Looking for advice/help on first and second pass

Hi all,

Looking for some help on my SPD process. Got results back for a first and second pass from the lab, and the results were not as great as I would have hoped😬. 1st pass was ~61% d-9 and ~66% TAC.

2nd pass from different starting material was ~71%d-9 and ~79%TAC.

Next round of testing, I will also be sending the crude, and everything from the same starting material. Crude, 1st and 2nd.

5L full bore system I pieced together, 45/50 head to 29/42 with a single e2m30 at the end.

Following the GLG first pass SOP, collecting mains from 165-185C while the system pressure at the pump sits between 30-50 micron.

Here is what we’re up to:

ISO extracted machine trim (I know I should be using cold etho, working on it).

Decarbed on the mag stirrer then scrubbed with T41 and degummed with DGE as per CarbonChemistry website SOP.

Dissolved in hexane and vacuum filtered. Then brine wash (10% salt by volume, distilled water) in sep funnels with low, high and neutral PH.

Evap hexane and redissolve in ISO to 10:1 and into the freezer for ~36hrs to -25C. (Can I sublimate dry ice to lower temps further? I don’t want it to throw off the PH or anything weird. Or chill my containers in a cooler/chest with the dry ice around it? I think it should be colder, especially with ISO instead of etoh.) Vacuum filter, evap, into the BF.

Then GLG SPD first pass SOP.

I have read here on the forum that there is a 2nd pass SOP on the GLG site but I don’t see it on the shared drive. Just two of the same versions of the first pass SOP and the Wiper SOP.

System pressure sat around 20micron or less at the pump during second pass I think but wasnt really sure where I should be collecting the main body during that second pass. The pressure being slightly lower, how should I tighten my collection tolerances in terms of the vapour temperature for the next run? The second pass I did, I just collected at the same temperatures (165-185) :man_shrugging:
but the WFE SOP on there makes me think i should try for 170-180 maybe?

What else can i be doing to help maximize potency without sacrificing yields unnecessarily?

Working on taking vapour temp during each run and graphing for reference. is it possible to pull data from LS bullseye vacuum gauge? there is a USB port, Non Bluetooth version.

Things on my list to get:
Ultra low freezer
Pressure filtration
Fraction finder

Here is the second pass. Doesn’t have a smell
or taste, I dunno.

Here is the first pass

TIA everyone


It appears to me that your distillate has a lot of striations in it. This generally means that there are other compounds within your distillate, and this can be confirmed through a C of A.

I tend to over-winterize my oil, but here is my recommendation. Dilute oil 1:10 in 190 proof ethanol. Allow your solution to sit at room temp for at least 12 hours, then filter it through a 30um filter (or non-bleached coffee filter) and a layer of celite 545. Then take your filtered solution and put it in a freezer around 0f for 12-24 hours. Filter this solution through a 10-30um paper and a layer of celite 545. Take your filtered solution and put it in the coldest freezer possible,-85c ideally, for 24 hours. Filter the solution over 1um fitler paper and celite 545. Then recover your ethanol, perform degum, and repeat the steps. Many people have written up more robust winterization procedures, and you should look them up and be more familiar with them. My write-up is rough, but will help you improve.

On average our distillate is 90%+ D9THC, but we use spinning band distillation. You may still need two passes to hit above 90% D9THC with a shortpath.

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How are you making your crude, ethanol extraction? If you are new to short path distillation, it’s probably just a matter of you getting a feel for when to switch your receiver to collect the cannabinoid fraction. There is a lot of junk that boils just before it that you want to throw into waste, people call this stuff “heads”. Being patient and making sure your heads gets into waste or a separate collection vessel from your “main body” is the most important point, more so than all the fancy hexane/saline washes and magic clays that can be used. In fact, avoid all those when you are starting since they don’t really improve potency. After you have gotten your potency in the right range, you can play with those other methods to try and improve the color a bit.

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This is actually great advice.

Making sure you get clean fractions is priority #1.

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i understand what you mean and have noticed that before too, I will try a more in depth winterization process as you suggested.

Using isopropyl right now, but working on getting some ethanol for winterization at the very least.
It actually makes me feel better that I should just scrap the fancy stuff and until the fractions get a little bit tighter. I’ll probably get more done that way too.

I was thinking about adding an isolation valve or something, so I can experiment more with what’s coming over and when by taking smaller samples from each range and hopefully help accelerate my learning curve that way. As well as extensive record keeping and consistent testing of batches from here on out.

Much appreciated, the both of you.

