Sugar-like precipitate after carbon filtration

Hey everyone,

What’s this sugar-like substance precipitating from my CO2 oil?

I recently started clarifying my winterized/fat-filtered CO2 oil with activated carbon. I have since been finding a sugary precipitate that is first noticeable on the flask of my roto-evaporator (see photo). Where it really becomes noticeable is at the bottom of my beaker or roto-flask after sitting for a few days under vacuum to purge out the last bit of ethanol (see photo of it stuck to the roto-flask). Is this sugar…or?

Some details of my procedure:

I mix 10:1 EtOH:oil with activated carbon at approximately 9g carbon powder per liter of EtOH:oil mixture. This is done at 43C.

I pour a silica/ethanol slurry into a Hochstrom over a 1um filter paper and pull vacuum! to remove the carbon. I then rotavape and purge in a vac oven.

Before using carbon, I’ve never seen this stuff. I’ve been able to remove it from the oil by decanting the oil off of the beaker/flask; the sugary stuff sticks pretty firmly to the bottom (see photo of it stuck to the roto-flask) and I’m able to resuspend in ethanol and collect it onto a 1um filter paper (see photo). I’m pretty certain that it’s not silica because (1) it looks different and (2) a colleague of mine is using the same carbon filtration procedure without silica and finding the same stuff.

Any ideas would be helpful. We are making carts with this oil and I’d love to know whether it’s necessary to remove this stuff versus just mixing it back in.



Here is the stuff dried.

Is it water soluble?

Did u dab it lol

Sugars, in my experience, tend to have more color than what you showed in the pictures. I also know that I have had AC pass right through a 0.2um whatman filter paper. What I see in the picture looks an awful lot like nucleation, though.

Now for more questions. Haha. Are you using CBD or THC based biomass? Is the resin decarboxilated? Solubility tests (water vs alcohol)? Taste tests (sugars taste like sugar, albeit burnt sugar)? Do you have in-house analytics (could tell you a lot if it is indeed nucleation)?

If working with CBD that is decarbed, it could certainly be crystaline CBD, as nucleation can happen relatively quickly without the presence of solvent. Alternatively, if working with THC that has not been decarbed, the same could be true, though I have not seen it play this trick while sitting in the roto or in that short of a period without the presence of some solvent.

Yes, it is water soluble and insoluble in ethanol.

Lol, no but I considered tasting it

@Akoyeh thanks for that insight.

I get it from both CBD and THC strains, although it does appear to be strain dependent (i.e., more from some strains than others, and especially high amounts from our CBD strain). All oils were decarbed at the flower stage.

Soluble in water, not in ethanol. I haven’t tasted it - too skerd haha.

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Water solubles. If they dissolve easily in water but not in ethanol, then 100%. To take care of this, you can add a T-5 bentonite filter into your process. Just run your solution through the filter and thats that. @Shadownaught Could help you get a hold of some T-5. I went through this same exact thing about a year ago.

Thanks @G_Boe

Do you recommend T-5 as a replacement to silica, as another layer above or below the silica bed, or as a completely separate filtration process? Can you recommend an SOP?

I use T-5 in conjunction with cold ethanol washes. make a slurry of about 150g of T-5 and pour it through a 18.5cm buchner funnel to set the filter. Search bentonite in the search bar and i’m sure you can find quite a bit of info.

Not sure if you need to replace the silica, you could probably just add it as an additional step. What are you using your oil for? Are you making EHO, or are you making crude for distillate?

@G_Boe Thanks a lot. This is winterized CO2 oil mostly for carts.

Interesting that you are getting it with CO2 oil, havent seen it with that, but it surely is possible. Yea T-5 is a great resource to have.