Hexane Honey Oil

Ever thought of using N-Hexane for extraction or alchemy? At the skunk pharm we use an HPLC reagent grade hexane, which we acquire from the local scientific supply store, for a number of things.

Like butane, hexane is a simple alkane, but it has two more carbon atoms and four more hydrogen’s, which makes it completely insoluble in water. Pentane, with five carbons in the chain, is the first completely insoluble alkane.

It’s longer chain gives it a higher specific gravity and higher boiling point than butane. Hexane boils at 69C/156.2F, versus -0.6C/30.9F for butane, which makes it more difficult to purge.

It can be purged under heat and vacuum using thin film techniques, or simply washed in ethanol, which boils at 78C/172.4F.

Our sensory perception threshold for hexane is 30ppm and OSHA TWA limits for breathing it 8 hours, is 500 ppm, so we can detect its gasoline like taste far below TLV.

Hexane is commonly used to produce pharmaceuticals and even food products, and is not Mother’s Milk, but the point is moot, as it is not left in amounts that are toxic.

There is a difference between trace amounts and toxic doses, because poison is in the dosage. Even Oxygen is a toxin at over 75% atmosphere and you are just as dead as from an over dose of any substance.

So what are the facts about hexane? One is that if hexane is present at levels as low as 30ppm, it tastes exactly like gasoline.

Since concern starts at 250 ppm for chronic and nearly continuous exposure, our senses are adequate to protect us from exposure to toxic levels.

So lets see what the governing authorities think about it, while paying attention to how the dosage rates compare to levels less than 30 parts per millionth:


CAS# 110-54-3: MN9275000
CAS# 110-54-3:

Draize test, rabbit, eye: 10 mg Mild;
Inhalation, mouse: LC50 = 150000 mg/m3/2H;
Inhalation, rat: LC50 = 48000 ppm/4H;
Inhalation, rat: LC50 = 627000 mg/m3/3M;
Oral, rat: LD50 = 25 gm/kg;


CAS# 110-54-3: Not listed by ACGIH, IARC, NTP, or CA Prop 65.

Epidemiology: Occupational polyneuropathy has resulted from hexane exposures as low as 500 ppm, but the minimum levels of n-hexane that are neurotoxic in humans haven’t been established.

Nearly continuous exposure of animals at 250 ppm has caused neurotoxic effects.

Teratogenicity: No evidence of teratogenicity or embryotoxicity in anmial studies with hexane.

Fetotoxicity has been observed in the presence of maternal toxicity.

Reproductive Effects: Severe testicular damage has been observed in rats exposed to hexane at concentrations which have produced other significant toxicity.

Although sub-neuro toxic doses of its principle toxic metabolite, 2,5-hexanedione, can induce progressive testicular toxicity in rats, there have been no reports of human sterility or other reproductive toxicity associated with n-hexane exposures.

Mutagenicity: Positive results (chromosomal damage in the bone marrow cells) obtained for rats exposed by inhalation to n-hexane.

Neurotoxicity: n-Hexane is a mild irritant and CNS depressant in acute exposure, but its principal effects are damage to the sensory and motor peripheral nerves, particularly in chronic exposure.

Moving to ease of use, because of its insolubility in water, you can soak plant material in hexane without picking up water solubles.  I have soaked as long as 12 hours.

Using hexane requires close attention to safety issues, as it is highly flammable and even lower explosive limits than butane when used in an unventilated area.

Hexane’s lower explosive limits is 1.2% of atmosphere, and its upper explosive limits are 7.7, as compared to lower limits of 3.3% for ethanol and 1.8% for butane. Except for well ventilated lab conditions, hexane extraction and alchemy is best done outdoors, with a fan blowing away and dispersing the vapors as they are given off.

Pentane and Hexane are the components of light naphtha, or white gasoline, and should be treated with the same care and respect.

Needless to say that it a no smoking or toking activity, so leave the lighter and smokes out of reach, lest you reach for them automatically.

Besides open flame, static sparks can ignite the fumes, so don’t do hexane extractions wearing plastic clothes, especially on cold dry days.

Using glass wear to contain highly flammable liquids carries drop and splash dangers, which I am going to draw your attention to, but confess that I routinely use lab glass wear with flammables in it and that the hexane itself usually comes in a glass jug.

A stainless steel container for the soak portion of the process, could achieve the same effects however, without the same breakage danger.

Ambient temperature is important, and hexane has a relatively high vapor pressure of 151mm Hg @ 25C/77F, so it is important to keep the mixture relatively cool for long soaks or use a vented container to control pressure buildup.

We use hexane for both extraction and cannabis alchemy. Because it is relatively expensive, it is usually more cost effective to do the initial extraction with another less expensive solvent and use a lesser volume of hexane to polish it afterwards.

