Here’s a short guide to the different forms of hemp extract commonly available today.
Smokeable flower is a form of hemp that most closely compares to classic marijuana “buds”.
In order to produce smokable hemp flowers, the hemp plant must be grown and harvested much like marijuana. It starts with all female plants, usually either by clones or by feminized seeds, and the plants are carefully nurtured through a growth period and into a flowering period. The treatment of the plant during flowering is extremely important, as this is the time that the plant produces the vast majority of cannabinoids and terpenes. It is also a vulnerable time for the plant, where malnourishment, pests, or infections can easily destroy the flowers. However, since the flowers are being grown for direct consumption through inhalation, any residual pesticide, mold, or fertilizer can end up in the final product, so extreme care must be taken.
The unfertilized flowers are allowed to grow until they are covered in small sticky trichomes, which contain the majority of the cannabinoids in the plant. Then the plants are harvested and hung to dry and cure in an environment carefully controlled for temperature and humidity. If the plants get too hot or dry, they’ll lose the delicate terpenes that give them aroma, flavor, and the medicinal effects of those compounds. If the plants get too wet or cool, mold or bud rot can set in and destroy the flowers. Once they are dried and cured, the flowers are then trimmed from the stems and leaves. The overall CBD content of these manicured flowers can be over 15%, compared to an overall average in the whole plant of 7% or less.
Flowers prepared in this way can be smoked or vaporized in a dry herb vaporizer, or they can be further extracted into concentrates. These flowers contain everything in the hemp plant, from terpenes and cannabinoids to fibers and waxes. Smoking hemp flowers has become very popular, as it is the most direct way to consume the plant in its entirety, but currently most CBD users prefer routes of administration other than combustion.
While still rare in the CBD world, solventless extracts have become very popular in the marijuana market. The most classic form of solventless extract is hash, which is made by using cold temperatures and/or water to separate the trichomes from the cannabis flowers. This yields a sticky powder that can be rolled or pressed into lumps, which can then be vaporized or smoked. More recently, there have been methods and tools developed for using heat and pressure to squeeze out the oils from cannabis flowers to produce “rosin”.
Hash and rosin can be very enjoyable concentrates that contain the majority of the distinctive characteristics of the plant they came from. However, these are very labor intensive processes with low yields, and are thus best suited for artisanal concentrates. If you enjoy exploring the growing diversity of hemp flower strains, but prefer to avoid smoking plant material, well made rosin or hash is a great way to go.
Many people seeking a cannabis extract for severe conditions, such as cancer treatment, end up hearing about “Rick Simpson Oil” or RSO as the most concentrated cannabis extract available. This concentrate is made by using warm alcohol (originally isopropyl, now commonly ethanol) to extract all the water or oil soluble components from cannabis flowers. The alcohol is then evaporated off, leaving behind the cannabinoids, flavonoids, chlorophyll, and any terpenes that didn’t evaporate away with the alcohol.
The result is a thick, sticky tar-like material that is very dark green, nearly black. It is commonly used by taking it orally like a pill, or sometimes as a suppository. The CBD concentration can be over 50% in hemp RSO, and most of the other active components of the plant are also contained in the concentrate. The taste, however, is pungent, and there are generally more pleasant ways of enjoying hemp concentrates. When medicinal benefit is the primary consideration, however, RSO is a great option.
By and large, the primary form of hemp concentrate used in tinctures, topicals, and other hemp oil products is called “Full Spectrum Extract”. There are a few ways of producing this form of extract, which we will explore in a separate blog, but all methods produce a similar FSE.
FSE is made using a solvent to extract the cannabinoid and terpene rich oils from hemp biomass. The most common solvent used in hemp extraction is ethanol, whereas the THC concentrate market typically uses butane or propane. Some extractors use liquid or supercritical CO2 for their extractions, as well. Each method has benefits and drawbacks:
Ethanol is efficient and relatively safe and simple to use, but some of the beneficial terpenes end up commingled with the ethanol after it is distilled back off. Ethanol extraction is the most scalable form of solvent extraction currently available in the hemp/CBD industry, with some systems capable of extracting oil from 1000 lbs of hemp per day. At this scale, the quality of the hemp being extracted is typically called “biomass”, and it’s been grown and harvested at an industrial scale. This hemp is not smokable quality, and the “crude oil” produced from it often needs a substantial amount of post processing to remove waxes and other undesireable compounds, as well as any pesticides, molds, or other harmful contaminants that might have been in the hemp. In some cases, this crude oil must be processed all the way to CBD isolate in order to remove the harmful materials. Not all ethanol extracted hemp oil comes from industrially grown and extracted biomass, however. Many smaller processors, like Lux Botanics, utilize ethanol at a craft scale, using only organically grown hemp flower, extracting with non-denatured food grade ethanol at cryogenic temperatures. We pay a significant premium for hemp that meets our quality standards, and the resulting oil is truly medicinal grade and usable as-is.
