How to get crude up to 80%


pretty sure you’ve only got one theoretical plate in your rotovap. If you’re using a hydrometer/proofing gauge & your liquor is coming back at 190 or better, then clearly it can be done. That doesn’t make it the right tool, and you are removing water until you hit the azeotrope. not avoiding it as you originally posted.

here’s a 25 page white paper @Photon_noir & I put together on the subject of ethanol extraction. feel free to tear that apart in public.

perhaps we could get back to OP’s pre/post processing to get higher numbers?

@sunny 80% THCA is easy via cyroethanol. Now that I’ve gone back and done the math, 80% THC without post processing isn’t all that difficult either.

although calling it crude at that point seems disingenuous.

My best EHO to date (no scrub) was 92% THCA which exceeds your 80% THC threshold by a whisker.

if that doesn’t make sense. read up on why 100% THCA is less than 88%THC


This looks like it is going to be a good read


I like the info about refining that recaptured ethanol. When doing that do you just run it off the vacuum? I was thinking of using a larger flask and setting it up on an off night and letting the etoh slowly work its way through the vigreux column w/o vacuum running. How do you guys do it?


I wonder if 75% CBDa would be achievable with a cold etoh wash of ~10-12% biomass? It would make crystallization (after decarb of course) a hell of a lot easier.


65-70% CDB (decarbed in recovery still) has been my experience washing with cold ethanol.

Centrifuge didn’t change that. just the amount of solvent I get back.


I guess the questions here are how to achieve 190 proof ethanol after excess water has been introduced, and how much cannabinoid can be extracted using ethanol… is that correct?

An azeotrope has a set boiling point. That means, if the water b.p. is sufficiently higher than the b.p. of the azeotrope (it definitely is), then you can distill 190 proof out of the water mixture by careful distillation using whatever method. If you see 195 proof on your hydrometer, you probably need to adjust the reading for temperature; always use a thermometer in tandem with your hydrometer, and check the temperature adjustment chart. It is possible to distill out a higher proof than 190 using column fractionation, adsorbents, drying salts, etc., but it is not likely to happen during a simple rotary evaporation.

As for extraction, the percentage of cannabinoids in your crude is highly dependent on the nature of the resin existing on the plant. If the resin has a lot of light terpenes and terpenols, then those will probably distill out of the crude along with the ethanol during solvent recovery, leaving a higher percentage of cannabinoids in the crude than was originally present in the plant resin. The temperature/residence time (selectivity) of your extraction should be optimized to get the crude cannabinoid percentage as high as possible, too. The more selective your extraction, the less garbage you extract, the higher your cannabinoid percentages will be.


If one removed the volitiles and terpenes prior to extraction with ethanol, would it make extraction easier or harder? Would microwave extracted biomass still be viable for ethanol extractions?


That is an excellent question! My guess is a little harder, since the pre-dissolved cannabinoids in terpenes are much easier for the ethanol to absorb/dilute/dissolve. It is easier for solutes to dissolve when they are already in the same physical state as the solvent, or at least close to it, such as liquid resin going into liquid ethanol… as opposed to solid resin acids (cannabinoids) going into liquid ethanol. It might just take a little longer residence/soaking time for the latter.

I do not know what might happen to the waxy cuticle or other components of the plant matter during such a process. However, barring unforeseen circumstances, such as cell destruction during whatever process one uses to do this, the ethanol should still easily dissolve cannabinoids, especially in their acid forms (extra hydroxyl group). I would try to avoid decarboxylation at all costs, though, since that will reduce the ethanol’s affinity for the cannabinoids… although decarb is actually recommended prior to CO2 extraction, for the same reason (change in molecular polarity).

I assume by “microwave extraction”, you mean gravity and/or steam distillation of essential oils, like terpenes. See above for my thoughts on that.


I see now the OP wants 80+% cannabinoids in crude. Yes, it is absolutely possible. The key is very selective extraction, as described. My first “CLS” butane extract tested at 82%, and that was not Winterized or anything. Running nugs, broken into 1/8" to 1/4" pieces using properly chilled ethanol could easily get you into the upper 80s or low 90s. It may take a little very careful post-extraction processing to get into the 90s, but with the right resin (high cannabinoids and less than 10% essential oil terps), it can be done.


Thank you very much for the very informative reply! I see that CO2 extraction would be superior to ethanol for decarbed, terpene exctracted biomass. This would allow one to skip the subcritical extraction all together! Thank you once more, this site and it’s contributors are the crown jewel of the cannabis community!!!


Supper dry bio mass. 4 quick washes with centrifuge at -17C. (Then B run warm wash put to side) Roto. First pass on A run comes over nicely and crude tested at 75% from 13% bio mass. No post process.


You’re welcome @qma, but I think you may be misconstruing my meaning. CO2 is not superior to ethanol in any way for cannabis extraction, except for subcritical (liquid) terpene extraction. CO2 is quite inferior /especially/ for extracting cannabinoids without terpenes! It is too small and non-polar, so supercritical or liquid CO2 dissolves and carries cannabinoids far more slowly than ethanol. Not only that, but extracting with CO2 is excessively NON-selective, so it grabs a bunch of wax and lipid garbage that one will have to remove by Winterization with ethanol, anyway!

Thank you for the empirical values, @Oreo!