Decarboxylation

Cannabis produces phyto cannabinoids in a carboxylic acid form that are not orally active at least at the CB-1 receptor sites, because they don’t readily pass the blood brain barrier in their polar form.

To enable them to pass the blood brain barrier, they must first be decarboxylated, to remove the COOH carboxyl group of atoms, which exits in the form of H20 and CO2.

Decarboxylation occurs naturally with time and temperature, as a function of drying, but we can shorten the amount of time required considerably, by adding more heat.  The more heat, the faster it occurs, within reasonable ranges, and in fact occurs spontaneously when the material is burned or vaporized.

There is another mechanism at play however, which suggests that we need to control the decarboxylation temperatures carefully.

When we heat cannabis to convert the THCA and CBDA into THC and CBD, we are also converting THC to CBN at a faster rate.  At about 70% decarboxylation, we actually start converting THC to CBN at a faster rate than we are converting THCA to THC, so as you can see by the following graph, after about 70% decarboxylation, the levels of THC actually start to fall sharply.

That of course means that the CBN also begins to rise and the medication is becoming more sedative.

Thank you Jump 117 for this excellent graph!

Decarboxylation Graph-1-1

Decarboxylation graph

Another fly in the ointment, is that we can never know for sure exactly what the starting state of decarboxylation is, so the times at temperature shown on the graphs are an average.

We can’t expect dry material placed in an oven at any given temperature to be that uniform temperature throughout instantly upon placing it in a heated oven, nor know for sure the state of decarboxylation by simple observation.

Decarboxylating plant material, also alters the taste (roasted/toasted), which some find less agreeable, and of course decarboxylating also evaporates away the smaller Monoterpenes and Sequiterpenes alcohols, phenols, ketones, aldehydes, ethers, and esters.

The good news is that it is dirt simple to monitor the state of cannabis oil decarboxylation placed in a 121C/250F hot oil bath, because you can watch the CO2 bubble production.

Just like the curves suggest, CO2 bubble production will proceed at its own observable rate. By keeping the puddle of oil lightly stirred on the bottom and in the corners of the pot (I use a bamboo skewer), so as to keep the bubbles broken free and floating to the top, you can tell exactly when the bubble formation suddenly tapers off at the top of the curve.

That is the point that we take it out of the oil for maximum head effect, and we leave it in until all bubbling stops, if we want a more sedative night time med.

Here are a couple pictures of what oil looks like when boiling off the residual butane.  Residual butane or alcohol produces larger, randomly sized bubbles, and is fully purged, when they cease.

I am seemingly missing the middle picture of the CO2 bubbles, so I will add it later, but the second picture shows what fully decarboxylated oil looks like.

Residual solvent bubbles above:

Quiescent oil.

595 responses to this post.

  1. Decarbing Frank’s Gift Cannabis

    I’ve been searching for a reliable way to decarboxylate medical cannabis for a while now, and there seems to be no consensus as to exactly how to do it. Different websites and forums all have a different take on the best temperature to use, how long to heat it, how to prepare it etc. My search finally led me to a British patent for a process of liquid CO2 extraction of resin from cannabis, in which they mentioned how they decarbed their samples and, most importantly, they documented the resulting lab analysis of 4 different amount of time and 3 different temperatures, and the differing results on THCa, THC, CBDa, CBD, and CBN. To me, this is a wealth of information. Here is a link to the patent:

    http://www.freepatentsonline.com/7344736.html

    The 3 temps are in Celsius and translate to Fahrenheit as follows: 105° C = 221° F, 120° C = 248° F, and 140° C = 284° F.

    My takeaway from this long, very technical paper is the following 2 sentences:

    Chemovar producing primarily CBD is 1 hour at 120° C. or 0.5 hour at 140° C.
    Chemovar producing primarily THC to minimise CBN formation, is 1 to 2 hours at 105° C. or 1 hour at 120° C.

