Acetone crystallization of THC-A


I was vocal in meetings with regulators that it was a stupid** move.

When residual solvent testing was first implemented, there was a limit. 5000ppm. (rumor has it that) all the CO2 guys failed their first try. then bitched so hard that the limit was removed. based on the federal guideline that any amount was ok, so long as it is called out. they actually removed ALL alcohols from testing for a month or four. then restored MeOH, IsoP-OH and Butanol, but left EtOH off the list. I suggested 500ppm for inhalables based on the data you (almost) cite.

these are the same clowns that defined CO2 as a hydrocarbon.

this 2016 document lists 5000ppm.
this 2017 document lists no limit.

many labs still test for it. 500ppm is easily achievable, and my go to target.

They also managed to tangle up tinctures for 6-8 months if I recall correctly. they were permitted, and defined as “alcohol, cannabionoids, and maybe other ingredients”, but the rules clearly stated they needed to test below 5000ppm EtOH in order to be sold. unclear on the concept…

** I have proposed fixes for stupid on more than one occasion, but I’m no longer convinced that infectious gene-drive style IQ gains would actually solve the problem.


Ooof, hard to argue with people so sure of their ignorance.

Crazy to hear they were having so much trouble clearing 5000. Deeper vac!


1000 ppm for ethanol is completely reasonable. Anyone properly drying their extracts can clear this. 500 ppm…that could get tough, but do-able. If you are above 5000 ppm, go home and try again.


What’s the limit for live resin Sauce in y’all’s states…

That’s question for everyone that applies to


What do you mean by limit? Purchase limit?

Or solvent ppm?


Here’s Colorado residual solvent limits.


The residual solvent limit is solvent dependent not product dependent.
Although some states (legitimately) have stricter limits if you’re huffing it rather than eating it or rubbing on your skin.

5000ppm for “Butanes” and “Propane” in OR.
Link already provided…


Omg… OR is pretty lax with the residuals.


Was talking about solvent in it so you can smoke


Ah, yeh check the link.


(Amount of crystals in each dram does NOT show loss) Far left is from my first batch of crystals. i took a small amount and recrystallized them, which is in the middle dram, and the last one is after a pentane wash.
Thank you everyone for your valuable information.






These little ones have been forming for quite some time now. I disolved about 7g of lowerend hash oil into 70g of acetone, thinking the proper ratio was similar to ethanol, and winterized. After vacuum filtering the frozen solution in a chilled filter and removing the acetone to the point of creating a sludgey solutio I capped and allowed to sit at room temp. After burping for a few days to get to regulate the amount of solvent left in solution the crystals started to form. After 2 weeks of being left at room temp the solution stalled and burping didnt make a difference for a solid week so the jar was thrown into a 90° oven for a week and the development started bacj up without the need to burp the jar. Burping the jar seems to help the reaction a bit but it isn’t doing much as of now. I’m doing a larger batch with hplc grade acetone once I get the right reaction speed and will try again with a different batch of oil as I’m curious as to how much of the THC activated while the oil was sitting after being made. Any input is greatly appreciated!


I have successfully growing all of my crystals in acetone. I don’t cap the jar. I place mesh over the jar and tighten it down with the cap ring that comes with the jar. I store this in a cabinet. The ambient temperature varies between 60-90 degrees depending on the day but I have not seen a difference in my crystal growth due to temperature fluctuations.


I’d be willing to send your sample/s out for testing.


Ok how much is residual solvent test, do you have any idea? I’m not really concerned on thc amounts, bc it’s sugar sauce I know it’s gotta be high, and I dewax as much as possible…

I almost feel like someone could follow the recipe SOP and I pay for the test, wouldn’t it give the same idea, bc the sugar size is consistent every time… But I’ll do which ever way easiest for you


For the people washing with acetone; what are you using to wash the flower and do the initial recovery of solvent + cannabinoids? I heard “Pandas” aren’t safe to use with acetone as the paint flakes off. So is everyone using centrifuges?