Starting Grams of materials for small run

Hi All,

I want to do my first SPD run, but don’t want to waist too much of my material.

I’m extracting with ethanol, -40c that part I think I’m not sucking that much anymore :stuck_out_tongue:
(I say -40c but I get the ethanol to -70c, the material stays at -40c before wash)

I will remove ethanol with distillation, not rotovap.

My questions are:

- How much ethanol do I remove? Does it have to be a sticky consistency?
I have 2000ml of solution.
I have been reading that I should leave around 8% of the total solution

- How much crude can I do a test run with?
I was thinking of trying with 100ml but i have no idea if this is nonsense.
My setup is a 2L Flask.

If you can point me to a text I can read or any info it would be amazing.

Thanks for any help, really appreciate it.


I am not a scientist, just a professional hash maker. These are not facts, but my experiences in doing this every day:

When you say you’ll be removing your solvent via distillation, what does that mean exactly? A rotovap is a distiller… I guess I’m just making sure you’re not planning on doing this in your boiling flask.

  • How much ethanol do I remove? Does it have to be a sticky consistency?
    Doesn’t matter. I’d get out as much as you can to protect you vacuum pump during distillation.

  • How much crude can I do a test run with?
    I would do at least 500g. You won’t learn a lot otherwise.
    The beauty of this process is that you can always just start over. If you get bad separation you can always just dump somethings/everything back in and re-distill. Worst that can happen is a little cannabanoid conversion.


Thanks a lot really.

I use the boiling flask BUT with a long water cold condenser.

Are you using a vacuum to assist?

Yes, I have a Leybold D10E, with a cold trap.

I set the chiller to around 0c , it is a 12inch condenser to remove the ethanol.

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You’re all set :+1:

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You might get problems with less than 500ml in the boiling flask to get your vapor pressure high enough to get things gooing
Give iT a shot but watch your temps and your flask If You see smoke like vapors to little to start
Good luck injoy the ride i was mesmerized bij the colors that poped up once in a while


The minimal run that I’ll put in my boiling flask is 10% capacity

I wouldn’t waste time with a run like that in your 2 L flask. You should put 1 L of crude or 50% fill. Look into the way beaker sets up his rig for micro distillation. He has a much shorter path than a “short path”. Trying to move that 100 ml up your reflux might take too much heat creating degradation of your target molecules.

Your solvent recovery sounds fine but don’t use a nice pump like an Edward’s, use a diaphragm pump like welch


How deep is the vacuum on the welch diafragm ? Most diafragms i know don t go as deep
And in the destillate game vacuum is everything good vacuum makes the ride easyer and more “controlable” deu to the cfm - preassure stabels fast
And i am deffinatly sure that even If 50% of the starting material evaporates of in the Edwards she still runs > oil change and ready to go

It’s not for distilling high boiling point compounds but rather for low BP “volatiles”


Understandable completely. However let me suggest that cutting back on the starting compound as a way to test the waters is only one prudent way to proceed. On any given run using a traditional SPD the boiling flask is best to start with half full if possible but certainly as close as you can get. I say “best” because what you learn from your first run then can be applied to your next more readily. Starting with a limited amount of crude will teach you only how to run a limited amount and not really how to proceed with subsequent runs.

So perhaps another way to test the waters without undue risk is rather to limit your starting temperature(s) you plan to use ultimately instead. Then when the temperature is achieved and you can see how things are running and test what vacuum level you can hold (or not hold) then you can edge the tmeperature up in increments to creep up on the target settings. Let us say you decide to shut down instead. You will have lost almost nothing by starting out cooler and edging to warmer. Then as a problem arises you can tap the experts here or other places an reconfigure as needed and proceed with your run.

I would go so far even as to foresake any sort of degumming or ph adjustments or any such other well known and used mechanism and stick ONLY to heat, vacuum, and patience on a first run which again is an option as a start to “see” how things proceed without them (I use no scrubs or ph adjustments at all). Once you get a run under your belt with just the basics and can dial in the temp and vacuum then at that point I would suggest adding the next step in your planned or suggested SOP of refinement.

When you start with a very limited amount your pressures and temps will be very much different than a regular run. Another obvious option of course is to start with a flask half full but a flask that is only say 250 ml instead. Any smaller size flask can be run in a larger mantle with enough fiberglass cloth or sand to fill in the extra space. I have used both sand and fiberglass to run 50ml flasks in my old 250 ml mantle. Just put the flask in and dump sand right into the flask. Use a shop vac to remove if needed. Then you will be emulating a larger run and normally I would expect the values to be consitent across both smaller and larger boiling flasks.

I leverage very small devices to do gram/ounce size runs and would not attempt a regular SPD on a greatly reduced flask because you end up cooking the same molecules over and over just in order to heat the upper part of the glass on your SPD. In a traditional SPD the compound itself is the carrier of heat for the upper thermal stack and if you severley limit your system in terms of reduced thermal carrying capacity then what is left over in the boiling flask must carry out that duty with a limited number of molecules for doing this. The problems begin to stack up against you.





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Put the sand into the flask?

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You missed @beaker, as we do.

R.i.P @beaker

So, small flask, big mantle; sand is to fill the extra space…

Or see what others have said on the subject of sand in ones mantle (@spdking is not a fan)


This is dangerous and has over shooting issues.

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This (*can) be dangerous and has (*increased liklihood) of overshooting issues. Most anything we do with vacuum, heat, pressure, and/or solvent choice presents very real dangers.


Yes but the process of Wich heat is distributed against a insulator(sand bed) is a dangerous process and also can cause damage to the glass/mantle. The core thermometer doesn’t actually see temps at a higher rate than without the sand. Meaning it takes alot of energy to heat up such a mass prior to transferring the energy.


The late, great @Beaker used to purge solvents with fire in his home lab (not recommended for anyone reading). While yes, very dangerous, he did it in a controlled and relatively predictable manner. Dangers can be mitigated and prevented with thought and good practice. I very much appreciate his novel approach, albeit a dangerous one.

People have and will continue to do dangerous things when extracting and purifying cannbis extract. Every time you place something under vacuum or pressure, you are introducing serious dangers and risks. Those risks can be mitigated with good practice. Knowing the limitations of the practice in question can help, too. Putting a 500ml flask in a 20L mantle is not what we’re necessarily presenting (yes, that would be very likely to be problematic).

Most everything we do in the lab is dangerous. Not everyone can afford the best tool for the job when it is needed, and parts on hand may be as good as some of us will ever get. If you have another solution, we’re all ears. If not, maybe help mitigate the risks for those attempting this tek (if you can really call it that). I’m sure there’s something in that noggin that can help more than “don’t do it; it’s dangerous”.


Would these be more appropriate?

Or would you recommend crumpled Alu foil over sand as well?