    Translation: heat your cannabis in a 120° C (248° F) oven for an hour and you are good to go. Regardless of if your cannabis is high in THC or CBD this will work very well. So I did just that (sort of) and then had the cannabis analyzed at OG Analytical in Eugene, OR. Here is what I did, the lab analysis of cured Frank’s Gift bud, and the decarbed Frank’s Gift bud.

    In the patent, they say it is preferable to dry the herb at a lower temp, then decarb it at a higher temp, but since I had put a pizza stone in the oven to try for a more even temp, I dried it and decarbed it at the same temp.

    5/10/16 I started with 36 g total; removed 1.124 g for analytical lab testing. That left @35 g before removing stems, @ 34 g after removing .9 g of stems.

    9:00 AM I put a 16″ pizza stone (9.5 lbs./4.3 Kilograms) in the oven and preheated to 250° F. I used a Farberware oven probe (laying on the pizza stone) to get an accurate temperature. It showed that it took @ 90 minutes to get up to temp.

    I was aiming for a temp of 250° F, but since my oven fluctuates about 20° F, I could not achieve this. After almost 3 hours of screwing around with the oven, turning the temperature dial up and down, trying to get it to a stable temp, I gave up, and settled on a setting of 245° F.

    I broke up the buds into small pieces (it was very sticky), put it on an aluminum baking sheet, and put it in the oven at 11:45AM. I left it in the oven for 20 minutes to dry completely. It was not sticky at all after drying it. I crumbled up the buds in my hand (very easy) and wound up with mostly powdered bud.

    I returned the baking sheet to the oven and waited until the oven probe said 250° F, which took about 15 minutes. I left it in the oven for another hour, removed it, let it cool down a little, and weighed it. It now weighed 28 g, so it lost about 6 g of moisture (17.6%). I took out 1.15 g for the lab. Here are the lab results:

    Before Decarbing

    THCa = 4.8%
    Δ9-THC = 0.9%
    CBDa = 9.9%
    CBD = 0.6%
    CBN = <0.1%

    After Decarbing

    THCa = <0.1%
    Δ9-THC = 4.8%
    CBDa = <0.1%
    CBD = 9.1%
    CBN = 0.2%

    I am thrilled with the results – all of the THCa got converted to THC, all the CBDa got converted to CBD, and very little of the THC got degraded to CBN. Not too shabby.

    Next time I wouldn't mess with the oven temp. I would just set it at 245° F and leave it alone.

    If you look at Table 5 in the patent, you'll see that there is quite a bit of leeway in time before the THC starts to seriously degrade into CBN, so leaving it in the oven for 1-2 hours at 250° F would not degrade very much THC (4.1% after 1 hour and 6.7% after 2 hours).

    Miscellaneous notes: Franks Gift organically grown outdoors, harvested on 10/4/15, dried in 50% humidity, 70° F temp for 5 days (stems snapped at that point), then placed in 2 quart canning jars with a 62% Boveda pack for curing. It has been in the jar for 7 months.

    I hope this is helpful.

    Jackson

    Reply

  2. Posted by SdNative79 on May 14, 2016 at 10:11 PM

    How do I decarboxilate cold extracted bubble hash?

    Reply

  3. Posted by Dawn on May 9, 2016 at 10:33 PM

    I have neuro Lyme Disease it has changed the white matter of my brain I have been deathly ill for almost a decade now from Lyme and other tick Bourne illnesses and was recently bit again and started having all sorts of neuro symptoms. I am sure this article is simple and to the point but my brain isn’t comprehending much of anything since my Lyme went neuro. I need help could you email me and explain this to me in simpler terms and which way would be best for me the head or the sadative. I mean I know I would want the sadative to sleep but which is more healing?? I am having massive headaches, super nausea, vomiting, I haven’t ate hardly any real food since thanksgiving which cause damage me to develop type 2 diabetes it is all I can do to choke down meal replacement shakes. I am so lost. Dawn 1gdgrl6646@gmail.com

    Reply

    • Posted by Dawn on May 9, 2016 at 10:36 PM

      I still haven’t even been able to read my discharge papers from the ER a couple weeks ago. I am completely exhausted. I am terrified of losing more of my brain!

