I bet you were hoping for a quick little recipe that would somehow make your plants ooze sticky THC from every pore. This is not that article, but it is interesting stuff and I promise you will learn something new. A few days ago I posted an article on cannabis lab testing in which I mentioned that the cannabinoid levels in lab test results could be substantially inaccurate because of the moisture content of the sample. By over drying a small sample of cannabis, dispensaries or growers could actually game the system and drive up the THC levels in the test results. Unethical, yes, but it’s easy to do. Numerous emails have suggested I explain this in a bit more detail.
The drier the sample, the higher it will test for THC and other cannabinoids. Labs test for the level of cannabinoids found in a given sample of bud. My understanding is that the sample size is usually 1 gram. A freshly harvested gram is going to contain much more water than a 1 gram bud that is very dry. Water does not contain cannabinoids so the higher the moisture content of the test sample, the lower the THC or other cannabinoids in the test results.
This is a bit tricky to explain, but think about it this way. With a wet sample say 50% water the lab essentially be testing ½ gram of bud and ½ gram of water. The dry sample contains much less water, therefore more of the gram is bud and bud is filled with cannabinoids. This is the same reason that extracts test so highly for THC. Not only has the water been removed, but also most of the plant material that doesn’t contain the cannabinoids. This leaves you a sample of mostly trichomes or their oils like is found in bubble hash or kief or hash oil. It’s pretty obvious that you’re one gram sample of hash is going to test at higher levels of cannabinoids than bud. The same is true of dry bud versus wet bud.
Luckily you can use simple math to adjust for the moisture content and figure out the true levels of cannabinoids in your sample. This of course assumes that you know the moisture content of the sample that was tested. Most labs test for this but not all dispensaries show it to their customers. It should be noted that just because the sample that was sent for testing was very dry or very wet, doesn’t mean that the medicine you are purchasing has the same moisture content.
You might think I’m nitpicking over such a small inaccuracy, and for some purposes you might be right. We are not talking about a big difference when we deal with samples ranging from 8-12% moisture content like is found in most dried and cured cannabis. On the other hand, If we are going to spend time to look cannabinoid levels, don’t we want to compare apples to apples. If we have results from two buds with different moisture contents, they can’t be compared until you have adjusted the lab results to a baseline moisture content. If you are testing for breeding purposes or experimenting with growing techniques, adjusting for the water content is essential for identifying slight variations in cannabinoid levels.
First we need to pick the baseline moisture content. Since the average water content of cured bud is about 10%, I am going to use this as the baseline for the calculation. You could just as easily use any number as long as you are consistent.
As an example we are going to look at two different make-believe buds. Both have been lab tested and show a total THC level of 18%. The difference is that one sample has a moisture content is 15% while the other has only 5%.
The difference between the 15% moisture content and the baseline of 10% is a difference of 5%
Multiply 5% (.05) by the THC content of 18% or (.18) which equals 9% or (.009)
Since we know that a water content over baseline will mean more cannabinoids, we add this to the original THC content of 18%.
Our THC content adjusted for water content is .9% + 18% = 18.9%
Now this doesn’t seem like a huge number but let’s compare it to the sample with a moisture content of only 5%. Instead of adding .9% we need to subtract it from the original 18% THC
Our THC content adjusted for water content is -.9% + 18% = 17.1%.
Even though these two buds both showed 18% THC in the lab results, we know that if they were both dried to the 10% moisture level baseline, one would test at 17.1% THC and the other at 18.9% THC. This increase from 17.1% to 18.9% THC is an increase of a little over 10%. When growers are experimenting with methods for increasing the THC content of the buds they grow, a 10% increase is pretty substantial.
There you have it. You’ll never look at cannabinoids profiles the same again.
How to Increase THC with Simple Math,