Solvent based extractions typically produce concentrates that are known as oil. If made properly, this means the concentrate will be free of plant matter (also known as contaminate). These oils will melt and vaporize to nothing – meaning very minimal residue will remain on the nail if dabbed, for instance. The consistency of solvent-based cannabis concentrates varies greatly based on a few factors: strain of cannabis, grow conditions, curing environment, extraction technique, solvent used, purging process and equipment used all play a role in the final product.
Butane Hash Oil (BHO)
Cannabis concentrate derived from a butane-based extraction is referred to as Butane Hash Oil or BHO for short. BHO is by far the most popular concentrate of late as a result of its potency and varying consistencies; shatter, budder, sap, snap n' pull, and sugar can all be derived from butane extraction. Although dangerous to make at home, sophisticated machinery has made commercial production safe and effective. BHO should be produced by a reputable extractor who understands how to properly purge each run to avoid unpleasant aftertaste or harsh residual butane.Perhaps the best analogy for how it works is an espresso machine: as the water passes through the puck of ground coffee beans it strips them of their oils (which contain the caffeine, flavor, and aroma) into a filtered, highly concentrated solution. For cannabis, the extractor places plant material in a column with a filtration screen at the end, and as the butane passes through the column it strips the plant material of its cannabinoids and terpenes.The solution containing both butane and beneficial cannabis compounds is then placed in a vacuum oven in order to evaporate, or purge, the BHO of its butane and any other foreign contaminants. There is almost always trace amounts of butane in the oil produced by these extractions, so try to minimize your risk by purchasing lab-tested BHO. Some legal states have begun to place maximums on the amount (PPM) of residual solvent allowed in BHO sold in dispensaries. Make sure your oil is properly purged!
Propane Hash Oil (PHO)
Concentrate derived from a propane-based extraction is referred to as Propane Hash Oil, or PHO for short. Although others are possible, the consistency of PHO is typically budder. The process of propane extraction is very similar to butane extraction, the primary difference is simply swapping butane for propane. Propane extractions run at higher pressures, stripping different ratios of plant waxes and oils than butane which, depending on the strain, can deliver less residuals and higher levels of terpene preservation. Propane has a lower boiling point than butane, which allows for a lower purging temperature for PHO and results in the buddery consistency as opposed to shatter. Note that some extraction companies utilize a blend of propane and butane.
CO2 oil is the golden liquid used in almost every pre-filled vaporizer pen cartridge. CO2 oil is substantially safer than propane and butane-derived extracts. CO2 oil is a clean, dab-able product once removed from the extraction machine with no harmful residuals or risk of toxicity. Another upside to CO2 extractions is that it kills any mold or bacteria present in the plant material. Although safer to consume, in my experience, CO2 oil lacks the flavor profile (terpene content) present in BHO and PHO. CO2 oil is commonly used in edibles and can be purchased in its activated form.CO2 extractions almost always produce a viscous oil (color can range from amber to dark) that is typically delivered in an oral syringe. However, secondary refining processes can bring CO2 extractions to a stable, shatter-like state.Supercritical or subcritical carbon dioxide extractions involve holding the CO2 at high or low pressures, respectively; the process involves extremely expensive extraction machines. The CO2 passes through the cannabis material and strips the plant of its oils, waxes and other matter. By adjusting certain parameters, the extractor can save more cannabinoids and terpenes in order to preserve purity or strip more unessential material like chlorophylls to increase yield.
Concentrates can also be created by soaking ground cannabis in alcohol (either isopropyl or Everclear). A short soak is all that is needed to isolate the cannabinoids and terpenes from the starting material. A longer soak will also dissolve undesired plant materials like chlorophylls and waxes. Alcohol based concentrates are safe to make at home and are safe to consume, assuming the solution has been filtered and purged. Purging, or evaporating, the alcohol requires precise temperature control and patience. This type of concentrate, also known as Rick Simpson Oil, is typically consumed orally or via tincture. This type of concentrate is generally purchased for medical application due to its potent cancer fighting properties as opposed to recreational use.
