By Troy Ivan
ibc@ichibancrafter.com
QUICK WASH ETHANOL (QWET) EXTRACTION
A clean and safe cannabis extraction process that can be performed at home is called “Quick Wash Ethanol,” shortened to QWET. It involves freezing cannabis and ethanol before combining them to soak the cannabis and “wash”(a verb) the cannabinoids and terpenes from the plant material. Once the combination of ethanol and cannabis has soaked, it is strained to separate the plant matter from the resulting ethanol solution, also called the “wash” (a noun). The wash contains all the components harvested from the cannabis and will later make up the final concentrate once the ethanol has been removed by forced evaporation. The best wash technique will create a concentrate with the maximum amount of cannabinoids and terpenes but the minimum amount of undesirable components like wax, lipids, and chlorophyll.
First, I wrote a blog post, “Super-Cooled QWET Wash for Cannabis Extraction Using Dry Ice,” explaining the process when I first experimented with very low temps with good success. As soon as that post was finished, I wanted to revisit the dry ice exercise to find out how far the wash process could be pushed and how it compared to simply using the freezer. So, here we are with the follow-up post and the epic Battle of the Wash: Dry Ice vs. Freezer!
WHY FREEZE?
There are many methods of infusion and extraction, all with distinct advantages and disadvantages. QWET, using high-proof food-grade ethanol (95%) as a solvent, has the advantage of high efficiency in collecting cannabinoids and terpenes. Unfortunately, that high efficiency of collection also extends to aggressively collecting undesirable water-based components like fats, lipids, and chlorophyll, ethanol’s only disadvantage. Fats, lipids, and chlorophyll can be acceptable when making oil for edibles or Full Extract Cannabis Oil (FECO) but undesirable for high-quality concentrates intended for smoking. To craft a concentrate free from undesirable components, they must be neutralized with freezing temperatures during the wash. When the plant material is frozen, and the ethanol temperature is below freezing, the polar attraction of the ethanol and undesirables in the plant matter cannot latch onto each other. The undesirables then stay with the plant matter when it’s strained away, leaving only terpenes and cannabinoids in the wash. The well-filtered wash should be a light golden color with no green.
MATERIAL?
I planned to use high-quality indoor dried buds for this battle to achieve high yields. Unfortunately, the material I got was crusty and not great quality. Using lower-quality buds may have actually been a blessing in disguise. I set the bar low for expected yields in using lower-quality buds, knowing high-quality dank will surpass it.
The goal in preparing the buds was to break them up by hand as much as possible, with the least amount of damage possible, to allow ethanol to flow freely over all surfaces. Ripping, tearing, cutting, and trimming plant material causes cell wall damage and will enable undesirables to flow unimpeded into the wash, contaminating and turning it green.
PROCESS
Pitting dry ice against the freezer required numerous runs of different durations to collect enough data points for meaningful comparison. I decided to do 3 runs in the freezer and 3 on dry ice. The washes would be 5, 10, and 15 minutes long for the freezer compared to 15, 20, and 30 minutes on dry ice. Each run used ½ oz of cannabis. After breaking up the buds and removing stems and seeds, there were 6 samples containing 13 g each. 3 bags went into the freezer for 24 hours, and the other 3 into a cooler with dry ice for 2 hours. The ethanol was also portioned between the freezer for 24 hours and the cooler with dry ice until it reached -40° F.
Once the materials were adequately cooled and frozen, it was time to make the wash. For each bag of frozen cannabis, enough chilled ethanol was poured to allow unrestricted movement of the material in the solution. Then, the bags were retired to the freezer or the dry ice cooler to soak for the predetermined period. The 5-minute washes were lightly agitated every 1 minute, and the longer washes every few minutes. When the time was up, the plant material was quickly strained away using 2 wire mesh coffee filters and then more finely filtered using a Buchner funnel. Once crystal clear, the samples went into a mason jar.
