Testing for Truth Part 3: Does Sun Damage Cannabis?

By Dylan Wilks, CTO

Most of us take for granted that exposing cured cannabis to sunlight isn’t a great idea. Sunlight contains UV light, which has well known destructive properties.  Anecdotal reports suggest that the acidic form of THC, THCA, would degrade into Δ9THC (the active form) and then further into CBN. That sounds reasonable, considering that’s typically how cannabis degradation is explained. Rather than accept the anecdotal evidence, we decided to put some cannabis products to the test. 

Here at Orange Photonics we like to combine space technology with marijuana (remember our line “Mars Technology for Marijuana”?), so why not blast some cannabis with simulated sunlight for a few days and see what happens? I worked on a variety of satellite calibration projects over the years which means developing a NASA grade solar simulator was right up my ally. 

 Solar Simulator

Solar Simulator

The Setup
The solar simulator used for this test is called an integrating sphere. It is a ball, one foot in diameter, with a four inch opening on one end. The inside is coated with a special material that is one of the whitest and most reflective materials known to science. Light sources are positioned so their light is directed into the sphere from smaller holes so that the light bounces around the white inside and provides an even (and very bright) illumination at the main opening. The light sources are chosen to match sunlight as close as is feasible. I calculated the output of our simulator to be approximately the same light intensity (irradiance if you want to be technical) as a sunny day in Florida during the peak of summer.  In other words, pretty bright.  

Usually a satellite camera is placed at the opening to calibrate the camera sensor before launch. In this case, I placed 3 cannabis samples at the opening: Two flower samples and one ethanol extracted shatter. After preparing the samples, the solar simulator was fired up with the cannabis samples in place. We decided 40 hours would be a reasonable stop point reasonable amount of time to irradiate the samples

 Samples with a suntan!

Samples with a suntan!

Much to my family’s relief, I didn’t cause any fires while running a high-powered light source in the basement for 40 hours straight. So far the test was a success...

The samples pre and post irradiation were analyzed on an Orange Photonics LightLab analyzer. What we found was not what we expected, though the sunlight did damage the samples. There was loss of cannabinoids in the sample across the board for both flower samples. We found no decarboxylation of THCA into Δ9THC, and no discernible CBN created. The total loss was about 20%. The shatter sample showed no discernible change in cannabinoid levels.  


After we analyzed the data, we found that these results actually make a lot of sense.  The UV light is likely causing degradation of the cannabinoids but wouldn’t cause a chemical reaction like decarboxylation. Instead, a photon of UV light might hit a cannabinoid molecule at any of the chemical bond locations, possibly breaking down the molecule into smaller constituents, many of which will not be stable and will further degrade, leaving no trace of the original molecule. Thus, sunlight will simply cause the overall potency to decline.  We saw about a 0.5% decline with each hour of sunlight exposure.

Why didn’t this happen to the shatter? The pieces of shatter used were round-ish balls by the end of the test, so not much surface area was exposed to light.  It’s dark color and limited surface area probably protected most of the cannabinoids from degradation.  

In summary, the original anecdote about protecting cured cannabis from sun exposure is correct, however you won’t see rising levels of CBN or Δ9THC as we originally suspected.  You’ll just lose potency with sun exposure. There was a lot more detail that went into this study than is presented here, so please let us know if you have suggestions or questions for us, including what else to blast with a solar simulator!