Hash oil

Closeup image of a drop of hash oil on the end of a needle

Hash oil is an oleoresin obtained by the extraction of marijuana and/or hashish.


The tetrahydrocannabinol (THC) content of hash oil varies tremendously, since the manufacturers use a varying assortment of marijuana plants and preparation techniques. Dealers sometimes cut hash oils with other oils.[1][2]

Hash oils seized in the 1970s had a THC contents ranging from 10 to 30%. The oil available on the U.S. West Coast in 1974 averaged about 15% THC.[1] 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.[3] The highest THC concentrations measured were 52.9% in hashish and 47.0% in hash oil.[4] Hash oils in use in the 2010s had THC concentrations as high as 90%[5][6] and other products achieving higher concentrations [7]

The following compounds were found in naphtha extracts of Bedrocan Dutch medical cannabis:[8]

The form of the extract varies depending on the process used; it may be liquid, a clear amber solid (called “shatter"), a sticky semisolid substance (called "wax"), or a brittle, honeycombed solid (called "honeycomb wax").[9]


Hash oil is consumed usually by smoking, ingestion, or vaporization.[9] Smoking or vaporizing hash oil is known colloquially as "dabbing",[9] from the English verb to daub (Dutch dabben, French dauber), "to smear with something adhesive".[10] Dabbing devices include special kinds of water pipes ("oil rigs"), and vaporizers similar in design to electronic cigarettes.[9] Some users call their apparatus an “oil rig” that includes a glass water pipe and a hollow metal tube (called a "nail"), with an indentation on the side which is sometimes covered with a dome.[9] The pipe is often heated with a blowtorch rather than a cigarette lighter.[9]


Hash oil is produced by solvent extraction (maceration, infusion or percolation) of marijuana and/or hashish. After filtering and evaporating the solvent, a sticky resinous dank liquid with a strong herbal odor (remarkably different from the peculiar odor of hemp) remains.[1][11]

Fresh, undried plant material is less suited for hash oil production, because much THC and CBD will be present in their carboxylic acid forms (THCA and CBDA), which may not be highly soluble in some solvents.[1] The acids are decarboxylated during drying and heating (smoking). Fresh, undried plant material is best suited for concrete production.

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.[1][8] 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, and will yield a somewhat more potent oil as a result.[1] 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 CBD to THC. Process 1) consists of dissolving the oil in a nonpolar solvent such as petroleum ether, repeatedly washing (saponifying) 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, easier 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.[12]

One pound of marijuana yields from 1/5 to 1/10 of a pound of hash oil.[11] 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).[8]

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.[1] When decolorizing fatty oils, oil retention can be up to 50 wt % on bleaching earths and nearly 100 wt % on activated charcoal.[13]



As of 2015 the health effects of using hash oil were poorly researched.[9]


Most of the solvents employed are flammable, making the extraction process dangerous. Several explosion and fire incidents related to hash oil manufacturing attempts in homes have been reported.[11]

Solvents used to extract THC are flammable and/or combustible and have resulted in explosions, fires, severe injuries, and deaths.[14][15][6][16][17] [18]


The LD50 for THC (Delta 9 Tetrahydrocannabinol) is not exactly known. Hash oil can contain up to 80% THC (wash with alkali) though up to 99% with other methods of extraction. While health issues of the lungs may be exacerbated by use of Hash oil, it is not known to cause side effects not already found in other preparations of Cannabis

Hash oil is not very lipophilic and it may however ooze through and swell common glove materials such as natural rubber, except maybe polar materials such as cellulose film, neoprene and nitrile rubber.


Hash oil should be stored in airtight containers and protected from light. When exposed to air, warmth and light (especially without antioxidants), the oil loses its taste and psychoactivity due to aging. Cannabinoid carboxylic acids (THCA, CBDA, and maybe others) have an antibiotic effect on gram-positive bacteria such as (penicilline-resistant) Staphylococcus aureus, but gram-negative bacteria such as Escherichia coli are unaffected.[19] The effect of hash oil on protozoa, fungi and viruses is unknown.


See also



  1. 1 2 3 4 5 6 7 Michael Starks (1993), Marijuana Chemistry: Genetics, Processing, Potency (2nd ed.), Ronin, pp. 111–126, ISBN 9780914171393
  2. "Cannabis: Overview", World Drug Report (PDF), United Nations Publications, 2014
  3. Marilyn A. Huestis; Michael L. Smith (2007), "Human Cannabinoid Pharmacokinetics and Interpretation of Cannabinoid Concentrations in Biological Fluids and Tissues", in Mahmoud A. ElSohly, Marijuana and the Cannabinoids, Humana Press, pp. 205–235
  4. Rudolf Brenneisen (2007), "Chemistry and Analysis of Phytocannabinoids and Other Cannabis Constituents", in Mahmoud A. ElSohly, Marijuana and the Cannabinoids, Humana Press, pp. 17–49
  5. Gloss, D (October 2015). "An Overview of Products and Bias in Research.". Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 12 (4): 731–4. PMC 4604179Freely accessible. PMID 26202343.
  6. 1 2 "Safety with hash oil". Colorado Marijuana. Retrieved 17 November 2016.
  7. Valerie Vande Panne (21 December 2013). "Hey Buddy, Wanna Dab? Inside The Mainstream Explosion of Cannabis Concentrates". The Daily Beast. Retrieved 3 December 2016.
  8. 1 2 3 Luigi L. Romano; Arno Hazekamp (2013), "Cannabis Oil: chemical evaluation of an upcoming cannabis-based medicine" (PDF), Cannabinoids, 1 (1): 1–11
  9. 1 2 3 4 5 6 7 Stogner, JM; Miller, BL (July 2015). "Assessing the Dangers of "Dabbing": Mere Marijuana or Harmful New Trend?" (PDF). Pediatrics. 136 (1): 1–3. PMID 26077476.
  10. Samuel Johnson (1785), "daub", A Dictionary of the English Language, 1 (6th ed.), p. 541
  11. 1 2 3 Alison Hallett (2013-02-20), "Hash Oil is Blowing Up Across the U.S. - Literally", Wired
  12. Yechiel Gaoni; Raphael Mechoulam (1964), "Isolation, Structure, and Partial Synthesis of an Active Constituent of Hashish", Journal of the American Chemical Society, 86 (8), doi:10.1021/ja01062a046
  13. Alfred Thomas (2007), "Fats and Fatty Oils", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 31
  14. "Dangers of Butane Hash Oil Labs Cited as Five are Charged". US Department of Justice. March 30, 2016.
  15. "Butane Hash Oil Extraction Hazards Issued" (PDF). New Jersey Department of Community Affairs. January 2013.
  16. "Marijuana Butane Honey Oil Extraction on the Rise - Los Angeles County Fire Department". Los Angeles County Fire Department. 19 June 2014.
  17. Romanowski, KS; Barsun, A; Kwan, P; Teo, EH; Palmieri, TL; Sen, S; Maguina, P; Greenhalgh, DG (30 March 2016). "Butane Hash Oil Burns: A 7-Year Perspective on a Growing Problem.". Journal of burn care & research : official publication of the American Burn Association. doi:10.1097/BCR.0000000000000334. PMID 27058582.
  18. Rise in UK explosions linked to super-strength cannabis (BBC News, 2016)
  19. Jan Kabelik (1955), "Hemp as a medicament" (PDF), Acta Univ. Olomuc., 6
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