      Reply

  4. Posted by Stephen Weglein on May 9, 2016 at 2:28 PM

    After ‘knowing’ for decades that THC deteriorates to CBN rather easily, and care has to be taken to avoid this …. I have seen here results here that indicate that THC deteriorates to CBN under heat, very very slowly …. is there any reason for this …. or was the degradation story, highly exaggerated, or just wrong? TIA

    Reply

  5. Posted by FeatherMoe on May 9, 2016 at 1:36 PM

    Hi there!

    I made some infused oil in a crock pot and was wondering if the decarboxylation may have happened while it was cooking or I’d I should make a new batch. Cooked on high for at least one day (~270 degrees f) and low for 3 additional days.

    Thank you kindly in advance for your help!

    Reply

    • cooked at 270f for a day? Not only will that be fully decarboxylated but it will probably be degraded too. Why cook it for so long at such a high temp? People either cook for long time at low temp or short time at high temp. You have cooked at high temp for a very long time and I don’t understand what possible reason there is for doing so.
      In short, I would imagine your oil is definitely fully decarbed. In future I would advise you to decarb prior to infusion and also not to cook cannabis oil at such a high temp for so long. There is no benefit to doing so and a lot of detriment

      Reply

    • Posted by Rupi dupi on May 24, 2016 at 11:00 PM

      It may be better to crock pot it on low, around 180 f

      Reply

  6. What would the best way to decarboxylate in order to maximize the conversion of CBDA to CBD?

    Reply

  7. This is amazing! A friend sent me this link out of the blue and I’m a WordPresser too! Can’t wait to see what else you got!

    Reply

  8. Posted by GR on April 28, 2016 at 9:39 PM

    I’m lil confused. Does this method uses oil to extract cannabinoids from plant material? If yes, why butane or alcohol bubbles? I thought those bubbles are CO2 being liberated as result of decarboxilation; not from residual solvents. Thanks, amazing website!

    Reply

    • Posted by Benjamin Goldstein on April 30, 2016 at 11:07 AM

      People first extract the undecarboxylated THC from the bud using a solvent which produces BHO or some other form of extract. Then you can decarboxylate the oil. The bubbles are solvent, usually butane from the oil making process, that is boiling off. Decarboxylation is unrelated and converts THCA (non- psychoactive) to THC (psychoactive). You must decarboxylate bud before making edibles. Grind the bud finely and spread out as thinly as possible. Use the same time and temp the graph calls for,

      Reply

  9. Posted by dave on April 26, 2016 at 4:09 PM

    So i do everclear extracts. Each one has been wildly different and i think the issue is in the way i decarb. Based on this graph im guessing most of my thc is turning into cbn giving me a sedative effect.

    that said, the optimal decarb time and temp to get max thc is what?

    looks like 7 min at 293 F ? can anyone confirm?

    Reply

  10. […] THC and CBD, by a heating or drying process.  I will cover that issue under a separate thread on Decarboxylation, so as to not clutter this […]

    Reply

  11. Posted by Dante Medici on April 21, 2016 at 4:46 PM

    What’s you opinion on cooking coconut oil and sunflower lecithin in mason jars no decarboxylation, vacuumed sealed and put in an immersion circulator at 197.5f for 44 hours then cranked to 200f for the last four hours? Straining when cooled. I feel decarboxylation will occur over the 48 our period. What say you?

    Reply

  12. Posted by Stephen M on April 15, 2016 at 12:56 AM

    I have CO2 and acetone extracted RSO that is over 60% THC, but I want to convert as much THC into CBN. I also have Marinol (pure THC suspended in sesame oil) that would be even better to be able to convert the THC to CBN. The sesame oil smokes before the THC vaporizes, so it can’t be inhaled, only swallowed, which means it is converted from D-9-THC to 11-hydroxy-THC.As far as I know, you can’t extarct the THC from the sesame oil, but if it was converted the CBN, it would be useful for insomnia.

