silicone oil (super lube 50-100cst) is the cheapest of silicone oils ive found. Avacado or bran oil is a high flash point veg oil that will degrade over time but i think @Roguelab uses it.
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ive found that if you dont overload the mantle and you have a needle valve on the vac you can in a sense āride the muffinā and strip the first set of volitales. although i have fucked up more than once and bumped all the way into the receiving flask. 
im going to do a short oven time and maybe alittle in the roto also before it gets to spd on the next batch
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Iāve rigged a bench top air still also just dont like yet another stepā¦
Can I add some balsamic and have a loaf of bread handy next to it?
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cool I was just trying to eliminate another step between roto and spd for usā¦ I donāt like doing it in the spd because of the bump and volatiles but seems like 90 to 100 c for the circ bath on the roto with thermal fluid might be hell on the rotos bath heater or no?
In a mantle at 150C under vacuum, and swap the head for a bump trap. It does a great job of pulling terpenes at the same time for more efficient distillation later, especially for wiped-film. It works way better than a roto. And to second @cyclopath, you can totally scale this up to a reactor.
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honestly ive never decarbed pre distillation .I do not see the point the decarboxylation happens before we hit the thc fraction so in my opinion its saving time doing it in one step instead of two. what is the point of doing it pre distillation?
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Donāt use PG as an oil bath fluid shit will vaporize and coat everything ask me how I know LOL. But I have experiment it now with avocado oil and safflower oil this is the cheapest heating oil you can probably find that will work in your roto bath. After Iām done collecting my ethanol I crank my bath up to about 140c and let it run until all of the bubbling and vapors stop.
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As long as you let it cool a bit first. I hear 130c oil doesnāt have a great āmouth-feelā. 
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Yeah Iāve used straight up grocery store veggie oil in a pinch. It just kept making me hungry because it smelled like french fries in the lab.
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The easiest way is to use hotplate, heatgun, and overhead stirrer.
Ive been decarbing in the roto for 5 yrs with rhe same roto, if tou have an across call and ask how to reprogram it to go hotter, if its a non ai Chinese one it should go that hot anyway. Its the best way steips volitales and decarbs fast under vac
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what media are you using for thermal?
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Can you elaborate a bit on your process - time and temp - of decarb in the roto? We are kind of noobs, but we have our lab up and running and would love to take care of this step while our crude is still in the rotos. Thanks!
A reason to decarb prior is you will be flooding your vacuum oil with volatiles right before your more sensitive fraction ranges if you decarb and distill back to back.
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plus, wouldnt you be dirtying up your vapor path with fart juices and shitty volatiles before hitting your keeper fraction?
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Duratherm S
I run the roto til about 65-70c then i empty it, and dont keep anymore alcohol it will be full of terps. I turn my roto to 145c and by the rime it reaches that temp itās usually done or very close.
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