Glas-col SPD issues

Hey everyone,
So I came into the industry with little to no training on SPD. Our company bought 5L Glas-Col heating mantle and controller with USA Labs glassware.
So the past two weeks i’ve been on here researching and taking all you guy’s information into consideration when doing our runs. We are running into a problem that i have not seen on here yet.

So our controller likes to overshoot the temperatures by 10C then drop 10C below the set point. It causes our Vape Temp in our head condenser to fluctuate with the BF. I try to keep the Vape temp stable by increasing the stir bar as the BF temp goes down from its set point. Once the BF comes back up ill decrease the stirbar as vape temp will be going up again and i try to keep it from going up too much.
Usually we get heads with a 33 AVG micron vac at 120C
the strange this is that it will look to be done and when we hit 150C vape temp, thats where we get the main (or so i think) fraction. Before i started to use the stir bar to keep the VT stabilized, VT would drop well below 150 down to around 138C and then go up again when the BF would get back up to the set point (this all happens within 10 mins or so increments). The vape temp will also fluctuate about 15C up and down. We would start pulling great thick lines once the VT would start to drop, but once it got back up it will look like more heads (confused because we thought heads were done)
So we got used to using like 5-6 flasks, trying to seperate any left over heads going into mains. Our end products have been about 58 - 68% THC for first run and not that much higher after a second run. Never ending lines will be present in all of the flasks also, (i remember hearing that lines are bad).
So what am i doing wrong? Is the heat controller suppose to be like that? We trying chasing the temp up to 175C for mains but stated before, it overshoots causing the VT to go well above the THC Boiling point. (I used the Pressure-Temperature Nomograph Interactive Tool for our BP) IF i try to go to 165 BF, VT just sits below BP but yet still pulls light colored oil that stacks. Isnt that suppose to be heads? 2 months of doing this and ive yet to get it down perfectly.

Glas-col control: 104A HS112
Heat mantle : 100D TEM114


That is… hell. You’re going to want to obtain a working mantle immediately

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This was our second pass THC log. I think we went up too fast? The end product was all over the place. Heads fraction looked like it got into the mains.
We tried countering the fluctuations in the BF by going up in temp when it’s going down and going back down in set temp when BF is going back up. It works but a pain to stay on top of.

Red line is heat mantle
Orange is boiling flask temp
Light orange is vape temp
Green is the BP at current microns
Blue at the bottom is the microns

Just in case it’s hard to read or see

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A fluctuating temperature is utterly antithesis to what distillation is all about.

The controller is NOT supposed to do that. You likely aren’t doing anything wrong other than not replacing your heating mantle yesterday! Vacuum looks strong as you could hope for on a USA Lab kit


That’s what I originally thought when we first got this. We would have to ramp up extra slow just because BF would pull at the set temp but would stop pulling as it went down (VT would drop with it). We had to wait for the BF to come up and over set point before it would start pulling again. The cycle would continue until we got a nothing for a good while. Reading on here I could never relate anything that everyone else was doing to our set up. It’s very frustrating. I’ll get in contact with glad col about the controller. Thanks for the reply.

lmk if you wanna sell that malfunctioning mantle and controller cheap

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To me, it sounds like you are jumping the gun on switching to your “mains” receiving flask and catching heads. Especially if your distillate is testing sub-70%

You will see several fluctuations leading up to your thc fraction. Then it should ride steady for the duration of your mains.

Hitting volatility point of the next compound always causes temps to fluctuate, then even out until the next compound.

But I could be completely wrong lol

Do you have the manual for the controller? Is there an autotune feature?

lol your good, i know what your saying but our controller fluctuates throughout the whole process. I usually go by our vac dropping or rising for fraction changes but you could be right. We will see THC stack around the end of heads so we wait a while then switch. VT will drop below THC BP and will pick up what looks like heads (some lines will appear out of nowhere on top of good clear distillate) and then go back to stacking nicely. I’m tracking data every 10mins but with the fluctuations i’m gonna have to start tracking data every 5 mins for a more accurate graph to see whats really going on.

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YES! I just found the manual. From what ive read, we do not use the auto tuning process (never have). I would guess this could be the issue. Is the auto tuning a must to use?

I’ve never had to run through autotune but I have seen @spdking reference in another thread. I would try doing that to get your mantle temps steady. If that still doesn’t work then maybe its time to look for a new mantle or custom controller/variac.

good luck and let us know what happens!


Yeah I’ll post next time we do another Shortpath run with the auto temp. Our probe goes into a glass “casing” that’s inside the flask. Does the liquid matter for the probe to be submerged in?

We use avocado oil. Thought I’d ask to weed out any other possibilities.

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what volume do you fill your flask to when doing a run?

theres been plenty of talk on the board about controller probe placement. many feel the best place to put the controller probe is between the mantle and glass flask.

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We try to build up a min of 1500g of oil. We’ve done a 800g run also. I’ve read on here that the amount doesn’t really matter which lead me to doing 800g twice.

Makes sense for sure. I was thinking temp of the oil has to heat the glass, that has to heat the oil, then heat the probe. My thought was all that layers of heating is causing a LAG in temperature reading. IMO.

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Synthetic vacuum oil works best. Auto tune should be done around half way full bc tuning behaves differently with different fluid amounts.


This can be very unsafe.


Thanks for the tips man! Once we get it done I’ll post results. Do you have any tips on doing the auto tune like a set temp to start on, and should I start it once it gets to that set temp or in the beginning when it’s heating up? Sorry for all the questions. Our lab director got let go over two months ago and I’m having to pick up all the slack around here as the lead lab tech.

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Let’s see the still @Toeknee956 looks like a great quality build!