2”WFE vacuum

Hash and Stuff Distillation
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This question is about the relationship to temp and vacuum, and is based on observation on running a 2” system.

Is there a risk of limiting the boiling reaction by having a vacuum set too low during a light pass?

We are observing some of the lights are staying with the body during terpene removal steps

Here is a basic on how we are preparing material,

-45 winterization in 10:1 Roth

Rotovap bulk ethanol

Rotovap high temp- 100-145 c 30 min to 1hr

125 c @ 1.6 torr - condenser at 45c 200gram per hour feed

Then a second terpene strip pass

145c @ 700mtorr - condenser at 45c 200gram per hour feed

The crude is still very moist with lights after two passes. Not sure why, is the vacuum/temp causing the material to boil violently and some of the lights to go back into the residue side and not distill out?

Main body distillation
172 @ 300 mtorr condenser at 76c 300gram per hour feed

The distillate is really stink, dark and moves around at room temp, % is 80.

I have been going back to rotovap @145 to boil off The light materials that give the distillate the horrible smell.

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Vacuum dynamics

We notice that when keeping the vacuum fully dropped, boiling surfaces settle down,

but if we raise the vacuum and then redrop vac, a whole new pattern of bubbles forms

Backing of the vacuum I can see that more bubbles form in the feed path dripping from the flask, more bubbles when vacuum power is reduced?

Any insight is appreciated. Thank you

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When we run the vacuum at high number torr (lower vacuum power) we see more forms on material, without changing temps

Why is that?

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Are you roto vaping at a high temp under vacuum?

What’s the temp on the feed

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Rotovap goes from 100 -145c incrementally

maximum vacuum for the system (2torr)

For 1/2 hour to 1 hr

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Feed temp = 120c

reading taken from thermogun on hot silicone pad outside of flask

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Something to do with low low vac can potentially cause issues- the small residuals of target compound are so sparse that they can’t generate enough vapor pressure to free itself from the solution and you actually push the stuff deeper into solution- in an spd this is observed when the solution doesn’t stay at a rolling boil but instead seems to cycle- you’re alternating between pushing too hard on the vapor and then it reaching a critical level- flashing on and off- I can imagine that in a wiper if you’re moving the stuff through too fast that if just is too thin to really gather enough if itself to overcome the effect I’m describing.

Idk I’m totally spitballing here I have no basis for this thought other than observation and intuition.

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The guy at pope told me that you wanna actually raise the pressure when rotovapping off the last bits and turn down the flask rotation a lot- high speed turning can def cause volatiles to have a hard time leaving the solution because G force pulls del bubbles down

This was his response to the question of why wipers make red disty sometimes- improper devol

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I would run the rotavap stage longer than just one hour. Also what vacuum are you getting on cannabinoid distillation pass? If it’s 1.5 torr, that’s pretty poor.

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If your disty is readily moving around at room temp then you need to push your terp strip harder. I would decarb in the roto a little longer. Stay at 145C for an hour at least, that amount of heat in vacuum is not gonna significantly degrade material. Terp strip in the WFE, I would get my vacuum down more, decarbing more in the roto will help with this. Try 300 mtorr and 150C as starting point, raise temp if its still runny. Last, main body distillation at 172C and 300 mtorr is probably leaving a significant amount of THC in your material. I would raise temp to 180-185 at the vacuum.

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Max vacuum in the system is not 1.5 torr,

I go anywhere between 160 mtorr and 700mtorr(I know that’s really high) usually around 3-500 mtorr.

Sometime the main body pass looks dark at lower vacuum # so that is why I try to make a pass at vacuum with higher #

Also at the beginning of my run distillate is coming out thick and the stream is yellow and bulk of the material is yellow.

During the run, if there is still light compounds in the batch, the stream turns “blueish” and the pile starts to darken and sometime go red.

It seems like everyone is confirming more time on rotovap and dial back the vacuum during that phase.

Thanks for the reply.

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How fast of a feed do you recommend for the terpene strip?

When you run the main body pass that hot, are you getting darker distillation?

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The speed really depends on a lot of factors, any answer you get here will only be valid for a certain input, for example, if you get a really good deterp before WFD you can crank feed rate up a lot

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Thanks. I’m asking about the ideal sped for terpene stripping,

Too fast seems just as bad as too slow. And too slow is wasting more time,

Right now it’s going at ~200 gph

Any input welcome, thx

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I would go as fast as possible as long as your your vacuum stays consistent. You are probably looking to cut off about 10 - 20% of the weight depending on your pre-processing. More heat will contribute to darker distillate but the advantage of the wiped film is a quicker residence time so 30 seconds on the heated surface is not that big a deal. I find that trim quality, pre-processing, and not hitting too much tails in your distillation will contribute the most to aesthetic value. The amount of color change that occurs during those steps far outweighs what happens in 30 seconds on the evaporation surface.

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Something my physics professor likes to call centripetal force

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Update, I want to post the results I have come to on this thread to help future operators combing these threads.

I figured out that I was running too slow, in general.

Running on a pope feed flask, with a stop cock flow control. Two passes, will post results photos and will test as well

I’m running these settings on material that is already distilled and FULL of heads really awful stuff, fixing it to look great and have no smell.

Terpene stripping-
Feed speed- greater than 300 gph (grams per hour) and less than 450 gph

Settings -
Column temp - 162 C
Internal condenser - 62 C
Spinning blades - 6 on the motor (Pope)
Vacuum - 600-700 mtorr

Main body -
Feed speed - 225-300 gph
Column temp - 175 C
Internal condenser - 76 C
Spinning blades - 5 on the motor (Pope)
Vacuum - 300

If I were running material that hasn’t been distilled yet, I would advise a extra terpene pass at the beginning of this process (the low temp terpene pass).

I recommend first boiling off the lightest material at 145C

either under vacuum for 1.5-2 hrs or without vacuum for 30 min.

Introduce the hash oil to a short path or thin film feed flask while it is HOT, over 100C, for best results

First phase terpene strip on winterized crude -

Feed speed - 380-500 gph
Column temp - 145 C
Internal condenser - 45 C
Spinning blades - 5 on the motor (Pope)
Vacuum - 15-5 torr

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Indeed. Vacuum physics is interesting, rotational vacuum physics even more so.

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I’m not sure that’s actually accurate though. If there is a difference in density, then centrifuge action will actually cause the lighter phase to come to the surface faster, just like how a centrifuge can make cream separate from milk in an instant. Imo the real reason why running the final stage of a rotavap slower helps is that it allows time for the oil on top to fall, making the liquid flow chaotic and agitated which opens possibility for more seed points for bubbles to form.

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I agree that folding and exposure time is critical, too fast blocks that constant surface exchange as a surface “settles into place”

The vacuum and vapor pressure relationship was not obvious at first. Also I’m not a trained chemist so it’s easy to miss all kinds of details on this work