce some very potent cannabis products that are comparable to solvent-based extracts. Solvent-free extracts include kief, bubble hash, rosin, and supercritical CO2 cannabis oil.
Making kief is something that just about any cannabis consumer can do. Kief is made by a process called dry sifting, which can be done by hand or by a machine (sometimes called a pollinator). Dry sifting involves shaking or moving the dried flowers and/or leaves on a fine screen (usually made with 120-150-micron mesh) until the trichomes fall through the screen and are collected. A mechanical device can be used to “tumble” the plant material through the fine screen material. Once collected, the kief can be consumed as is or pressed into hash.
One of the most popular non-solvent extraction techniques is to use bubble bags to produce an ice water cannabis extraction. In this process, the plant material is mixed with ice water to get the trichomes cold. This is typically done in a five-gallon bucket or a plastic garbage bin. Inside the holding container are a series of bags, each with mesh of a different size. After heavily agitating the ice water (which breaks the trichomes away from the plant material), the bags can be lifted out, one at a time, each straining plant material in the process. The first bag to be removed will contain the majority of the plant material and the last bag to be removed will contain the highest concentration of THC and other cannabinoids. After the cannabis extract has dried completely, it can be enjoyed like other hashes. The hash made from the cannabis collected from the final bag will often actually bubble when smoked.
Perhaps the most exciting development in the non-solvent extract game is the introduction of rosin. Rosin is a solid form cannabis extract made by administering pressure and heat to vaporize volatile liquid terpenes. In layman’s terms, rosin is made when cannabis material is put under extreme pressure while also heated to a desirable temperature (somewhere between 250-335˚F). Rosin extraction is not only safer, but it is also significantly cheaper to produce than solvent-based methods. It is also quickly becoming the most popular cannabis extract because it is just as potent as any solvent-based extract and doesn’t have the potential dangers associated with the solvents. For these reasons, cannabis concentrate producers and health-conscious cannabis consumers are flocking to rosin. Rosin is very likely to be the fastest growing concentrate in the cannabis extract marketplace.
Supercritical CO2 Cannabis Oil
Although supercritical carbon dioxide (CO2) would technically be considered a solvent, I listed supercritical CO2 under solvent-free extracts because CO2 will not leave any chemical residuals, unlike the other solvents used for cannabis extractions.
Carbon dioxide behaves as a gas in the air at standard temperatures and pressure. When the pressure and temperature of CO2 are increased over what is known as the “critical point,” the CO2 can have properties between a gas and a liquid. This is the supercritical CO2 that is becoming a popular industrial solvent due to its ability for effective extractions and its relatively low environmental impact. After the extraction process, the CO2 pressure is released, and the remaining liquid CO2 molecules convert back into a gas, which then evaporates into the atmosphere.
To make a high quality supercritical CO2 cannabis oil, the processor needs to have the proper equipment. Supercritical CO2 devices made specifically for cannabis extraction have a liquid CO2 storage tank, a compressor, a heating element, a separator, and a condenser. Some of the most sophisticated supercritical CO2 extraction machines will even recapture and reuse the CO2 gases given off after the extraction process.
Marijuana patients and consumers are always looking for a higher quality and more potent product. Solvent-based extracts created a boom of BHO enthusiasts, who strove to find the most potent cannabis concentrate available. Unfortunately, the BHO boom also led people to experiment with extraction techniques that are better left to the professionals. Many people want to produce a high potency cannabis extract without the risk of fire or dangerous chemical residuals. With the use of non-solvent extraction methods, cannabis users can safely experiment with different extracts until they are satisfied. Most non-solvent methods require minimal equipment and can easily be done in the privacy of one’s own home. With a small investment, people can even produce their own rosin at home. After all, producing the highest potency cannabis extract possible without risking their life or health is something all cannabis enthusiasts can get excited about.