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BHO Purging Method

Discussion in 'Concentrates & Processing' started by Default 501x, Feb 11, 2011.

How do you purge?

  1. HmK method - 30 mins-1hr in a hot water bath

    50 vote(s)
  2. low heat overnight purge

    13 vote(s)
  3. hot water purge then vacuum purge

    61 vote(s)
  4. other

    27 vote(s)
  1. Jsän



    hey bud, "the blast' they are talking about is during the actual extraction of the oil. the butane fills the tube, it stalls for a minute as it collects, then starts blasting out of the filter... its cool to see.

    if you wish to repurge, yeah just melt it in some hot water. let stand till there are no more bubbles.
    EDIT : LID OFF!! never heat an enclosed glass vessel.
    if you are planning to cook with the BHO, may i suggest while it is still liquid from repurging you infuse it to some Olive Oil.
  2. pandor


    Thanks for the reply. I have so found very little knowledge for noobs out there who want to start cooking with BHO. One thread I have on another site has sat for weeks with no reply. This is why I am going to start using this as my main site.

    So, set up the jar with the BHO in boiling water. Can the jar just sit in the pan, or do I need to suspend it somehow so the bottom of the jar is not hitting the bottom of the pan? Does the water need to reach a certain temp? How will I know if I have purged enough to make the BHO edible?

    Once the purge is done, how would I go about adding the olive oil? Is there a technique? I only have a few grams of the BHO for now, but I know there is plenty more available to me if I can just learn how to use it.

    Thanks so much.
  3. Jsän


    sorry farmers. should of started a thread

    heres what i would do.
    heat some water to boiling in a tea kettle.
    place your bottle of BHO in a tea cup. Top off of the bho bottle.
    add just enough water to heat things up.
    as it liquifies, begin to stir the bho gently.
    once the bho has fully melted, replace the water with fresh hot water, keep stiring.
    Observe. are any bubbles forming? keep stirring. Butane boils and evaporates at room temp. give the bho a sniff... does it smell 'chemicaly?'
    if no bubbles are forming, no butane smell after a few minutes of heating,passes the flame test?
    the bho is purged. keep it in the warm water and bring some olive oil to temp.
    in a seperate cup, add about some olive oil and about a gram of BHO
    start stirring.
    they will mix eventually, time is dependent on the BHO and olive oil so i cant really give you a time frame.
    add more olive oil if the mix starts to cool.
    add more BHO as the two start to mix.

    remember to always start small. some strains BHO seems harder to marry to the oil than others. if it is being stubborn, slow cooking in a crockpot/double boiler or even a coffee pot element should bring it along.

    some places heat their oil mix for as long as 5days.
    after all the oil is dissolved into the olive oil
    let cool a bit then add a light dusting of lecithin.
    it is optional, but it increases the cannabinoids bioavailability.

    good luck bro.

    PS. this is 'dressing oil" not for regular cooking. always add thc oil last to a dish to keep the goodies from cooking off.
  4. What if?

    Disclaimer: I am an organic chemistry graduate student.

    What I'm sharing with you are observations and suggestions based on a few hours of reading on the topic, a basic understanding of the chemistry of cannabis, and several years lab experience in purification processes.

    I am by no means a Dr. of chemistry and do not purport myself to be, however--I have gained a reasonable amount of knowledge on the subject and may have some insight to add. What I can say is that I know what I'm suggesting won't destroy the target chemicals. The method may require some tweaking, but ultimately none of these concepts should be super unfamiliar to you.

    That said:

    For any of you guys doing this. I'd be interested to see what the results of the following procedure would be.

    1. Extract as usual, with an added caveat that you should keep the butane/oil mixture hot as it is being eluted into your container ("blast" into a container over a boiling water bath or pre heated heating element--No flames or sparks obviously).


    Your best chance to prevent what are called "inclusion" or (if they are larger sized) "occlusion" impurities when "working up" (removing solvents/purifying/isolating product) a reaction involving production of a viscous oil is to control the viscosity the oil can attain as the impurities work their way out. For a lot of mathy reasons this is the best place to increase the efficiency of your removal of butane.

