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.

288 responses to this post.

  1. Posted by Joe C on July 24, 2014 at 6:43 PM

    Ive been searching the interwebs in order to create a specific oil to aid a family friend with type 1 diabetes… From what i can gather, CBN is what i’m trying to amplify. With that in mind & based on the fact TCH converts to CBN if decarb’d longer, how long would you leave it @ 250 – 270 F ?? Cheers, Joe


    • Posted by Kyle on July 26, 2014 at 2:47 PM

      Just a thought, but you may be able to find pure CBN extracts online since this isolated chemical isn’t scheduled. I know a friend of mine was able to order big syringes full of CBD oil from amazon.


      • Posted by Joe C on July 27, 2014 at 4:56 PM

        I live in AUS so i’m not sure the same applies here, but will look into it. Also i’ve heard that CBN alone is not the best as one also requires the many other components of cannibis plant. Correct me if i’m wrong as i’m a cannabis oil noob!


        • Posted by Kyle on July 27, 2014 at 5:45 PM

          According to that chart after about 4+ hours at ~260 degrees F there would be very little THC which would imply that the THC has mostly converted to CBN. You could also look up the temperature at which CBN is destroyed. If its a much higher temperature you could keep heating for even longer maybe to get an even higher yield of CBN. Just a thought.


  2. What about bubble hash, how could you monitor it’s decarb. rate? Just by color or is there a more specific way of judging it’s percentage of decarboxylation? I feel like over-heating and surpassing the 70% might be a big problem in most edible makers recipes at the moment, or at least I’ve personally noticed a lack in potency with hash infused edibles. What’s different about the process with a water extract versus chemical?


    • Posted by MattMatt on July 21, 2014 at 6:16 AM

      It is harder to judge when Hash is finished decarbing, same goes for plant material. Oil you can tell by the bubbles. Hash I wouldn’t know. I think if you cooked it for between 30 to 60 minutes at temps between 110 and 130c then you are pretty certain to get your hash decarboxylated to a near full degree with out too much over cooking. But the precision is easier to gage with oil because you can use the activity as an indication of decarboxylation.
      Water extractions are generally less efficient that solvents because THC is not water soluble so it is not actually dissolving into the water, it’s more like just being washed off in a more crude manner. Solvents that require heat to boil off will result in some partial decarboxylation, where as cold extraction solvents like Butane will not result in any decarboxylation, but both methods require additional cooking. As for cooking hash or plant material, the best you can do (to my knowledge) is cook it for the appropriate times and temps and hope that decarb is achieved with out too much overcooking.


  3. Posted by JLVanta on July 11, 2014 at 2:43 AM

    Incredible stuff on this site! Love it!

    I have some questions as a newbie, I have seen many videos starting from the original RS Video, to this one I found on a Dutch site quite impressive and easy for everyone to do…

    None of them decarboxylat the oil and its seems to work anyway…

    Some Chemical Phd said that while decarboxylat translates your THCA CBDA –> THC CBD…it also destroys or decreases (partially or completly dont know) the other good stuff…to name a few (tetrahydrocannabivarin, myrcene, caryophyllene, d-limonene ,linalool, pulegone,cineole ,a-pinene,a-terpineol,terpineol-4-ol,p-cymene apigenin, quercetin, cannflavin A etc..)
    I am really sorry for not providing a link to thois theory, because I lost the bookmarks, so do you think that there is some thruth about it?
    I want to make some oil for my Mother with Chronic Pain, would like to do it right…

    Thanks to all!


    • Posted by MattMatt on July 11, 2014 at 10:37 AM

      It is true that many of the terpenes (d-limonene, linalool, mycrene, a-pinene etc.) are evaporated off when you decarboxylate cannabis oil, and obviously all the cannabinoid acids are lost as they are converted to the neutral cannabinoids. However it is the neutral cannabinoids that are most important for treating many conditions, especially cancer.
      Terpenes can be sourced from other plants as they are present in many things. Citrus fruits contain d-limonene for example, Linalool is in mint and cinnamon, Myrcene is found in thyme and lemon grass. So you could make other extracts for terpene content if you wish to supplement the cannabis oil.
      Another option chosen by many is to make both raw and cooked cannabis oil and take both so that you can get decarboxylated cannabinoids from the cooked oil and cannabinoid acids and terpenes from the raw. The video from the link you provided did involve some heat so would likely have been partially decarboxylated. Partial decarb is also something that people opt for as partially cooked oils contain activated cannabinoids and cannabinoid acids, along with whatever terpenes remain.
      Personally I think you are best either cooking oil fully or leaving it completely raw and simply taking both if you wish to utilise both, as oppose to partial decarboxylation. As partial decarb is harder to dose as you don’t know how much decarboxylation has occurred. Where as if you have fully cooked oil you can dose it more accurately and then take raw oils as a supplement to the treatment.
      For chronic pain I honestly do not know which is better, so maybe someone else could advise. Cooked cannabis is definitely better for cancer as the actives cannabinoids like THC and CBD are far more effective against cancer than cannabinoid acids or terpenes. And I would expect decarboxylated cannabis to be better for chronic pain, but I have heard that many people have found raw to be better for chronic pain. So you might need to try both and see which works best.
      For most conditions, including cancer, the most ideal scenario is to have large amounts of both raw and cooked cannabis oil. But for most people access is limited and choosing the optimum for their conditions is necessary. As I said for most conditions cooked cannabis is more potent, but there are some conditions that respond better to the cannabinoid acids and some patients who have reported better relief from raw.
      So for your mother you may need to experiment a bit and try her on both. She will be able to take much larger amounts of raw oil with no psychoactive effects, where as cooked will require her to start with very small doses and slowly build up a tolerance.
      Like I said if you go for fully decarboxylated and wish to add some terpenes to make up for what is lost then you can make other extracts for terpenes or add things like turmeric, citrus fruits and ginger to her regime.
      Hope this is of help to you.


      • Posted by margaret on July 29, 2014 at 11:22 PM

        If the oil was made a few days ago and one wasn’t sure if it was properly decarboxylated can u put it in the oven days later and decarboxylate?


        • Posted by MattMatt on July 29, 2014 at 11:50 PM

          Yes. If you are ever in doubt if oil is fully decarboxylated you can heat it to 110c and see if there is activity on the surface. If there is not then the oil is done, if there is then keep cooking until activity stops. Some people stop cooking just before all activity stops to avoid degrading any THC to CBN. But such degradation is minimal if you stop cooking as soon as activity stops and is better to have fully decarboxylated oil with a little CBN than half cooked oil with more THCA than THC


  4. […] carboxylic acid (THCA), which becomes THC when exposed to heat or UV light. Because of this decarboxylation process, most of the THC you experience when smoking cannabis is actually THCA in the flower […]


  5. […] always remember that eating decarboxylated marijuana produces a far stronger effect than smoking the same amount of raw plant material, […]


  6. […] always remember that eating decarboxylated marijuana produces a far stronger effect than smoking the same amount of raw plant material, […]


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