Hash oil or cannabis oil is an oleoresin obtained by the extraction of cannabis or hashish. It is a cannabis concentrate containing many of its Resin and terpenes – in particular, tetrahydrocannabinol (THC), cannabidiol (CBD), and other . Hash oil is usually consumed by Cannabis smoking, vaporizing or Cannabis edible. Preparations of hash oil may be solid or semi-liquid depending on both production method and temperature and are usually identified by their appearance or characteristics. Color most commonly ranges from transparent golden or light brown, to tan or black. There are various extraction methods, most involving a solvent, such as butane or ethanol.
Hash oil is an extracted cannabis product that may use any part of the plant, with minimal or no residual solvent. It is generally thought to be indistinct from traditional hashish, at-least according to the 1961 UN Single Convention on Narcotic Drugs that defines these products as "the separated resin, whether crude or purified, obtained from the cannabis plant".
Hash oil may be sold in cartridges used with pen vaporizers. Cannabis retailers in California have reported about 40% of their sales are from smokeable cannabis oils.
Hash oil seized in the 1970s had a THC content ranging from 10% to 30%. The oil available on the U.S. West Coast in 1974 averaged about 15% THC. Samples seized across the United States by the Drug Enforcement Administration over an 18-year period (1980–1997) showed that THC content in hashish and hashish oil averaging 12.9% and 17.4%, respectively, did not show an increase over time. The highest THC concentrations measured were 52.9% in hashish and 47.0% in hash oil. Hash oils in use in the 2010s had THC concentrations as high as 90% and other products achieving higher concentrations.
Following an outbreak of vaping-related pulmonary illnesses and deaths in 2019, NBC News conducted tests on different black market THC vape cartridges and found cartridges containing up to 30% Vitamin E acetate, and trace amounts of Fungicide and Pesticide that may be harmful.Conor Ferguson, Cynthia McFadden, Shanshan Dong and Rich Schapiro
"Tests show bootleg marijuana vapes tainted with hydrogen cyanide", 27 Sept. 2019
The following compounds were found in naphtha extracts of Bedrocan Dutch medical cannabis:
Traditional ice water-separated hashish production utilizes water and filter bags to separate plant material from resin, though this method still leaves much residual plant matter and is therefore poorly suited for full vaporization. Gold described the use of ethanol and activated charcoal in honey oil production by 1989, and Michael Starks further detailed procedures and various solvents by 1990.
Large cannabis vaporizers gained popularity in the twentieth century for their ability to vaporize the cannabinoids in cannabis and extracts without burning plant material, using temperature controlled vaporization. Colorado and Washington began licensing hash oil extraction operations in 2014. Small portable vape pens saw a dramatic increase in popularity in 2017.
The oil can also be sold in prefilled atomizer cartridges. The cartridge is used by connecting it to a battery and inhaling the vaporized oil from the cartridge's mouthpiece.
Fresh, undried plant material is less suited for hash oil production, because much THC and Cannabidiol will be present in their carboxylic acid forms (THCA and CBDA), which may not be highly soluble in some solvents. The acids are decarboxylation during drying and heating (smoking).
A wide variety of solvents can be used for extraction, such as chloroform, dichloromethane, petroleum ether, naphtha, benzene, butane, methanol, ethanol, isopropanol, and olive oil. Currently, resinoids are often obtained by extraction with supercritical carbon dioxide. The alcohols extract undesirable water-soluble substances such as chlorophylls and sugars (which can be removed later by washing with water). Non-polar solvents such as benzene, chloroform and petroleum ether will not extract the water-soluble constituents of marijuana or hashish while still producing hash oil. In general, non-polar cannabis extracts taste much better than polar extracts. Alkali washing further improves the odor and taste.
The oil may be further refined by 1) alkali washing, or removing the heavy aromatic carboxylic acids with antibiotic properties, which may cause heartburn, gallbladder and pancreas irritation, and resistance to hemp antibiotics; 2) conversion of Cannabidiol to THC. Process 1) consists of dissolving the oil in a non-polar solvent such as petroleum ether, repeatedly washing (saponification) with a base such as sodium carbonate solution until the yellow residue disappears from the watery phase, decanting, and washing with water to remove the base and the saponified components (and evaporating the solvents). This process reduces the oil yield, but the resulting oil is less acidic, more easily digestible and much more potent (almost pure THC). Process 2) consists of dissolving the oil in a suitable solvent such as absolute ethanol containing 0.05% hydrochloric acid, and boiling the mixture for 2 hours.
The majority of ready to consume extract products are produced via "Closed Loop Systems". These systems typically entail: a vessel that holds the solvent, material columns to hold the plant material, a flow meter to measure the volume of solvent entering the plant material, a recovery vessel(where heat is applied via an external jacket) to convert the liquid solvent into a vapor and separate it from the THC, CBD, or other cannabinoids/byproducts, and some form of a heat exchanger to then convert the hydrocarbon vapors back into a liquid form prior to returning to the original vessel. Such a process can be carried out using a Soxhlet extractor.
Ten grams of marijuana yields one to two grams of hash oil. The oil may retain considerable residual solvent: oil extracted with longer-chain volatile hydrocarbons (such as naphtha) is less viscous (thinner) than oil extracted with short-chain hydrocarbons (such as butane).
Colored impurities from the oil can be removed by adding activated charcoal to about one third to one half the weight or volume of the solvent containing the dissolved oil, mixing well, filtering, and evaporating the solvent. When decolorizing , oil retention can be up to 50 wt % on bleaching earths and nearly 100 wt % on activated charcoal. The many different textures/types of hydrocarbon extracts include:
This hash is then pressed at the appropriate temperature and pressure to squeeze the oils out of the hash, and is collected with metal tools and parchment paper. Just like hydrocarbon extraction, the quality of the final product depends greatly on the quality of the starting material. This is emphasized even more so with hash rosin due to its lower yield percentages compared to solvent-derived concentrates (.3-8% rosin vs 10-20% hydrocarbon). Hash rosin producers often touch on how growing cannabis for hash production is different than growing for flower production, as some strains will be deceptive with their looks regarding yields.
In the United States, regulations specifically for hash oil have not been issued as of 2019, but hemp oil – along with hulled hemp seeds and hemp seed protein – were approved as generally recognized as safe (GRAS) in December 2018, indicating that "these products can be legally marketed in human foods for these uses without food additive approval, provided they comply with all other requirements and do not make disease treatment health claim".
In Germany, the KCanG (Cannabis law) from April 1st, 2024 allows the possession of a certain amount of Cannabis products for adults. However, extraction of cannabinoids from the plants, and thus hash oil, is still illegal in general. The term extraction is not defined in the law but refers in most definitions to the use of an extractive such as butane or ethanol. As this is not used in the production of rosin it is uncertain whether rosin is a legal cannabis resin according to KCanG due to the mechanical process of production or an illegal one, since of the extractive purpose.
Solvents used to extract THC are flammable or combustible and have resulted in explosions, fires, severe injuries, and deaths.
History
Discovery and development
Modern usage
Use
Dabbing
Production
Solvent-derived/hydrocarbon extracts
Solventless extracts: Hash rosin
Legality
Ingredient in vape liquids
Adulterated products
Vitamin E acetate
Synthetic cannabinoids
Safety
Use
the health effects of using hash oil were poorly documented. Cannabis extracts have less plant matter and create less harmful smoke. However, trace amounts of impurities are not generally regarded as safe (GRAS). In 2019 following an outbreak of illnesses additives added to vape pen mixtures were found to be causing breathing problems, lung damage, and deaths.
Production
Handling
Storage
See also
Further reading
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