    This step alone (with some optimization) might increase the efficiency with which you remove butane significantly. I can't say what the best temp will be without knowing specifically the viscosity of BHO and other factors.

    Here is where my proposed experiment deviates from the standard (or at least what I've read in the past few hours):

    2. Dissolve the the BHO in the highest grade ethanol (EtOH) that you can find. The mixture should be homogenous, and have low, water-like, viscosity.


    I choose ethanol because it dissolves the target chemicals and is much safer for consumption than butane in general. If you are concerned that butane is bad for your health and should be purged, you may be best suited to all but remove it completely by driving it out with an excess of another solvent. Furthermore, butane has a higher affinity (through intermolecular interactions) for the target molecules according to information I can find than does ethanol. This makes it more likely, on evaporation, to "include" itself as micro-droplets in oil. You might say, well why not just use ethanol for the first extraction? The answer is because it tends to extract more unwanted molecules from the plant which butane excludes. In effect the extraction tube you guys are using is a column chromatograph, the added dimension of slightly higher pressure created by the butane rapidly expanding is actually beneficial in this. Read up on how polarity affects column chromatography and you will understand better why butane is getting out more of what we want and less of what we don't. In any case butane's high affinity for the target is beneficial initially. Now that we have reached this step of the purification process its utility is greatly diminished due to this same property, as it will tend more to include itself in the oil.

    3. Heat the resulting liquid with vigorous stirring and a fan blowing into the receptacle for ventilation. I must strongly recommend you use all due precaution for ventilation and avoidance of exposure to flame during this step. A good minute or two of this with the liquid brought to sufficient heat (hot to the touch is more than good enough) should be enough to drive off any excess butane.

    4. evaporate the alcohol using any number of methodologies easily looked up and collect oil.


    You may vacuum purge this if you like, but you will need to reconsider optimal pressures and temperatures.

    Several cycles of heating to a molten state and cooling will help to drive off excess EtOH in absence of a purge. Stirring during this process will help tremendously.

    In closing:

    The reason I suggest this process is that, for this application and with readily available equipment, it will be impossible to remove all butane by any other method. Across the web I see much talk of which method will really remove ALL the butane. The answer is, sans a lab, training, and a painful sacrifice to yield--none of them.

    Realistically the solvent system available for this extraction is terrible--no chemist would extract these chemicals this way. However, without proper training it is dangerous and borderline unethical to suggest using anything else to perform it. Some of the stuff I've seen on the web, fuming sulfuric acid for one, can be fatal if mishandled.

    Truthfully, if I had my way--everyone would be using hexanes to extract and then performing water washes to remove impurities which are likely to contribute to the inclusion of solvents in products. Subsequently hexanes could be driven off using the above described method. I believe this would greatly increase purity. Hexanes has an even higher affinity for THC than does butane which helps with initial extraction as well.

    Ethanol is not as toxic as butane--and though its not awesome to smoke still, its significantly better than imploding a mason jar in your kitchen to the sound of your screaming wife.

    Smoking even trace amounts of butane over and over and over again may do tangible damage over time. According to what I can find the same is true for ethanol, but it is less true. All of this must be taken in context, though, you could inhale butane as a hobby and never have complications. Or inhaling it once in your life might give you cancer, chemistry is funny like that.

    Let me know if you have any questions on what I'm getting at, or how to set up a control experiment to test results.
  5. Jsän


    The problem with using Ethanol as a solvent as i see it, is availability.

    Here in the states it is illegal to distill your own spirits.
    and Store bought alcohol's have many different chemicals not listed.
    Binders, fillers and polishers.
    Even that bottle of 90proof of Everclear has harsh unnamed chemicals.

    check the specific gravity on any store bought liquor to see what i mean.
  6. sfzoo


    if I had access to hexane, how would the extraction be done? quick wash like iso then evap as you've described?
  7. Most people who are performing these extractions, I'd guess, are doing so illegally. I may be wrong about that when it comes to state law, but federally just possessing an extraction tube with any residue constitutes many serious offenses.

