What would be the saturation point when running -45c ethanol on multiple A runs? Can you save solvent buy re using the same -45c ethanol for multiple runs and how many?
saturation point refers to a specific solute and solvent. you have one solvent but many many solutes. to actually figure this out is probably not that simple. to get a “good enough idea” isnt so hard though. nothing beats repetition 
Your most major factor here is definitely going to be the moisture content of your flower. the ethanol will pull water and terpenes. higher moisture = quicker denaturing of your solvent
There are tricks you can do to reproof your ethanol - but you should analyze the cost of reproofing vs just buying more.
based on my experience in this field, assuming average flower you could probably use it a few times, unless your flower is very wet.
final thought… buy a hydrometer. theyre cheap and you can assign proof to your solvent, and track its ability to desolve your product. make a graph, and pick the spot where you see its most cost effective (while maintaining quality of course) to switch. (as denatures itll do a worse job. maybe reproof/get fresh at around 190/195 proof?)
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Yes but depends of % of biomass
And unwanteds
Flower nicely broken will saturate fast but with high cannabinoid content
Flower hammermilled will saturate fast but with many unwanteds
Etc etc
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This man knows that of which he speaks!
I’ve actually processed hammer-milled material in front of the farmer to explain why I have no interest in processing his material. His Buddy was getting pretty huffy when I said it wasn’t coming in the door. Even after he admitted that several other folks had turned it away before me.
if we gave you that saturation number in mg/thc per ml in -40 solvent, or the curve over a range of temps, would you have anyway of knowing where you actually were?
having In House analytics so you can figure things like this out is invaluable.
you could play simple mass balance games using third party analytics.
if you’ve not read the bucket tek thread, you should
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One advantage to drying and decarbing biomass before it enters EtOH extraction is that water is a non-issue and the EtOH picks up very little water.
In a recent run of my mini extractor, I reused the EtOH three times and ended up with 93 proof ethanol after rotovap.
Mini Extractor for Personal Use
At this level, EtOH is easily re-proofed with type 4A molecular sieve beads and is ready to go again after filtration.
Nobody has much data on the solubility of cannabinoids in EtOH azeotrope at low temperatures but I think it is at least 50 mg/cc at -20 where I run.
That means that I should be able to dissolve 50 grams in a liter and this is consistent with what I see using my extractor, even the first of three aliquots of EtOH is not saturated after three passes.
The third aliquot on the third batch still looks pretty clear.
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I’ve used my etoh at the very least 4x over. I always proof it with a gauge after it comes out of the rotovap. It’s always sitting nicely between 190-197ish proof.
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