How cold is cold enough? (BHO)

I’m in the process of designing a hydrocarbon lab buildout (for the first time) and am looking for extractor input on chilling down material columns, in-line dewax columns, etc.

Chillers are big purchases, I’ve always seen the advice of getting one better than you think you need.

But how big is the difference between soaking fresh frozen in 100% butane at -15C versus -80C? I have never worked a system so cold and don’t have that sort of experience. I understand that colder gases limit solubility, reducing unwanted absorption targets like lipids/fats, chlorphyll, etc., potentially producing a nicer quality final product (less fats in live resin = less nucleation targets = larger THCA crystals) But for $35k into a -90C chiller, what functional differences am I seeing in dropping to such extreme temps? Does the product really come out that much nicer? Am I reducing my soak times (due to faster wax extrusion) or slowing them (due to reduced solubility)?

Feeling a little lost, thanks in advance for the help, insight, and experiences

I work at lab now that produces Live products and uses a PX1 system chilled to -15C.


Idk but I heard that stripping works better than soaking (even with water hash) but it’s all preference


-30C seems to be the magic number at my spot. -29C and it all dissolves and goes right through the filters.


I kind of agree that -30 is a good target. It also depends on the solvent blend you are using, and also the design of your system. You also have to consider if you are using CRC as part of your process.

-20 is what I would get my solvent and extraction chambers too and it was good enough to make non-sticky shatter and high potency out of biomass that was machine processed in the low teens in potency. It wasn’t cold enough in my opinion since any problems with the trim like disease or overprocessed, old whatever… I would make some pretty gross wax that would need refining.

I’ve also used a system that blew liquid CO2 into the jackets and relied on pressure release valves to keep the machine from catastrophically failing. Terrifying work environment aside, the shatter from this process was more consistent, but not crystal clear or any better than what I could make fairly consistently at -20. I wouldn’t use liquid CO2 for cryo ever again, and I left that company after 3 days because the technician training me destroyed a 10k double jacketed solvent tank with liquid co2 since the pressure release valves aren’t a safety mechanism when they blocked or frozen shut. . . . The owner’s rational was that liquid CO2 was cheaper than buying the correct chillers and powering them.

I’ve also found that chillers are pretty limited in how many different units you can have them really work with unless they are way overpowered for the equipment it’s running… and another consideration is the length of the chiller lines…


-70 to -50 gets the solvent so cold it lowers the solubility of it…and get the material that cold also so it doesn’t warm going through the columns. Then you’ll grab as less fats,wax, and lipids as possible


I sure havent found any advantages of running -90C, or -80C for production purposes unless fractional extraction is your goal. Solvent gets pretty slush around those temps. -80C capability is cool to have for R/D and IG i guess…

Also worth noting- A key with chillers is cooling capacity, just cause it goes to -90C doesnt mean it can control your process at -90C. Theres a spreadsheet calc shared on the forum that can help determine your cooling capacity reqs (at 100% efficiency) as well as capacity specs on some Cryodax chiller models.

For me, live resin quality has alot to do with material prep/handling and never getting near 0C, but that dont mean -80C will give you the best results. Just dont let that bio even think about thawing!

-40 has been the traditional target temp, but im starting to wonder how advantageous running that cold actually is vs the higher end of the subzero range like -10C. The cost of maintaining cooling on a larger processes to -40 isnt trivial.


We need to summon some resources here @cyclopath @Photon_noir


If you’re spending someone else’s money and want to be sure you are gonna kick ass while also getting exceptional customer service I suggest huber.


You actually don’t want to go below the -65C mark for the purposes of THCa extraction for n-butane (or somewhere around -40 to -50 for propane, but I’ll speak mostly on n-butane here). However, at that temp or even up to -40C, you can do very long soak times while still leaving out the undesirables for the most part. Still, pretty much everyone I’ve worked with has had better experiences simply flushing their material column through with the proper ratio of solvent and no soak time whatsoever. This is ideal because all our goodies are on the outside of the biomass so any penetration into the biomass is undesirable. Depending on your quality of material and whether you are CRC’ing or not, and what your solvent choice is, you shouldn’t need to go below -20 to -40 C with no soak time (I’ve seen room temp runs come out high quality too, but it becomes very difficult to maintain consistency in your end product with variable input material and room temp solvent).

Also, most of y’all can more than satisfy your condensing requirements for recovery with a water chiller running 5-10°C, if you’re interested in this I can calculate what you’d need to make that happen.