For extraction we simply fill a jar about 2/3rd full of material that we have broken up to about coarse rolling size, and fill the jar to the 3/4 level with hexane. We shake well, loosen the lid to release the pressure, seal it again, and set aside.   We periodically repeat the shake and pressure relief steps, for up to 12 hours.

At the end of the soak, we pour the mixture in a strainer, and press the material to force as much hexane out of the plant material as possible. We then filter through a coffee filter or vacuum filter using a Wattman # 1.

You can do the initial purge of the hexane by simply setting it aside in a pie plate to evaporate, and can speed that up by setting the pie plate in hot water and blowing air over it, if you aren’t in a dusty setting.

You can also boil off the hexane in a double boiler, with either hot water or hot oil as the medium in the pot, and can speed that up with vacuum. See attached pictures of thin film vacuum purging, as well as a ghetto rig in a fruit jar:

That brings us back to final purge, and as I noted above, if you don’t have vacuum equipment, final purging can also be done by washing in ethanol. Washing is done by re-dissolving the raw HHO in ethanol and boiling the ethanol off. The higher boiling point of the ethanol and the scrubbing action of the alcohol molecules boiling off, will take the remaining hexane molecules with it, while keeping the process temperature below 173F.

Re-dissolving in ethanol also allows the interim step of winterizing, by which you place the ethanol HHO mixture in the freezer for a couple of days until the waxes coagulate and can be filtered out, before evaporating away the alcohol.

While it can be used for extractions, where hexane really shines, is cannabis alchemy. For instance, you can extract the cannabinoids with ISO, Methanol, or Denatured alcohol and after reducing the volume of the alcohol through evaporation, when it reaches a convenient and economical handling volume, mix it with equal parts of hexane and super saturated salt water.

If you agitate that and place it in a separatory funnel to separate, the hexane will rise to the top with the cannabinoids and the water and alcohol mixture will sink to the bottom, where they can be bled off. See picture of separatory funnel, and check out our page on polishing extracts for more details.

Lastly, we use hexane to isomerize or make cannabis acetate. That involves reflux boiling the hexane cannabis oil mixture in sulfuric acid, or acetic anhydride.

More on that in Joe’s Cannabis Acetate thread.

171 responses to this post.

  1. Posted by Onlysurvivor on September 26, 2015 at 7:09 PM

    GW, Thanks for all the REALLY helpful information, you guys must have a great time doing what you do! I was going to use the term “blast” but thought otherwise. My question(s) have to do with cold boiling, purging and recovering as much of the solvents used (Hexane and Ethanol) at room temperature as described below and if this process will work. You have much more experience so we look to the “Master” for his opinion.
    A friend sent me his “recipe” for HHO. It seems very straightforward and clear process.
    This process seems slightly safer than boiling under heat since it is performed at “room temperature”, I guess the area is hot since the stated temp is 21c or 80f.
    If there are any missed steps or critical errors PLEASE ADVISE. Would you please review it as I would like to try it ASAP.
    Here is the process as explained to me:

    Materials List:
    112g of high grade dry (40% humidity) bud
    1 Liter of HPLC Grade Hexane 98%+
    1 liter of 95% Ethyl Alcohol
    1cf Vacuum Oven or vacuum chamber (since heat is not required)
    1000ml vacuum distillation kit and stand to hold it.
    70mm Ceramic Buchner vacuum filter kit and slow 70mm filter paper
    Vacuum pump, Vacuum gauge(s),
    Submersible fountain pump (small), air tubing, 5 Gal bucket
    20Lb Ice
    2 big mason jars with lids
    gloves, goggles, lab coat, assorted glassware
    Lots of Isopropyl Alcohol and paper towels to clean up
    A work Area with plenty of ventilation (OUTSIDE), no source of ignition or flame