    Any thoughts or suggestions will be appreciated.

    Reply

  13. Posted by Jake Wahl on March 30, 2016 at 12:39 PM

    Is there chart like the one above that follows for BHO decarboxylation?

    Reply

  14. Posted by Lily Kunchak on March 22, 2016 at 3:48 AM

    Hi, Someone can share the decarboxylation graph of CBD (effect of time and tempreture).
    Thank you!

    Reply

  15. Is it ok to decarb BHO in coco oil immedietely before using it in an edible?

    Or

    Should i decarb the BHO seperately then add to the coco oil?

    Thanks for your help.

    Reply

  16. You don’t need to decarb if you are going to smoke or vape because the heat involved in vaporising cannabis causes instant decarboxylation anyway. In fact most people prefer not to decarb cannabis they are going to smoke as 1) it is unnecessary 2) a lot of terpenes are lost which makes it lose taste and smell.
    Decarboxylation is for eating (unless you want to eat the raw cannabinoid acids instead of the decarbed cannabinoids) but not needed if you are going to smoke or vape it

    Reply

    • Thank you for the comments. What could I have done in my process differently to make the oil more potent.

      after freezing everything overnight, I soaked the mj in everclear in mason jar for about 36 hours. I continued the process as instructed to make a tincture. I strained the liquid (mj/everclear mixture) into another mason jar. With the lid off the jar, I placed mason jar with the mixture into a pot of water and heated until the everclear had evaporated/boiled off. I mixed with vg/pg. It has great odor, color greenish yellow. When I smoke it, I feel next to nothing. Please advise

      Reply

      • Posted by Darby on February 17, 2016 at 3:28 PM

        Assuming your quick wash made a full extraction and that is a fair assumption at this point, the biggest variable is how much VG/PG you add. The less you add the more concentrated your vape juice. I haven’t played in this space so don’t know how much to add, if you you want it strong as little as possible to suspend the cannabinoid essential oil.

        Reply

        • so soaking for 36 hours is sufficient?

          Reply

          • Posted by Darby on February 17, 2016 at 3:49 PM

            More than. Look at the quick wash instructions elsewhere on this blog. I would do that, a two pass cold quick wash. Works great and keeps the chlorophyll down. Else do a water soak to clear the chlorophyll first, you can google for instructions. Last option is the lazy man way of letting it soak for 3 months so the chlorophyll breaks down, then filter and evaporate the ethanol. Note all of the above are methods for controlling chlorophyll. All of them do a full extraction of the cannabinoids. (well assuming you are using enough alcohol and I think you are.)

          • Can’t thank you enough.

          • Posted by Craig on March 10, 2016 at 8:32 AM

            U don’t need more than 3 or 4 mins with u mixing it though out then strain it off and evaporate off

