Here is my drawing of the entire process from Cannabis extraction to cannabinoid distillation. It includes solvent recovery using a falling film evaporator, which operates on the same basic principles as a rotary evaporator.
I hope these are “worth a thousand words” insofar as explaining how cold ethanol-based cannabis extraction generally proceeds.
One thing they may not reveal is the purpose of using low temperature (and 5% water) tuning of ethanol’s selectivity as an extraction solvent. The main reason for this is to avoid the necessity for excessive post-extraction clean-up of the liquor. Warm extraction with ethanol can bring a lot of undesirable compounds into the mix, such as sugar, protein, alkaloids, etc.
Another useful fact is that you do not need to worry about the efficacy of the ethanol for multiple extractions; as many as can be done before the alcohol is naturally lost to evaporation, in fact. If there is excessive water in your biomass during extraction, the ethanol may pick up some of it. However, when you recover the ethanol in the rotovap, only use temperatures below about 50°C. When you see the crude resin get milky splotches forming in it, empty the ethanol from the receiving flask and store it for other runs. Then, after resealing the system and pulling vacuum back down, turn up the temperature to 60-70°C to evaporate the milky watery splotches. When the crude goes solid black/brown again and you no longer see drops of condensation forming in the condenser, your crude is perfectly concentrated and ready for the decarboxylation & devolatilization phase of the process!
And fyi, no, you cannot effectively decarboxylate while solvent is still in the crude, because the solvent’s evaporation cools the resin, keeping its temperature at or near the solvent’s boiling point for the given pressure (which is easily below room temperature under vacuum). Once the solvent is finished evaporating, the resin stops “sweating” (i.e. evaporative cooling), so its temperature is free to increase to a degree more effective for decarboxylation (110-120°C).
I’m stunned at how much information is here. It’s like everybody is competing to be most helpful. Awesome, somehow you managed to nail what point in the process I’m at in terms of understanding the system at a glance and getting my feet off the ground. Thanks so much.
If what I was planning on making wasn’t distillate, then what the hell is it actually? EHO? Seems like something smokable safely, just shittier than distillate. I think it would be best for me to look into a SPD rig, but in the meantime, what would I have been making?
I literally saved this first picture to my work computer, it is everything and more that a newbie could ever dream of being useful. As always, very well done.
@tuclibys If you’re only extracting one strain at a time I would commonly refer to what you’re making as Strain Specific Extract. I don’t know what your end goal is here? It seemed like you wanted to throw this into a cart and then sell that? If this is the case then you really need to purge the hell out of your extract in order to get the solvent off. In doing this you’re probably going to destroy your terp profile and I assure you its not going to taste the same as the original terp profile in the plant. Making a cart out of pure SSE is honestly not going to work. The formulation is going to be too thin and will probably leak out of your cart. Also, if the ppm of Ethanol is 5000 ppm (0.5%) in Canada you are not going to want to try and fill carts with just your extract. Just FYI I’m in Florida and our regulations for medical dropped a few months ago and our state requires 5000 ppm of Ethanol for all vape products so this is pretty common as far as low levels go for that solvent. I have posted in here a few times in an effort to stir up ideas on how to remove ethanol and still retain terps but it really is seeming like an impossible mission. You can do some digging around here and probably find the posts I’m referring to. If you want further help or the search bar seems to not be working for you I can try and assist.
Yeah, I’m beginning to accept this. It’s more important to get a decent quality thc yield, and if I’m looking to add terpenes I can still do that afterwards. I like the idea of doing an SSE but if it’s not what I can start doing, I can focus on it later.
Why is that? too thin? If I can’t do an SSE I’m okay with that; if the full terp profile dilutes it too much, I’m okay with using a proportional amount fewer terps as well, but primarily yeah I don’t want any carts to leak.
Thanks so much.
@tetramethylsilane Thank you, noted. I’m okay with EHO as well, as long as it’s quality overall.
@cyclopath When you’re running your EHO/distillate (whichever it is on a given day; I’m not so privy to your processes) in your pens, which I saw from your other thread that you get from R&D, what sort of typical thc% do you end up with (if you know), and how would you rate the flavor compared to distillate?
I’m going to let you know this because once you see some things on a GC you can’t unsee them. The terps you buy that claim to be pure are not at all pure. They have so many peaks that are other terpenes and even solvents sometimes. The major peak on there is the terpene in question but it is surrounded by so many other peaks as well. If you can get away with adding as little as possible I would recommend that. If you could get a wipe film you could just use the distilled terp fraction and the cold trap terps to make your carts hella fire. Add back 8 to 10% SSE and you got yourself a gnarly cart.
@CannabinoidChemist Thanks for the heads-up. I won’t be adding third party terps if I can avoid it; ideally I could just keep them from the green like you’re suggesting. I read the entire thread about the TT debacle and it was enough to scare me off. Question, you said
If you could get a wipe film you could just use the distilled terp fraction
If you need terps, because you cooked yours off on a hot plate, then you have to purchase them
is that suggesting that you don’t necessarily have to cook the terps off when you’re decarbing, but that I would probably end up doing that because of my process choice? or are you just talking about whatever terps made it through the decarb? I’m not sure what terp fraction would remain after the decarb, depending on which step it happens in and how you do it, like how cyclopath was suggesting I could decarb under pressure. That seems like something I would have to test if I got access to a still.
There are still vape pens I have made and smoked with added terps its just not the best honestly. If you want to make a pen that is more true to the plant just use disty, terp fraction, cold trap, and SSE to spike the major terps youre really trying to target. You can decarb in a reactor or reflux with a condenser, my favorite, to retain terps. If you do lose terps its fine the major ones will stick around through distillation. But really im speaking from wipe film. Terps from SPD are terrible? Idk little to no experience with those. But from reading they can be pretty bad. Although maybe someone can weigh in with their knowledge and drop you hints on how to make them not so bad.
CTT off that wipe film often smell a little off as well but when you get the residual ethanol off they smell AMAZING! I love taking a drop putting it on my skin and letting the ethanol evaporate. After that when you smell them its very floral. I have a few vials of CTT from the short path that we had operational for a few weeks and they are in two layers, not sure what that’s about. They smell like straight $#!+ !!! Never in a million years do I think you could clean those up to the point that they would be safe for human consumption via vape. I bet you could clean up those residual terps or distill them in such a way that they come out much cleaner and more desirable to place them in a cart.
What about wipe film? The way you say that is creeping me out bub…
For a little while here we would separate the CTT from our initial terp cut, and the ones from our actual distillation. Those heavy terps from distillation smelled absolutely rank, but I find the initial ones are lighter and don’t smell nearly as bad. Used to love having people come through on a facility tour and getting them to take a big whiff.
Bahahaha its all good I know what you meant it’s Monday and I have energy like its a Friday so I’m just having fun on here.
Do you have a picture of them? Are they amber? Red? Brown? I know that rank smell all too well and the worse it was the higher the percentage of EtOH in my CTT was.
You extract with ethanol? Maybe its your starting material? Was it over 30 days old? Full of mold? Truth be told they could just be old.