-50 or below for concentrates you do NOT want to CRC very much, if at all. You can run between -10 to -40 and use a little more of some medias to take out the relative difference in color. You loose some wax weight running colder, but also gain terpenes if your collection is not too hot for recovery (active or passive).

I have done numerous installs using Hubers. The 915’s, 815’s etc…

They work great, but you need to know what you are doing with load capacities.

You also need to have a good idea of what type of concentrates you will be making. Real high end shit, or middle market stuff. Only high end shit ever gets ran really really cold below like -50.


Thanks for the heads-up @Sidco_Cat !

For fresh-frozen, I think most folks here have good advice on the subject, but perhaps @CollectiveObjective & @Krative said it most succinctly, above.

The water in the plant is not just water. It contains loads of solutes, which depress its melting point. Pre-freezing the biomass sufficiently is best performed in a blast freezer or even LN2 to freeze it without allowing ice crystals to grow inside the cells, causing cell wall damage. However, this is usually not feasible with larger scale crops on most processor’s budgets.

So instead, most just prefer to use a chest-style cryofreezer. This gets the job done swiftly enough, and thoroughly enough to allow some transport time from freezer to columns without thawing.
It helps to allow a little wilt-drying, so the cells lose turgor, but not to the point where flowers and leaves all lay flat.
Still, try to keep the biomass as fluffy as possible while freezing… Crushing or compressing it is highly counterproductive. Use (preferably plastic) wire shelving to support socks of biomass weight off of each other as they lay horizontal.

The actual columns of a fresh-frozen BHO system should be no more than 36" long, and evenly chilled (jacket coolant fluid on a parallel manifold, entering and exiting at opposite ends, flowing bottom to top) to between -25°C & -60°C… no warmer, no colder.


Does all this advice, aside from the specific temperatures, apply to ethanol extractions as well?


Can you go into the logic or data behind this?

Please and thank you!!


@Krative , Not the advice I wrote… I would NOT advise running fresh frozen biomass with alcohol, since the alcohols we use are very effective water miscible de-icing (melting point depressing) compounds!

@cyclopath This is based entirely on my experience and trusted anecdotal evidence from clients & colleagues. Honestly, I would recommend chilled 6"Φ biomass columns no longer than 24", but I think most people in production environments would ignore that advice… so I compromise, setting the maximum at the next standard sanitary tube length up: 36". The reasoning for this is to achieve a balance of pro & con effects with practicality in mind. Longer actively frozen columns of biomass simply have way too much solvent “holdup volume”; to be frank, they are TOO wasteful of solvent, time and/or money! Also, the thermodynamics are such that the extracted THCa can even begin to precipitate from the chilled alkane solution before it can exit to the collection pot! I know you have seen this occur, first-hand, in the small cotton depth filters on even 36" columns! If you think about the biomass columns as the huge, ice-filled Liebig condensers they are, these cost-prohibitive solvent holdup volume/time & thermo-kinetic problems should become apparent. Does that reminder help explain my logic?


yeah, but I thought maybe they were just doing it wrong…. :shushing_face:


While “doing it wrong” can certainly happen with even the most efficiently configured equipment, you may also remember how much I had to modify that pre-built system, just to eek out what little efficiency we could get from it. Both the fresh frozen format and improper extraction system configuration are ardent enemies of the “3 Es of manufacturing”: Efficiency, Efficacy & Economy. Cost-effective, high quality, fresh frozen biomass extraction is actually one of the most difficult accomplishments in this industry, imo.


SO if you were running pure propane and your goal was to make crumble, wouldn’t it be counterproductive to use a chiller to achieve temps of -20 and lower?

When people straight up freeze material, without meaningful reduction in water content, it always makes me anxious about my timing, to ensure thawing and water draw doesn’t happen. I honestly can’t stand fresh frozen, it requires me be on my toes and temps.

Of course I am running like an ape compared to you guys, I just have a dry ice coil and dry ice jacket, I try to run fast and cold, no soak times, and if I have to I run my hot loop to scrub as much of the material as possible. @Photon_noir described what I have seen time and time again through my sight glass at the bottom of the column, if I see residuals, or noticeable saturation, I start to recycle my vapor flow to catch anything I can.

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Hi! Does this short(24") and wide(6") column design also apply to a dry material? And does it have to be also actively chilled, when dry material is being used(7-14 days old: “fresh dryed”) or can it be just pre-chilled jacketed(for vaccume isulation) collumn?

Thank you for any answer!

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-40C or colder.

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