Excerpted from Cannabis Concepts:

A Guide to Making and Using Cannabis Oil at Home


After harvest, cannabinoids continue to change during decomposition. Chemically, the acid cannabinoids lose a “carboxyl” group (COOH) and release carbon dioxide. This process is also known as decarboxylation.  


All things in nature lose molecules as they decompose. In food, this prepares it to be more easily digested by the body.  For example, milk is fermented into yogurt or kefir, cabbage into sauerkraut or kimchi, meat into sausage, flour into sourdough.  


The same concept is true for cannabis.  A product that has been cured, or decarbed is typically more easily digested, or used, by the body. 


The best example of how decarboxylation affects the body is THCA changing to THC.  Raw (freshly harvested) cannabis has mostly THCA and very little THC. THCA is non-psychoactive.  However, when decarbed, it turns into THC, the common psychoactive. See photo p.16.


When smoking, decarboxylation occurs when lighting the material on fire.  When making oils, the material needs to be heated in another way, or cured over time.


Curing allows the cannabis to naturally decarboxylate over time.  In the same way vegetables are fermented, connoisseurs cure flower in a mason jar, “burping” it occasionally to release the carbon dioxide that is created as it decarbs.   After 3-6 months, it will have converted around 50% of its acid cannabinoids. The flower remains moist so it is not harsh when smoking. However, when making oil, the condition of the flower is not as important. A dry flower is still useful for making oil.  Some people are using raw (acid only) oils, attempting to stop the curing process. In my personal experience, many of the THCA continue the curing process into THC. (CBDA stays an acid longer because it has a higher decarb temp point).


Terpenes are heat sensitive and will vaporize in high heat.  If keeping terpenes and acid cannabinoids is important, use curing, cool extraction, and cool evaporation to make cannabis oil. This method is preferred by many herbalists and natural medicine makers. 


***Too high will burn off cannabinoids, too low will not convert.  250F/120C is a MAXIMUM. Cannabis is forgiving in heat compared to other herbs.  Decarb begins around 170F/65C but for a full decarb in a shorter time the temperature needs to be in this range.


Temp in F          Temp in C           Minutes

250                        120                        25

240                         115                        35

230                         110                        45

220                         104                       55

210                           99                        65