The reason light was blocked was so thefe was no chance of degrading thc or any canaboids,another reason was so the natural maturation process of thc that takes place in the abscence of light would not be lessoned.
Ive since found out that simply running a 60 watt green bulb set up with a thermostat controling the bulb works just as good as covering the bulb to block light,up until about 6 weeks ago i was a co owner of a medical co-op in michigan,ive since sold my interests back to the membership as well as selling my grow op & the building to the club,at the club we regulary sent samples of our most expensive med strains in for analysis of thc levels,i had the max number of patients allowed to a caregiver so my grow blew up pretty large,i ended up needing to use 6 dryers full time so i built additional machines.
A couple of the dryers didnt have covers over the light bulbs,when samples are tested the lab results are only good for one year,after that strains need retested at the lab ,later samples i sent in were from dryers where light was blocked as well as dryers were the buds were dryed under.green light,awhen comparing lab results against results from the previous years results any differences between them was negligable & were so small i concluded that green light did not need to be blocked.
I now have a tiny ass lil grow where i only grow 4 plants in soil under a single 600 watt so i dont need dryers any longer,i now hang dry my smoke using more common methods,i also have buds that were slow dried & have been cured for well over a year that are left over stock that was for the club,of all the different methods used to dry/cure these buds its all the same,good stuff.