      • Well I would personally not use a tincture making method for making oil. It depends what you want as to how best to make it. For example, making a potent oil for eating requires decarboxylation where as making a potent oil for vaping or smoking is best to avoid decarboxylation (as it is not necessary as it will occur from the heat of vaping it anyway).
        If you are making an oil then you should not do such long soaks. Quick wash methods require very brief exposure (QWISO, which is using Isopropyl alcohol should use 30 second washes, QWET which is using Ethanol a little longer, like 1 minute, 2 at most). These quick wash methods give you a very potent and pure oil (golden colour) but not great for yield and you will not get all the cannabinoids from the plant material this way. Alternatively you can do a more thorough wash where you go for 3 to 5 minute washes (closer to 3 for Iso, closer to 5 for Ethanol. The reason for the difference is that Ethanol is slightly less efficient than Isopropyl alcohol at extracting cannabinoids so requires a touch longer, but they work very similar to each other).
        This will give a darker oil that will have more chlorophyll, so will not be as pure and potent but you will get more of the cannabinoids out this way. So your choice in the wash time is between getting more oil but taking chlorophyll too, or getting less oil but much purer.
        But I would never soak the MJ for as long as 36 hours to make an oil That is way too long in my opinion. If you are making a tincture and want everything from the plant then long soaks may be worth considering, but for making an oil 5 minutes is maximum time you want to soak it (and probably not that long).
        Also, if you are smoking the oil then why mix it with VG or PG? Just smoke the oil pure. Such additions may serve a purpose if you are eating or even vaping it but for smoking it is better off being just pure oil. Personally if I want to smoke I just smoke the bud and don’t bother with the hassle of oil making. But as dabbing becomes more popular smoking oil is gaining more interest. But in my humble opinion pure oil is the only wayt to go. There is no point in diluting it.
        I don’t know why you felt nothing. From what you have described you should at least feel something. I know oil makers who make oil for smoking let the alcohol evaporate over the course of days with out heat, to avoid premature decarboxylation. But not sure what else to suggest (aside from shorter washes and not bothering with additional oils)
        Hope that helps a bit. Look at the QWISO or QWET (quick wash) methods for good ways to make nice smokeable oils. If you are not using heat to evaporate the solvent then spreading oil very thin to help the solvent purge properly is a good idea as you don’t want residue (even Ethanol residue) in the oil, especially if you are smoking it.

        Reply

      • It is next to impossible to get a strong enough vape oil by starting with a tincture and diluting it with vg/pg. . You really need to start with a shatter and dilute. 1gram shatter to 2 grams solution will get you high with about 4 hits. Any thicker and you start clogging cartridges. Hope this helps. It took me a long time and a lot of wasted product to figure this out.

        Reply

  17. I am certainly new to all this. I recently tried my hand at making an oil for my vape. I made a tincture with 3.5 g mj and everclear. I did not decarboxylate due to mixed instructions. Some said that the vape process will take care of the process of decarb. I have two questions. Do I need to decarb before making a vape oil?

    I followed the QWISO method on this post:
    https://www.reddit.com/r/vaporents/comments/1sjj1r/four_different_methods_for_making_ecig_juice_in/

    If so, is there any way to recover? I now have about 5 mL of oil, but have not tried it yet.

    Thank you

    Reply

  18. Posted by DropDeadFred on February 16, 2016 at 5:50 AM

    Original poster never updated the second picture, you’re killing me smalls!

    People like me use your genius research as a guideline and if its lacking…we have to guess.

    Help me out, please? I have yet to try a hot oil bath but usually use a 140F water bath followed by a vacuum purge. I think I have been fully decarboxylating it this whole time which may be killing the taste of my dabs… (I thought I was getting ‘all the butane and contaminants’ out)

    Reply

    • You’re right, I failed to follow through, so am lacking, and you are going to have to guess, because my time is limited and I’m unable to quickly find pictures that old in the archives.

      You might give a try just to see if you can tell the difference, because it is pretty blatant and I’ve yet to find anyone who didn’t quickly see the difference.

      Solvent bubbles are random sized and can be quite large.

      CO2 bubbles from decarboxylation, are fine fizzy bubbles.

      Give a shot?

      GW

      Reply

  19. We performed a few experiments to see what conversion ratios of THC to CBN are possible @122C, exceeding 70% decarboxylation. You may be surprised with the results. Check it out! http://www.catscientific.com/decarboxylating-cannabis/

    Steve, CAT Scientific

    Reply

    • Posted by Darby on February 15, 2016 at 3:07 PM

      Very interesting on the lack of cbn production, any thoughts on where over 25% of your cannabinoids went after 6 hours of heating? (Initial total was 23.3 @6hrs total was 17.4)(by the 24 hour mark you have lost over 40%) I think the stronger conclusion is excess time/heat definitely causes a breakdown even if we don’t know into what. Really appreciate both your doing this and your posting it. Would be very curious if you did a similar series for the first 6 hours, to see where total decarboxylation did occur and if there is a sweet spot with regard to total cannabinoid breakdown.

