Originally Posted by Gray Wolf
I would try at -50C. The polarity of ethanol also drops with temperature, so its not as prone to pick chlorophy, and tolerates long soaks.
Today I tried two small tests and got around 19% on bud that is in the low 20% for THC-a. I started by staging the bud and ethanol in the -86 C freezer and transferred to the -30 C freezer for the soak, agitating every 10 minutes.
After an hour and a half, the solution looked light yellow but not quite saturated so I tried the -18 C freezer. Maybe 20 minutes later I found the yellow got more intense, almost gold. I started to noticed some green and stopped.
I checked the trichomes after air drying the bud by laying on a paper towel. Some loss of API can be assumed. I washed the bud until most of the stalks appeared furry and minimal trichome heads could be observed.
I anticipate that the remaining trichome heads could be extracted at the expense of some added green pigment to the solution.
Bud was broken apart by hand to sizes not greater than a nickel.
Test 1: 2.6 grams of bud, 19.25% yield
Test 2: 1.6 grams of bud, 17.86% yield
I took a small test bud, along with some ethanol, and put a 50 ml test tube and placed in the -86 C. Even after 4 hours I didn't see green pigment in the solution.