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.

702 responses to this post.

  1. Posted by Dustin Solano on February 27, 2017 at 8:33 AM

    I’m wanting to make a THC-A tincture using BHO. Do I still need to decarb my concentrates before infusing with oil?


  2. Posted by Trev on February 23, 2017 at 11:11 AM

    Hey I’m decarbing some raw hash oil it’s been in the oven for about a hour now and there is no sign of bubbling what you thing is the problem.


  3. Posted by amber on February 16, 2017 at 12:10 PM

    Can I decarboxylate raw hash oil in a conventional oven? if so, what temp an for how long? Also, does decarbing raw oil release dangerous fumes i should be careful of?


    • You can decarboxylate in a conventional oven using the approximate time show on the chart, and can tell where you’re at, by watching the bubbles.

      The CO2 and H2O bubbles released are non toxic and non flammable.



  4. Posted by Tea Pea on February 7, 2017 at 8:04 AM

    Just wondering why you chose to go with 250 instead of 290?
    Is it because it’s easier to gauge when the CO2 bubbles slow down… due to the length of time (7 vs 27 min) and thus easier not to over do it?


  5. Posted by lisa ableitner on January 26, 2017 at 6:00 PM

    How long long do u leave it steep in 250degree oil which is in another container (double boiler)


    • Depends on what level of decarboxylation I am shooting for, but I tell by watching the CO2 bubbles produced to tell exactly where I am in the process. Generally at 250F, it takes in the neighborhood of 30 minutes to hit 70%, which is where I usually stop.

      Check the graph demonstrating rates at different temperatures.



  6. Posted by Maia Hughes on January 25, 2017 at 9:20 AM

    How do you set up a hot oil bath. I have 2 grams of wax that I need to decarb for edibles, I will be wanting to make it into coconut oil. This is my first time and really don’t want to mess it up.
    Thank you!


    • I found a good quality fondue pot to be a good way to make and maintain an oil pot. They are typically accurate at the ranges we operate in, where hot oil cookers like the Fry Daddy are really meant to operate closer to 375F.

      We used a Quissanart, but have also used a Revel, and just fill them with canola oil and heat them to 250F. Set a bain marie or other stainless container of oil in the bath to heat. Be careful and make sure it can’t turn over if it floats in the bath.



  7. Posted by Ja gab on December 31, 2016 at 6:53 AM

    Aloha Bro
    When making cannabis oil from Rozen what is the mixture or milligrams of marijuana to Vg for vapor pen oil,,


  8. Posted by Darby on December 23, 2016 at 9:01 AM

    Don’t put it directly into the oil bath unless you want a very weak oil tincture, it will dissolve into the oil and you will not get it out. Place it in another container and that sits in the oil bath, you are making a double boiler.


  9. Posted by Lloyd E Songer on December 22, 2016 at 2:41 AM

    Hi. My question is this when doing a BHO. After purging in the vacuum oven. Can you decarboxylate before you do your dewax to put it through a short path distillation unit with a cold trap to capture the ethanol?


  10. Posted by Blue kangaroo on December 19, 2016 at 8:48 PM

    CBDA to CBD Decarboxylation is slightly different. From what I understand, it happens at 266 F (176 – 275) for 60 minutes


    • Posted by lisa ableitner on January 26, 2017 at 6:01 PM

      Oops – I found th answer😬 Thank you. Any other tips will be greatly appreciated. Thank you again


  11. I had no idea that butane honey oil extraction is the most clean method of extraction of cannabis. It is interesting that butane extraction is so effective because of it’s nonexistent level of polarity. Many people may be attracted to butane honey oil extraction because of the potential health benefits available with the use of natural and essential oils.


  12. Posted by WAXMAN on December 13, 2016 at 11:22 PM

    CAN I decarb. wax alone without any other additions ie: coconut oil?


  13. Posted by James kelly O"Reilly on December 13, 2016 at 11:01 PM

    when measuring decarbed BHO ( with the 1 to 1 coconut oil ) BHO is 78% without coconut .what is the recipe for 100 mg per gummy. How much 1 to 1 BHO do I put in? thanks.


    • 100 mg/.78 = 128 mg required per 100mg dose.

      Weight of gummy bear minus 128 mg equivalent concentrate dose = candy weight in recipe



      • Posted by Nick on December 15, 2016 at 3:30 PM

        GW- He says it is 1:1 with coconut oil. So, the 1:1 is the formula becomes 100/(.78/2) = 256 mg for a 100 mg dose.

        Although that seems like a rather strong dose for a gummy bear. It is so difficult to just eat one. 😉


        • Posted by Al Khemi on December 15, 2016 at 6:44 PM

          Man, this is like “Lifestyles of the Stoned and Secretive”…personally, it sounds like y’all live in the growers’ laps – can’t imagine what would be possible with access like that..SALUT, y’all – that’s one hell of a gig!


        • My bad, I was looking it as a 78% THC concentrate. If it is 50/50 with coconut oil, it would have to be doubled.

          I’ve never made gummy bears, but I have lollypops, and didn’t need any coconut oil.

          100 mg is about one full dose for an average person, and it is hard to eat just one gummy bear, versus a hand full. Carla’s Truffles consistently OD folks who couldn’t settle for just one, so we stopped making medibles.

          In WA they limit one dose to 10 mg THC, and up to 10 doses per package………………


          • Posted by Living for now on February 21, 2017 at 11:12 PM

            Ya the 10mg is bullshit… I do 1.5 grams of 92 and up shatter… yes it’s under 10 a gram but ya grow up with friends they grow since kids and u develop an autoimmune disease that attacks ur brain and spin ya they treat ya for almost free in Idaho but I am the first 4oad into Idaho on the wa and Id border…

  14. […] You can always use an instant-read digital cooking thermometer for more exact measurements. This article shows the time/temperature curve for decarbing cannabis and offers some other useful thoughts on the […]


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