Ethanol Shatter Purge


Hello All,
I am have made some nice looking ETOH shatter. However , when I tested for Residual Solvent ( ethanol ) I am still at 9,000-10,000 ppm. Does anyone have any information that will help me get the rest of it out? I need it below 5,000 ppm. I am re-starting my purge again but do not want to pull all my terps off … Any input is appreciated . My initial purge was at full vac with the valve open with no heat. I then " flattened" the slabs by light temp ( 75 F) and full vac with valve closed and flipped every 1-2 hours. I increase by 4-5 F every flip NTE 100F.
Thank you in advance.


With ethanol you need more heat to remove the residual solvent since the boiling point is much higher than that of hydrocarbons. When using more heat, be careful, keep an eye on it. trying going up to 115 or 120 for a couple hours on each side. when initially raising the temperature make sure you leave enough time for your extract to reach the same temperature as the inside of the oven before turning on the vacuum.


You may find that it’s easier to remove the ethanol on a hotplate with a sitirrer (and temperature proble). It’s very easy for the ethanol to simply stay trapped in the slab.

I am not sure the wisdom of posting links, but when I google “purge ethanol” and article called “ How to Purge Ethanol from Cannabis Oil Using the CAT MCS78 Hotplate Stirrer” is my first link and it explains the method well. I am not endorsing their product however as I’ve never seen it and I think a lot of hotplates suck.


I’ve been super duper wanting to experiment with an ultrasonic probe in my mix. Get it up to 40c and put the probe in under vacuum and see what comes off.

If I get a small windfall I might give it a go.

Second thought I had was just regular sound vibrations (maybe a subwoofer?)

Other option might be running it over a heated funnel with an ethanol sized sieve, might be exclusionary enough to keep the turps and break that azeotrope.


I’m developing a purge chamber with a homade magnetic stir built under I’ll keep everyone posted


you will need to make thinner slabs to purge out etoh in an oven. you can stick/remelt them carefully after you’re more fully purged if you like.


I am now purging the slabs with full vac at 90F for 12 hours and cycling with no heat with full vac for 12 hours. I will flatten the slab again, once I confirm they are fully purged. I will post my results as I progress. Hopefully the 90F is enough to get the residual etoh out of the slabs and spare some terps. If not, I will have to bump it up. Thank you all for the input.


85-90 is what I’ve always used to purge etoh slabs


Did you cycle heat on/off or just leave the heat and vacuum on until you are below action levels?


From what I’ve been taught, the proper way to purge is to leave the vac pulling 24/7, not off and on.

I always leave heat on as well


Thank you. I am pulling vac 24/7 cycling heat. I may adjust based on your recommendation and leave the heat on.


When I did ethanol shatter I would strive for my slab to be about credit card thickness. I would always do in a vacuum oven - that minimizes oxidation due to lack of oxygen. My vacuum would only get down to 2 inches of mercury, but consistently 2 inches Hg. I would run the vacuum for the entire purge time 24-48 hours but usually 48 hrs. I would have the oven heated the entire time to 105 F. Would have good flavor and product was highly stable glass.

Also worth nothing - ethanol has two carbons and a hydroxyl (-OH) functional group. The hydroxyl group can form hydrogen bonds with neighboring polar compounds, which are require more energy to overcome than the London dispersion forces which account for the attraction between non polar compounds. It should be expected ethanol will require more energy (heat) to purge from a slab when compared to butane.


Didn’t happen to get any ppm readings on the way did you?


Unfortunately no. All I can say it was glass, highly stable, tasty, but sadly no residual solvent testing. No weird sizzling or bubbling either.


I obtained my results … my etoh is below 2,000 ppm which is within spec. One of my slabs seems to be buddering up on me . I am not sure what caused this . It actually smells better than the glassier slab .


thats your terp heavy pour fraction - the terps you smell leaving causes a fairly rapid solubility change and cause the nucleation.


Can I do anything to reverse or stop the physical change?


Was it agitated in any way? Do you think it may have water in it?

Post a pic if you can


I have 5 slabs stored in the same oven ( off and sealed). The top slab is the one that is buddering up and it smells really good ( super terpy). Do you think the terps coming off all the slabs combined are rising to the top of the oven and being absorbed into the top slab near the interior ceiling of the oven?


What about a diaphragm vacuum pump on a HeatVac vacuum chamber @125F. Will a continuous vacuum help?