    That said, a distillation apparatus (and knowledge on how to use one) can be had quite easily/cheaply. However (for beginners), distilling ethanol can be VERY dangerous if precautions are not taken. No flame should be used in this process, regardless of shielding from the reaction atmosphere or ventilation. Please also remember NEVER to heat a closed reaction system.
  8. Hexanes Extract

    I would actually use a tube system--just like the butane extraction without the pressure. Pour an amount of hexane(s) through the tube which is equal to the amount of butane you usually use per gram. Best results will come from consistent addition of solvent and steady solvent flow through the tube.

    Shake should probably be used for the most complete extraction. The benefit of using hexanes is that it is a liquid at RT (though it is still volatile), and it is not miscible with water. Thus a sep. funnel or a reasonable McGuyver version will allow you to wash the extract with water. Use a volume roughly equal to that of the organic solvent/extract mixture--and repeat 2x. Wash the organic layer a 3rd time with a brine solution (saturated NaCl/H2O solution) to leech out as much water as possible from the solvent layer. If you have access to drying agents (MgSO4 and the like) now is a good time to dry the organic layer over one.

    If you used a drying agent filter the mixture into an evaporation medium and wait. Use lab quality filters for this, NOT coffee filters.

    Once evap has completed you may vac purge, or use ethanol as above to fully remove hexanes from the mixture. A bit more heat, and a little more time stirring will be required than with butane.

    A few quick notes. Do not simply wash the organic layer with all volumes of water simultaneously. The removal of impurities operates according to an equilibrium. Washing the layer with two separate volumes greatly increases the effect. After about 3 washes diminishing returns are in full effect and you're not pulling much else out.

    For the a more advanced, careful pH precipitation and removal of impurities may be carried out in the sep funnel. Purification by this technique (with many different variations obviously) is the basis for nearly all industrial chemical purification processes and represents a much more reliable way to end up with a "pure" product.

    Another step to remove impurities would be to treat the extract solution with activated carbon and filter. This will really clean the stuff up. I am unsure what the effect will be on other desirable chemicals (i believe it will leave them alone as well), but it will not bind to cannabinoids strongly. An extra volume of solvent may be poured through the filtrand (the activated carbon mass left in the filter) to ensure all chemicals we want have been eluted.

    I want to be clear that your mass yield should drop from this, but theoretically your yield of target compounds should increase. This is obviously what we expect on further purification.
  9. i believe the process you described is actually exactly what the Tamisuim extractor goes through in its butane recovery process. to the best of my knowledge it uses ethane as a secondary solvent to remove the bho from the initial collection chamber, then recycles the butane and leaves you with just the ethane to boil off.

    the main problem i have with alcohol is that it is honestly SO MUCH EASIER for me to get close to pure elemental butane with no additional chemicals in it than it is for me to get to pure ethanol or any other form of alcohol.

    id really love to see what kind of results come out of this process though.

    final thought- you say no chemist would extract chemicals this way, i have to contest this, as i went on a tour of a soybean oil manufacturing plant and unless i missed something major i saw that the process is almost identical, just on a much larger scale, and with different solvents.
  10. The use of different solvents is what I'm referring to when I say no chemist would use this method. I mean no chemist would use this solvent system--it is terrible for what the goal of this process is.

    Realistically if we're talking getting pure THC, you're going to have to solubilize the THC--which requires changing its chemical structure. Then you would purify it using a sep funnel methodology as above. Then you'd reverse the process to give the oil.
    Skoosh likes this.
  11. Hashmasta-Kut

    Hashmasta-Kut Moderator Staff Member Supporter

    it is not terrible, its about the best solvent there is. we dont want pure THC, we want as much terpenes as possible as well, and butane as been proven to capture the most flavor essence(terpenes).
  12. jump


    After dissolution BHO in ethanol apply the winterization, ie alcohol solution to cool to -20C, and cold filtered to remove waxes and fats from the extract,

    the extract was produced and purified in this way is called absolute.
  13. Looks like this thread has wandered a bit, so I will stray some too.

    We currently purge BHO under 29.9" hg vacuum, while keeping the pool molten around 120F using gutter heat cables wrapped around the bottom of the vessel.

    We wash that out of the collection vessel with hot ethanol, and freeze that overnight to coagulate the waxes, which we filter out before evaporating away the alcohol by either distilling it off with heat, or in a thin film under 29.9" vacuum.

