Winterization Optimization

Hi everyone!

First off just want to say thank all of you who are posting, I am new to this forum and been quietly watching for about a month, and I have learned an insane amount from you all. I love reading this forum and watching the stigma of the “lazy stupid stoner” being absolutely smashed by the work everyone is doing. So many self taught organic chemist here, and its amazing!

So I am here to ask some questions about our winterization process and get some input on how we are doing and any optimization tips you guys may have.

We are decarbing our material and then placing it into a CO2 SFE system for extraction to get our crude oil. The main process I am inquiring about is the ethanol step and possible ways to lower the allotted time for this process and potentially even find some better steps to take over the process.


  1. collected crude oil from collection vessels and take work station to be weighed
  2. Heat ethanol to 60C.
  3. Mix ethanol with crude oil to achieve a 5:1 ratio of ethanol to crude and place in stirring bar until mixture in homogeneous.
  4. After mixture is homogeneous, add -20C cooled ethanol into mixture to achieve a 10:1 ratio of ethanol to crude.
  5. Place in -20 cooler for 24 hours before filtering and repeat the filter process after another 24 hours of -20C cooling.

After this our crude is seemingly free of most, if not all waxes and lipids. We have been getting decent THC percentages in the mid to low 70’s on the refined crude and are expecting even better on the distillate.

Some questions I have
-According to our methods we are suppose to run a 3rd filtration after a 48 hour -20 cooling but the crude after the 2nd time seems to not need it. Is this a big issue, or is it just affecting our final THC percentages? Everything is going to be turned into distillate so I feel a third is unneeded but I may be wrong.

  • Is the 60C to heat the ethanol before mixing with crude too high? I have seen some people do anywhere in the range of 30-60C but I am unsure of the advantages and disadvantages of the higher or lower temp range.
    -When I add the -20C ethanol to make the 10:1 ratio, it seems to instantly crash out a good amount of waxes and lipids. Would it benefit us to run a filtration after this step or would that still leave the need for at least 2 more filtration after that?

Also willing to take constructive criticism on any steps or tips you may have. Thanks in advance for all the help!

Is your filtration happening in a freezing condition ?
Or yust fast that no waxes get warm enough to liquify ?
What micron is your filter media ?
24 hours seems short at -20 for co2 crude @extec90 is one of the co2 extraction grand masters see if he has any input




From my experience, a third pass is unnecessary. The only way it would really be worthwhile is if you did the third pass at -60 or less. 60C is a good mixing temperature, the only thing I would advise is not dumping frigid ethanol in the mix.

The rapid crashing traps oils in the globs and makes it harder to wash the waxes completely clean. The advantage to having everything hot is the gradual crash, it’s really just making the filtration faster/easier.


Why not do a room temp to take the bulk of gats out then freeze. I room temp filter then do 1 cold filtering and straight ro roto


Awesome, I assumed the third pass was unnecessary since we are already getting good crude test results back.
Would you advise a filter at the beginning before the first freeze? and if no frigid dump, would you advise allowing it to cool to room temp before dumping in the -20C ethanol to make the 10:1 ratio or just using the heated 60C ethanol to make a 10:1 ratio?

This is what I was wanting to do, but just wanted to ensure that it wouldnt cause problems in the process!

I would advise using room temp ethanol to bring it up to 10:1. I wouldn’t bother filtering at room temp unless you’re trying to put a lot of volume through a small filter, it can make the first cold pass easier if you’re stuck using little buchners to filter. Otherwise, it’s just a waste of time and filter paper.


I have always done a room temp to take the bulk of the fats. 30-50gallons usually and then wash the fats with cold solvent to get close to the 10:1 and then into the freezer minimum of 18hrs then through a 1micron stainless filter then its ready for the roto. Otherwyin my experience you have to keep stepping down your cold filtering micron papers and takes days. I can start on monday and its done and in the roto by Tuesday. Just my method and experience

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What freezer do you use to take that volume to freezing in 18 hours ?
Just curious ?

Basic kenmore deep freezer that always has dryice in it to pack around the immersion chillers. Its all in 5 gallon buckets so it doesn’t take long to get cold.

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Aha it might set someone on the. Wrong foot not knowing that only a freezer without some dry ice most lickly doesn t have enough power to get frozen in 18 hours :+1:

You dont have any issues with di in your freezer? I was worried about the di offgassing and blowing the door off.

I was going to alter my wash to have my SS pots rest in the freezer to help keep frozen.

No i dont wven have them plugged in there just giant coolers basically, and there not air tight enough to have the lid blown off. Just dont stick your head down in there, there aint no oxygen below the rim


Worst case to be sure drill a small hole where there are no coolant lines in the freezer and have some plugs to plug it when not in use to off gas
All medical or lab freezers have a hole for temp probe wires

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I was thinking of just shutting it and not locking it. if it’s too much pressure, the door should just pop the seal vs pop the door off.


Yes annd it will
In the door of any freezer there are no cooling lines so thats safe
I have 4 butane cilinders hard lined treu the temp probe hole in the medical freezer some rockwool between gaps
And no problems of ice forming (-86C)

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I had someone tell me that you could do 18 hours in -40 freezer, what are your thoughts on that? :thinking:

See: Winterization

Yep. That works. To an extent. Depending on solvent ratio and initial extraction temps.

Using In House analytics to define the sweet spot for any given extraction operation would be my response.

Depending on scale and initial solvent of choice, there are alternate solvents & membrane (filtration) based solutions.


Thanks for

That is exactly the thread I was looking for earlier, thank you!

I don’t know the initial extraction temps but I do know she’s using a 10:1 (1L crude : 10L etoh). I’m used to the standard 24 hours at 20c and wasn’t sure if speeding up the process with a deeper temp would degrade the product or have any other adverse effects.

I suggested an Agilent 1220 HPLC as a minimum for in house testing.