The concentrate was created at low temps under vacuum, around 100° F, and the ethanol was recovered for reuse with my DIY vacuum still system. The oil was lined up on silicone mats in order of extraction duration and grouped together with the freezer and dry ice samples separated. Finally, the oil was placed in a vacuum oven for post-process purging to make the final product into shatter and ready for comparison.
FREEZER OUTCOMES
My expectation for the freezer washes was that as the soak time lengthened, I would see more and more green, with the 5-minute wash looking good and the 15-minute wash looking glaringly green. I was shocked and pleased to see the 15-minute wash come out nearly the same color as the 5-minute wash. There was only a slight difference between the 5 and 15-min while virtually no difference between the 10 and 15-min wash.
Once the final product was finished purging in the vacuum oven, it was apparent that the color of the shortest wash was only slightly lighter than the longest, but not by much. The final products were relatively consistent in color for all three samples, with the shortest wash showing only a marginal advantage with lighter color. The yields of the three washes from shortest to longest were 12.5%, 15%, and 15%.
DRY ICE OUTCOMES
The shortest dry ice wash was 15-min, so I could directly compare a freezer and dry ice run of the same duration, followed by the 20 and 30-min washes. Again, by the time I got to the 30-minute wash, I was expecting to see obvious signs of green in the wash, but again, I was happily surprised to see almost no difference in color between the shortest and longest soaks.
All three final purged products came out very similar, with the shortest soak again showing only a marginal advantage in quality while the 30-minute soak still looked terrific. The yields from shortest to longest were 11.5%, 14%, 15.5%
Emboldened by the beauty of the 30-minute wash success, I was determined to find the limit and see where the undesirables would finally make their way into my wash and contaminate it with the green leak. I decided to perform a 1-hour dry ice wash in the same manner as the others. Again, a beautiful wash resulted, and the final product looked nearly identical to the 30-minute wash and yielded 16%. I was shocked again.
CONCLUSIONS AND CONSIDERATIONS
The shorter washes in each group were clearer than the longer ones, which is commonly expected. The unexpected was the narrow margin of clarity and color quality of the finished concentrates between each group’s shortest and longest washes.
I believe three factors made the very clean, long washes possible. First, while broken up thoroughly by hand, the material suffered only minor cell wall disruption, keeping the undesirables well contained. Second, through the entire wash cycle of each run, everything was kept well chilled and not allowed the chance to warm or vary in temperature. Third, the alcohol and plant material was separated with great expediency and never squeezed nor pressed.
In general, the yields of both groups increased with longer soak times, as expected. The 10 and 15-minute washes from the freezer were identical, both 1.96 grams. I think the 15-minute wash would have been a bit more if I had been more disciplined and consistent with the amount of alcohol used with every wash. It is apparent in the photos that the 15-minute freezer wash was 2 fl oz short of the other samples. I believe this reduced the final yield of that wash to some extent, but I don’t know how much. The dry ice samples showed an increase in yield to the 1-hour mark but increased at a slower rate between the 30-minute and 1-hour washes. I’m convinced the yields in this experiment were low due to the quality of bud used and can be improved with higher quality buds.
The stark difference between the freezer and dry ice runs clearly demonstrated that the lower temperature of the dry ice QWET immobilizes undesirables and increases color quality. I think using the dry ice performs two processes at the same time. Typically, QWET is done in the freezer, and then, to clean up further, the wash can be put back in the freezer to winterize. Using dry ice temperatures appears to perform both of these tasks simultaneously.
I would encourage those who try the freezer and the dry ice temps and times to use small quantities and explore which method and soak time suits their preferences best. This craft has no right or wrong; it only makes you happy, and your friends pass out. Whatever you choose, crafting with cold QWET will help you make FIRE with ease and win bragging rights!
IMPORTANT NOTE: I used ExtractCraft mats in this post but I do not recommend their equipment.
STAY LIFTED MY FRIENDS !!!
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