    1. Grind the material to the consistency of course coffee grounds, remove any sticks and twigs.
    2. Soak Material covered in Hexane for 12 hrs in a Stainless or glass container semi-sealed and allowed to release the pressure. I put it in the fridge to minimize evaporation. Mason Jars work fine just don’t tighten the top.
    3. Vacuum filter the soaked material through “Slow” filter paper (you can cover the top of the filter funnel with clear plastic food wrap and a rubber band which will increase the vacuum pressure as the plastic food wrap is pulled down adding pressure to the material getting more of the liquid out), save liquid. If any solid material is present in the liquid repeat step 3 until there is no vegetable material present.
    4. Take the filtered bud material and repeat steps 1 & 2 again, 2 runs should be sufficient if you have enough Hexane left or use the recovered Hexane. If you repeat the process and distill each hexane extraction individually you will see that the first extraction gets about 98% and the second gets very little but one pass doesn’t get it all and we would hate to throw away any of the good stuff.
    5. WINTERIZATION; Mix filtered Hexane with equal amount of 95% Ethyl Alcohol and Place the filtered liquid in Freezer for 12 hrs and allow the waxes to congeal. You can place it in the freezer in a bath or bag of dry ice to reduce the temperature as much as possible (**do not place dry ice in the liquid) Time and temperature are key so, as cold as you can get it works best (-50) but most freezers give up long before that. It takes time for the waxes to congeal enough to filter them out, that’s why the 12 hours.
    6. Vacuum filter the liquid again through slow filter paper ** We Freeze our ceramic Buchner filter prior to vacuum filtering the waxes, as they will melt back into the liquid so keep the funnel as cold as possible during this step. Keeping it really cold is really good in this process so colder the better. Allow the waxes after filtration to air dry and they can be used in hand cream or other uses
    7. BASIC FRACTAL DISTALLATION: Place the now filtered liquid into a distilling flask of sufficient size and connect to the distilling column with the thermometer in the liquid, it will take a while for it to come up to room temperature (21c 80f).
    8. Once the mixture reaches room temperature, Vacuum distill the Hexane off at room temperature (21c) at 22 In. Merc. On my Gauge, either by maintaining the vacuum pressure or the temperature the Hexane should distill off long before the alcohol, if you keep this a constant. This can take awhile depending on the volume. **Measure the distilled Hexane to make sure you got MOST of it. ** I have a 1000ml vacuum distillation kit I bought on Ebay with 2X 1000ml boiling flasks, 1x 300mm Liebert condenser, a few fittings, to which I added a 300mm Graham condenser in series to the Leibert condenser being first in line. I feed chilled water from the bottom to the top of the columns using a small submersible fountain pump in 5 gallon bucket filled with ice and water that recirculates. Place a collection flask just past your vacuum port in an ice bath and turn on the pump to controlled vacuum pressure. Save the re-distilled Hexane to use on the next batch.
    9. Once you recover the majority of the Hexane, change to a clean flask and raise the vacuum to pressure 28 In. Merc. And the alcohol should start distillation, this will also remove any lingering Hexane. Recover as much of the alcohol until the oil mixture starts to noticeably thicken.
    10. THIN FILM EVAPORATION: Remove the liquid into Pyrex baking pan(s) putting NOT more than ¼ (.25) inch of liquid into the pan, cover with glass flat sheet to prevent it from boiling out of the Pyrex (these can be stacked in the oven, we use 4) and place in vacuum oven (no heat) and apply vacuum SLOWLY to 29 In. Merc. and the balance of the alcohol will boil off. Repeat the filling and purging process if necessary until all the liquid is evaporated and you have a thick oil remaining, if after an hour there is no more alcohol dripping into the cold trap or condenser then all the alcohol has been purged.** Make sure you have a cold trap connected between your oven and pump or connect your oven to the distillation column before pulling a vacuum (this is what is recommend, using the same columns and ice bath to recover any remaining solvent(s) with the distillation apparatus). **Hexane and alcohol will ruin the oil in your vacuum pump and stink up your work area.
    11. Test the Oil in the oven, If you can still taste the Hexane after step #10 when smoked, redislove the oil into fresh 190 proof Alcohol and purge in the oven again until the Hexane (Gasoline) taste and alcohol are gone.
    12. Never pull a vacuum on the oil mixture higher than 29.8 (at room temperature) or the cannabinoids will start to boil off as well(17c/68f @ 29.9). 29.8 is a lot however and many pumps will not go this far (29.5 max) but will easily get to the pressures necessary to vacuum distill and vacuum purge water or solvents.
    **Always Increase the vacuum pressure slowly, rapid decompression has the same result as increasing the heat rapidly and can result in the mixture boiling out of control. To stop the boiling simply stop or reduce the vacuum. **Always “lock off” your vacuum pump with a valve as they can “bleed” vacuum oil back up your vacuum tube (liquid or airisol) and into your PURE product when they are shut off and connected to a vacuum.

    We recovered 22g of pure oil or about 19.6%, no hexane taste, no waxes just clear thick oil. We recover about 97%+ of the solvents also. If you purge and distill reasonably carefully you can easily reuse your solvents.

    If your alcohol starts to smell like gasoline, there’s a lot of Hexane in it, probably just start with fresh as the “gasoline” taste is what you are trying to get rid of, this is a result of incomplete purge of the hexane stage, to fast or too much vacuum pressure, the boiling point of Hexane and Alcohol are quite different and can easily be separated, The amount of Hexane necessary to be able to be detected by smell is small and taste even smaller(>130ppm or less, target is >30ppm or less).

    This process will yield good high quality Oil if you take your time. The shortcuts through this process are expensive and don’t really impact yield or quality very much. Sure, you could add lots of equipment and cost but you will not get much cleaner or better product.


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