Residue Rework

Hello everyone, long time follower of Future 4200 first time poster.

I am currently working with some CBD material sent from a client that has gone through poor extraction techniques. Firstly it went through a warm ethanol extraction that pulled a lot of sugars. It was then ran through filtration at both 5μm and 0.75 μm however this filtration was done at room temperature. During solvent recovery high temps of 150°C were achieved with vacuum as low at 30 mbar. First pass wiped film distillation ran as usual however second pass resulted in burnt sugars that quickly built up on the evaporator column that caused gear pumps in the residue line to seize. To maintain a better flow on the residue side, feed rate was increased however it was known that a decent amount of cannabinoid was bypassing the evaporator and ending up in the residue.

We are now left with the dilemma of 20%-30% of our cannabinoids being locked up in very thick residue that when left to cool has the consistency of glass. Typically I would suggest utilizing liquid-liquid separation however when the residue is “melted down” for 12hours @ 100°C it still remains glass like with some parts being the consistency of thick molasses. As we know majority of our residue is sugar what is the most effective way of removing cannabinoid from an almost solid sugar/ glass type residue?

Any input would be greatly appreciated.



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Run water or methanol/water as a flushing fluid


Put it in a reaction vessel with water, mix it with heat for a couple hours. Then let it sit overnight to separate. You should be able to clean those sugars out.


Good suggestion, thank you.

My only concern is with the amount of sugars and undesirables in our material I don’t want that to settle and be difficult to fully clean out of the reactor. Another similar idea I had would be to utilize the jacketed reactor at a hot temp, add water and mix. Then leave to separate but keep the reactor hot. Hopefully since the sugar/water would be more dense it would settle to the bottom and can be poured off almost like a separatory funnel.

Also seeing how our residue is 80% sugar and undesirables what ratio of water should be used? Maybe 80% water to weight of residue? Should ethanol also be added to assist with the collection of cannabinoids?

What are your thoughts?

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Just do what I said lol


Where I am located Methanol is not allowed for use in extraction but thanks for the suggestion

Water will dissolve the sugar (and other water-soluable undesirables) thus making the sugar not solid anymore. What is left, should become more viscous under heat (like normal residue).

You should see two distinct phases in your reactor. The aqueous phase with your sugar dissolved in it and your non-polar residue. Siphon off the residue and it should act like normal residue and liquify much easier under moderate heat.

EDIT: DO NOT ADD ETHANOL. This will defeat the purpose of performing the water wash and allow cannabinoids to dissolve in the ethanol/water solution along with sugar. This is how you got the sugars out of the plant in the first place, because they were extracted using ethanol. The reason water-only would work better is because sugars REALLY want to dissolve in water, but cannabinoids don’t, so you can effectively separate them.


I don’t know how much you have - but I’m always looking at a 2:1 water mixture when I do things warm. and a 4:1 when I do things refrigerated. I don’t know what others do - my logic for this is I don’t want to leave things behind, I leave less behind when its warm anyway, so I don’t need as much. When its cold I need quite a bit more to capture everything.

I know some people will do the rinse multiple times to get everything - knowing you will lose a little bit every time - because you can’t separate perfectly each time, etc.

@mcpikeig is 100% right not to add ethanol until after you have separated our your sugars. You don’t have to use methanol… but you do have to use something that isn’t miscible with water. You decide what you want to use for this - here’s a table from Sigma that I still use like 20 years later.

Once you get things separated, you might still have water in there, just a bit. So I’d also do a rinse with ethanol AFTER SUGARS ARE SEPARATE - to capture the water and pull it off via evaporation with your solvent. I’d filter at this point as well - just in case you have any “char” or other solid bits left behind.

And then back into the wiper.

Good luck and let us know how it turns out.


Thanks for the great feedback!

I’m sitting on about 80kg of residue that’s probably sitting at about 20%-30% cannabinoid.

I’m just working on small amounts at this time as our larger assets are being assigned to upcoming projects but any progress I make I will post.

If I was to use Heptane or Pentane as my nonpolar, what amount would you recommend per liter of residue given that my residue is 80% undesirable?

80% undesirables. I’d probably do a 1:2 - with multiple washes, rinses until I don’t get anything in my water layer anymore. I know lots of people here also control for pH when doing these rinses. And some people also utilize brine.

There was a bit of consensus about using heptane which evaporates slower for these things instead of using pentane.

I’d do a liter first - especially if you don’t actually know the 20-30% ratio. You want to have at least enough heptane to dissolve all of the stuff you want to keep and at least enough water to dissolve all the stuff you want to take out. Looks like you’ll need a 1:4 (pentane/water) ratio based on the information you provide here. You can totally do 1:1 - it will just mean you may have to do it multiple times to get all the sugars out.

I remember one time a peer did this and thought he had 70% water solubles. Turned out he didn’t have water solubles at all but had a crap ton of nasty lipids instead that could have been sorted out via ethanol and a freezer. They burned a lot at higher temps. So if you are not - certain, I’d do a little side test to make sure what you have is water soluble stuff and not just a mix of other fats and crap.


I mean I know there’s a lot of “crap” in this material however when we did any winterization tests no lipids or fats seemed to separate off, actually I attributed all the sugars to the lack of lipids as if the material was properly winterized and filtered the first time most of those sugars would have been able to be filtered out with the fats.

I know most of the residue is water soluble as when it was charring up in our evaporator it was very easily removed with a few sprays of water.

It would be nice if testing existed that could tell us what other than cannabinoid, terps, solvent, pesticide, ect. is in the residue material as I suspect the composition of that material must change a few times as it goes through processing.

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Use ethanol, water than ethanol. It always works for me.

Thanks so much for all the input. I was able to implement a heptane/water liquid-liquid separation. As I didn’t have a separatory funnel I just utilized a 2L bottle to observe the separation and see how much of my water solubles get washed off. I will be going forward with utilizing my AI reactor as a large separatory funnel in a few months once I can get some documentation in place. I will keep you guys updated!


pro tip


Looks pretty gross

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Yes, lots of water solubles

Best to extract with heptane in the first place imo

good luck

Your sugars will be at the top of your lower layer so make sure you wash that out of the reactor. The next wash may still contain more undesirables if you are performing a 2nd wash. Have you checked the ph of both layers?

Call me