      Reply

      • The analytical lab that performed the analysis told me the THC mg/ml numbers are somewhat inaccurate because the heat reaction is causing other side reactions and other cannabinoid like molecules are being formed. One of them specifically is overlapping with THC in the HPLC system, which messed up accuracy. In order to zero in, he’d have to do a custom analysis developed specifically for the unusual samples.

        Reply

  20. Posted by John on January 24, 2016 at 3:15 PM

    is the process of decarbing CO2 extracted crude oil the same as your posted graph?

    Reply

    • Posted by Al Khemi on February 15, 2016 at 7:53 PM

      I’m really curious why people refer to “CO2-extracted” material as if it were something qualitatively and substantially different from any and all other extracted cannabis.

      I cannot find the sense of it.

      Reply

      • Because it typically is unique, and different. CO2 requires expensive equipment, longer cycles, and close fraction control to produce a purdy, aromatic and tasty extract. Those products typically don’t have the same appearance as BHO or QWET concentrates, to which they are typically compared.

        GW

        Reply

  21. Well I am speaking about decarboxylation and was not making any direct recommendations about solvents, but I see no problem with using Isopropyl as long as it is pure and oil is purged.
    I understand many people prefer to use Ethanol as it is drinkable, but is not as easy to get in pure form in many places. Isopropyl is not suitable for drinking (so obviously should not be used in tinctures) but is one of the least toxic solvents (outside of Ethanol) that you can use (certainly far safer than Hexane and Naptha). In fact its toxicity is not even double that of Ethanol.
    Properly made oil should not contain detectable residue anyway, but small traces of Isopropyl is not considered harmful so I would certainly rather oil makers used Iso than Naptha or hexane (Isopropyl is a class 3 solvent the same as Ethanol and butane, though not as low in toxicity, and is used to extract food grade products often).
    I take it from your comment that you disapprove of using Isopropyl alcohol for extractions. Do you have a valid reason for such concerns (I am happy to listen if you do) or are you one of those evangelical people who thinks using anything but food grade ethanol is wrong?
    p.s. If you do have an issue with using Isopropyl alcohol you may also want to take it up with the admins on this site as they also include Isopropyl as one of the solvents they recommend and even have a guide here on how to make oil with it. In addition to the people involved with this site (who are clearly very experienced and knowledgeable) many other very experienced oil makers use Isopropyl (precisely because it is relatively low in toxicity, easy to get pure in more places and not prohibitively expensive).
    Like I said, if you have constructive criticism or a valid concern regarding the use of Iso then feel free to share. But I am not aware of any valid reason not to use it, especially as many oil makers have and do use far more toxic solvents. With the exception of Ethanol (and some forms of butane) Isopropyl is probably the safest, lowest toxicity, most efficient, effective and easy to acquire solvent available.

    FYI
    Estimated lethal dose for Isopropyl is 8 oz (Ethanol is 14 oz, which is less than double)
    Any form of toxicity requires at least 15 grams (which is way above what would be in even the most poorly purged oils). Unlike Ethanol, Isopropyl evaporates more cleanly and metabolises into acetone (which can then metabolise into organic nutrients) and does not cause acidosis.
    Like I said, it is not suitable for drinking. But is, in my opinion (and the opinion of many others) perfectly suitable as a solvent, especially if oil is properly purged (which should be done regardless of solvent used)

    Reply

  22. Posted by Henrique on January 11, 2016 at 6:19 AM

    I can make butter as follows? Mix the blade with a longer melted butter and bake in a oven at a temperature of 121C / 250F for half an hour? Would not it be more practical than decarboxylate dry first then to make butter? Moreover, not prevent loss by evaporation terpenes?

    (I am Brazilian and I speak English badly.)

    Reply

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