The other approach to FSE production uses liquid butane, propane, or CO2 to extract the terpenes and oils, and then boils the liquid off at room temperature to leave behind only the oils from the hemp. Butane and propane are sometimes used for hemp extraction, but they are more commonly used to produce high quality THC concentrates. A butane extracted cannabis oil is often called BHO for “butane honey oil”, which describes the typical golden honey like consistency of a well performed butane extraction. This BHO is generally rich in aromatic terpenes, as well.
Due to the safety and environmental challenges with hydrocarbon extraction, along with the generally lower terpene content of hemp flowers, it’s more common to see CO2 used to extract hemp. Supercritical CO2 has some additional versatility over hydrocarbons due to its ability to be made selective for specific types of compound by controlling the pressure and temperature of the process. In our experience, CO2 extraction produces a very high quality FSE that preserves many of the terpenes that we are unable to separate from our ethanol extractions. This CO2 extracted oil may still be called a “crude oil”, and we further process it to capture terpenes, remove water and waxes, and decarboxylate it into an FSE. The primary issue with CO2 extraction is the high cost of equipment capable of accurately controlling a supercritical fluid at over 5000psi.
Typically, you will not find a hemp FSE for sale it’s pure form. This is due to the THC concentration in these extracts. Currently, the majority of the hemp strains available for extraction have CBD to THC ratios of around 30:1. This means that a hemp flower with 10% CBD will have a total THC content of around .3%, which is the legal limit for decarboxylated d9-THC. When this is concentrated to a 50% CBD content, the ratio remains the same, and THC content rises to 1.5%. So, processors must dilute the pure FSE down to .3% THC in some form of carrier oil suitable for the intended use of the product.
Some craft hemp oil producers take the purification of the oil further to make what’s known as distillate, or broad spectrum extract. For this type of oil, an FSE is vacuum distilled to separate the terpenes and other light volatiles, cannabinoids, and heavy gums and waxes into “fractions”. The terpene and cannabinoid fractions are kept, and the unwanted waxes and gums are discarded. The high cannabinoid fraction is called “distillate” or “broad spectrum extract”, and it usually consists of >75% CBD content on the first distillation pass. Much like distilling spirits like vodka, additional distillation passes can be performed to further enhance the cannabinoid percentage. Typically, the full spectrum of cannabinoids in the oil are collected and concentrated, hence the term “broad spectrum”, which is full spectrum minus terpenes and other compounds.
High quality distillate is virtually tasteless and odorless, and it serves as the base for CBD products where taste is paramount, such as vape products. It is also very useful for products where terpenes may not be wanted, such as pet products. Lux Botanics uses distillate for our tincture line due to the pleasant taste at high concentrations, as well as in our vape products. Like FSE, however, distillate can’t be sold legally as is due to its THC concentration. Some manufacturers are able to remove the THC fraction using flash chromatography, and others are finding ways to oxidize or isomerize the THC into other compounds like CBN, but most of the time distillate is diluted into a carrier oil to bring the THC levels back down to conforming levels.
In some cases, only CBD is desirable, and other cannabinoids and terpenes are not wanted in the final product. Often, processors need to take extracts all the way to isolation in order to remove pesticides or mycotoxins that were present in the original hemp biomass. In this case, the CBD isolated from the rest of the cannabinoids. This is typically performed by dissolving a distillate in a non-polar solvent such as pentane or heptane, and then chilling it, which causes the CBD to precipitate out as crystals while other cannabinoids remain dissolved. The CBD crystals are then filtered out and purged of any remaining solvent, yielding a sugar like CBD isolate with over 99% purity.
CBD isolate is used in many products for many reasons. For one, CBD isolate is often cheaper and more available for manufacturers than distillate or FSE, since it is imported in large scale from China, Europe, and Canada. Some hemp grown by large scale conventional growers in the US needs to be taken to isolation, as well, due to pesticide application. Powdered CBD isolate can also be easier to use for manufacturers, since it doesn’t require additional processing of any kind and can be added directly to recipes.
From a consumer’s perspective, products made from CBD isolate may be preferable since they have zero THC, so there will be no worry about false positive drug test results or unwanted cannabinoids. However, CBD isolate derived products will not provide the “entourage effect” of a full or broad spectrum extract.