    For oral consumption, we do a final purge in a 250F hot oil bath, and leave it in the hot oil bath until it is decarboxylated, as witnessed by the CO2 bubble formation and dissipation.

    We weigh the tare of the container that we are processing the oil in, and as soon as it is decarboxylated, we wipe the oil off of the container and weigh it again to determine ending oil weight.

    Subtracting the tare, we add the rest of the ingredients at that point and set it back in the hot oil bath. We stir until it is thoroughly mixed, and then decant into the bottles.

  14. I agree it gets the job done--however, I keep hearing the word pure. In terms of reaching a goal of purity this solvent system is far from ideal. I imagine there is a better solvent which will also pull out the terpenes, to give "a pure mixture of cannabinoids and terpenes."

    The big problem here is that, scientifically, there's no such thing as a pure mixture which has been extracted--there's simply no way to attain a "pure mixture" without first isolating products and then mixing them.

    I would assume that CH2Cl2 would work wonders for this extraction.

    If a chemist were to do a wet extraction of this material without pressurized equipment they would simply not use these solvents--ever. (They wouldn't use ethanol either, this is basically a rule!). When they would use butane is under pressure, as the person before stated is the case in the herbal extractor.

    I'm fairly certain a chemist using the equipment you guys have would use either hexanes, chloroform, or methylene chloride to perform the initial extraction. With methylene chloride probably being the easiest for this application (if we want speed) as it has the lowest boiling point yet is still mostly liquid at RT.

    Chemists just don't use gases at atmospheric pressure to perform extractions at atmospheric pressure. This property of the butane, while it seems to make the process easier (time-wise), actually presents a load of issues when it comes to impurities..
  15. You may skip the first vac purge if you are using hot ethanol to extract the oil from the collection vessel. This step (with additional heating and stirring) will purge butane on its own as ive described in my previous post. (This is really the main help I was attempting to provide)
  16. Sorry for the double quote, but it should also be noted that whatever butane will pull out--hexanes should pull it out better/faster (quicker time of elution). The only real question i have as to whether or not hexanes will be better is if terpenes are water solubule--common knowledge would have to tell me that they most likely are not, though. This really brings up the utility of having a liquid solvent if it is the case. If its pure terpenes and cannabinoids you're after then you will not get closer than you currently are without washes in some kind of sep funnel.
  17. Thank you for your sage advice SQ!

    That is in fact how we used to make ours, until we developed the ability to do a hard vacuum purge at low temperatures for both butane and ethanol.

    As you note, no butane was ever detected in any of our oils after simply boiling off the alcohol, so we are perhaps gilding-the-lily, but not everyone wants decarboxylated medications, so we also developed cold boiling processes.

    While it may be egg-in-the-beer, it takes about a minute to pull it to that level of vacuum with our 6.2 CFM high vacuum pump, once the butane has been pulled off by the recovery pump.

    I am not a chemist either, and alas, old habits die hard, or maybe even not at all since I passed dotage!

    As a long retired aerospace manufacturing and process engineer, I struggle with the concept that from a quality control standpoint, assuring better than 6 sigma perfection at each step in the process, makes it easier to achieve 6 sigma perfection in the end product, when all of the screw ups add up
  18. We also use hexane and it should be noted that it is harder to get rid of in the final purge. Here is where we still use boiling in ethanol to get a final purge.

  19. if you don't mind me getting a little off topic to ask this, what is the difference between the errls that have and have not been decarboxylated during the purge? for people who are actually smoking them and not orally ingesting, does a low temp hard vacuum purge make a big difference versus a normal temp?
    I'm just curious because when i've seen waxes made with the same method i use (hot water->hard vac @ around 100F) tested they always have some percentage THCa and some THC, some favor highly towards the latter while the ones favoring higher temp purges are far more THCa and i've often wondered if that meant my purging method was affecting potency somehow.

    /offtopic sorry!
  20. The non decarboxylated oil has slightly more head effect when vaporized or smoked and less sedative effect when over done. It also has more turpenoid flavors.

    The oil also has less viscosity once decarboxylated and seems to produce slightly less cough.