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You are pulling a really good vacuum on your setup if you are down to 30-50 microns, I would usually distill cannabinoids at ten times that pressure, so considerably higher temps (180-198C to start cannabinoid fraction). The tell tale sign with most crude was the “green slime” fraction. This starts before the cannabinoids come over. It’s sometimes blue if you used clays or carbon. I think whatever this stuff is, it’s actually synthesized in vitro in the process of heating up your flask and distilling out the terpenes and lower bp stuff. In any case, you want to let that slime distill for a long time until it stops dripping before bumping up the temp slightly more to pull over your cannabinoids. When the cannabinoids do start coming over, you might want to let the first 30ml-50ml or so go into your waste stream, because they might not be super pure just yet. Sometimes you have more or less luck hitting purity even with good practices based on the biomass your crude came from.

I personally feel like super duper vacuum depth, fancy pre-treatments, and quality of glassware really doesn’t matter as long as you are doing your best to fractionate according to basic principles of distillation. I once consulted for some friends, they had already bought garbage ass Chinese glass that was leaky as hell (to atmosphere) when running. I shook my head, but helped them anyway. Due to the system pressure, we had to distill cannabinoids around 213C (like in the “old days” of OSS Youtube videos lol) I did my best and sure enough the final product was 98% total cannabinoids! I was surprised about that. The starting material was some pretty “average good” BHO they acquired from a friend. We winterized it and that was all for the pre-treatment.

EDIT: And the last part of learning the process is knowing when to stop! You will naturally need to raise the temp a bit to keep that main body of THC coming over during the process, but you only want to do this so much. This is more of a qualitative process than anything else based on color of the reflux (significant yellowing). @breakingdabs is a pro who has shared information on this extensively

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those look to be the jars to me…

although given the potency you’re probably on point.

How are you getting the material tested? Finding a good lab isn’t easy everywhere.

I wonder if you are getting any isomerization from your T-41 scrub. Maybe making something they don’t test for. How hot is your scrub and for how long?

T-41 is pretty acidic I believe so that would make sense

I pull body 197 - 204 area 165-185 I don’t think would ever work for me.

Nice vac depth! Once you figure it out, you’ll hit good numbers for sure. Your first pass looks good tho. I’d also suggest you shop labs if you have more than one available. I’ve found major differences when I sent the same sample to 2 different labs.

Does your lab test for d8 THC? Can you request chromatograms? It’s possible that the T41 is causing isomerization.

I’d try winterizing colder. Maybe winterize in MeOH. Wish I had more info to offer, but I actually have more questions than answers - if you don’t mind:

  1. When you do your brine wash and pH swing, do you pull any color into the aqueous layer? Mine always comes out clear with the organic layer as dark as ever.

  2. So do you degum by heating distillate and hot water and stirring in hydrated enzyme incubating at 40C for ~1hr? Do you have trouble stirring the material at 40C? I can’t get my stir bar to spin at that temp. Or do you degum in a solvent?

  3. Do you notice a significant color change after your T41 scrub? You do a “dry scrub” by adding T41 to distillate and stirring with heat? Then extract into hexane for filtration?


Thanks, I am keeping the green and blue slime out of the main body and it all seems to be in the heads flask below my dewar trap. I’ll try waiting a little longer before switching to mains.

The boiling flask is basically empty by the time I’m hitting 195-210 on vapour temperatures. Hardly goes above 205C.

@cyclopath yea the jars are textured also. A parquet floor pattern sorta.

Some certified lab from the government website. I am also going to get it tested elsewhere and was thinking of Also getting a TLC kit just so I can get a rough idea of where I’m at without having to wait a week or more for results.

Hot scrub around 90C for 30 mins.

Here is the results from the lab. Will try and skip the hot scrub and get next batch tested.

Yea it pulls a ton of red out on the high ph wash

I just put it in my hot water bath for the roto at 40C with the hot distilled water and stir with a silicone thing periodically.

Haven’t noticed significant difference from the starting material to after the hot scrub. But yea, a dry scrub. Mix with oil then hexane and filter.

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I would make a batch of crude, scrub half, and dont scrub the other half. Distill them separately, and compare the results. Just do your best to try and work with the same distillation sop.

Could be many things, but this will at least determine if the hot scrub is the culprit.

I’m really not trying to be a jerk, but what the heck is going on with your SSOP’s for your lab?

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Yea, I noticed that after looking at the image a few times. It is hard to tell though.

My buddy has a personal use production grow (not for commercial sale) and there lots of machine trim that’s been piling up and more coming all the time from each harvest.

I figured I might as well as put some of that “waste material” (recycling!) to work and learn a new skill set.

Just trying to figure all this out. Been piecing things together for a while now and trying to keep my spending fairly lean. After a few tries, am looking for some feedback on what I’ve been doing right/wrong, where I’m wasting my initial efforts and how I might improve the quality and efficiency of my outputs.

I’d love to be able to leverage a learned skill set into some sort of eventual employment or something. Even if I don’t, at least it’s still awesome.

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That’s awesome! I’ve considered something very similar