Distillation, also known as isolation, is a form of extraction and refinement that separates full spectrum plant oil into its individual constituents – meaning you can isolate the THC, CBD, and terpenes individually from a batch of full spectrum oil. This allows the extractor to achieve extremely potent concentrates that only contain one of the many compounds found in the cannabis plant. Although it is generally accepted that full spectrum extracts provide higher medical efficacy, isolate is useful because it gives people access to specific cannabinoids (like CBD) in higher quantities than can be found in flower. For instance, CBD isolate typically contains 99% CBD, indicating a very pure product. Another benefit to CBD isolate is that it can be shipped all over the U.S. because it doesn’t contain any THC.
Solventless extractions are considered to be the most enjoyable, highest quality, and most unadulterated form of cannabis extracts. Even better, all the solventless extraction techniques can be performed at home with relative ease. With the exception of rosin tech, the goal of solventless extracts is pure glandular trichome head isolation, as the heads contain the coveted cannabinoids and terpenes. For all those reasons, solventless extracts are my recommended and preferred concentrate despite the extra steps needed to press it into dabs. Pure isolated trichome heads in either the dry sift or ice water hash form is known as full melt. The term full melt is used to describe the highest grade of solventless extractions that melt fully, leaving behind little to no residual residue, indicating very little plant matter in the product.
Dry sift involves using a series of taut silk screens with varying microns to separate the trichome heads from the stalk and plant matter. A micron is a microscopic unit of measurement used to identify the size of the holes in a sifting screen. It is the most natural and unobtrusive way of producing concentrates; it also happens to be a meticulous process that results in low yields. For this reason, quality dry sift is difficult to find and extremely expensive, even in legal states, as commercial growers see significantly higher returns on solvent based extractions. Nonetheless, it's arguably the most flavorful concentrate because it retains the most volatile terpenes and preserves the richest aromas.There are different grades of dry sift ranging from kief, which contains a mixture of trichome heads, stalks, and plant material to full melt, which contains just the glandular trichome heads. Expert hash makers can 'clean' lower grades of dry sift, refining the material further to improve quality. As the name indicates, full melt dry sift leaves little to no residue when dabbed, and is considered to be ultimate connoisseur grade hash. It's starting material is typically of the highest quality, which results in an incredibly pure concentrate that does not introduce any foreign substances during the extraction process. This type of concentrate typically looks like beach sand and can be pressed into a dab-able sheet with light heat and pressure.
Ice Water Hash
Ice water extraction is very similar to dry sift; however the process incorporates ice and water to break the brittle trichome heads off of the plant material. The agitation can be performed by hand or with the help of a washing machine. The solution containing the water and trichomes is then filtered through what is known as a sieve stack, or a series of filtration screens of varying microns. The purpose of the screens is to remove any contaminate (plant material) and to isolate the glandular trichome heads.The final step in the ice water extraction process is to break down the hash into smaller pieces using a microplane or metal strainer so it can properly dry. Some commercial hash makers skip this step and opt to utilize a freeze dryer instead. Once the ice water hash is free of moisture, it is typically placed in an air-tight glass jar to cure; the longer the better. Like dry sift, there are varying grades of ice water hash. Quality ice water extractions also take on the consistency of beach sand and can be pressed into dab-able sheets. Cannabis extracts produced using this technique have a variety of names; bubble hash, ice-o-lator hash, full melt, solventless wax, ice wax, etc.
The newest trend in cannabis concentrate production is referred to as the ‘rosin tech’ or ‘solventless hash oil’ (SHO). Rosin is great as it provides consumers a safe alternative for making oils within the comfort of home with easy-to-access starting material; all you need is a cannabis bud. This process utilizes heat and pressure to extract the essential oils from the flower or hash.The consistency, yield, and flavor profile of rosin will vary based on strain and the specific amount of heat and pressure utilized; but as a general rule of thumb, lower temperatures and higher pressures result in the least adulterated, most terpene-rich extracts. This can be performed using a simple hair straightener or an industrial press. The rosin tech typically produces a glassy, stable oil that takes on a shattery consistency; but like most concentrates, you can find it in a variety of consistencies.The rosin tech can also be used to extract the essential oils from lower grades of ice water hash or dry sift; effectively turning your trash into treasure! Depending on the starting material used, the product will be labeled as either ‘flower rosin’ or ‘hash rosin’. Want to learn more? We have put together detailed instructions on how to make rosin as well as the best ways to consume it.https://keytocannabis.com/blogs/cannabis/what-are-cannabis-concentrates-a-guide-to-extraction-techniques