I bought a Coldfinger to make an extract, but my problem is this: Doesn’t marijuana have to be heated to become psychoactive?
My solution was to put the marijuana in the oven before putting it in the Coldfinger. But I have no idea how long I should leave it in there, let alone at what temperature. I know THC boils at 392 degrees F. But other cannabinoids, which are essential to the experience, boil off much more quickly. At what temperature can I decarboxylate the THC, while still preserving some of the cannabinoids?


Marijuana produces THCA, an acid with the carboxylic group (COOH) attached. In its acid form, THC is not very active. It is only when the carboxyl group is removed that THC becomes psychoactive. When marijuana is smoked, the THC behind the hot spot is vaporized as the hot air from the burn is drawn through the joint or pipe bowl to the unburned material. The liquid THC and other cannabinoids have a boiling point of between 180-200? C (355-392? F). Before they turn gaseous, at around 106? C (220? F), the carboxyl group is released from the molecule as carbon dioxide and water vapor.

You will be extracting the THC using low heat in the commercially made Coldfinger Extractor. (They have a very interesting online catalog at The THC will not reach a temperature in which decarboxylation takes place. However, if you plan to vaporize or smoke the extract decarboxylation will take place as the oil is used.

However, it is easy to make sure all the THC is decarboxylated and is at full strength before it is extracted. Although decarboxylation takes place rapidly at 106? C, it proceeds at a more gradual pace by placing the cannabis in a room with low relative humidity and room temperature. As the temperature rises, the rate of decarboxylation increases.

Cannabis can also be placed in a food dehydrator to remove the carboxyl group. Although the heat in the food dehydrator doesn’t rise to 106? C, the temperature is warm enough to promote drying and the release of the water and CO2. When the marijuana is crispy and brittle you can be assured that the carboxyl group has been removed from the cannabinoids and they are ready for extraction or removal from the plant material.

Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA
You can also email Ed at [email protected], and send queries via his website at
All featured questions will be rewarded with a copy of Ed’s Marijuana Question? Ask Ed.. Sorry, Ed cannot send personal replies to your questions.



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  12. Anonymous on

    I manufacture cannabis-medicated drinks for the collectives…my method of decarboxylation is performed in a dehydrator which does NOT have a fan. Ed is absolutely correct…it does not reach the 106 temp; however, he also mentioned that temperature is where RAPID decarb’ing happens. You want a “low and slow” method in the dehydrator for absolutely BEST results.
    From that point, it is EASY to pull a nice alcohol or glycerin extraction of the product which has already converted into active THC. If you do this properly, the product will be ready to consume WITHOUT the need for further heat or specialized heat extractions.


  13. Anonymous on

    …eat some and tell us, dammit! I’m curious to know as well…but not in a position to find out anytime soon.

  14. Anonymous on

    So my understanding of the last paragraph is that after leaving the cannabis in a food dehydrator the cannabinoids will then be activated. Does that mean that from there, the cannabis no longer needs to be cooked to be in order to feel the effects of it when being consumed?