Winterizing smarter, not harder

Trying to work smarter not harder. Trying to at least…

Running 10:1 ratio etoh to crude, hemp extracted at ambient temps so plenty of waxes and lipids to deal with. Given recent extractions I’m going to have 400+ gallons of etoh/crude mix to go thru, so I’m trying to expedite the process as much as humanly possible. I have a couple nice lab chillers that can get down to -80C with reactors holding ~35 gal of etoh mix.

Before anyone screams “SAMBO!” I like what he’s got, but at current time I can’t manage the 12 grand for the 800MM trolley. Understanding that it has considerably more surface area than what I’ve got, I’d like to buy one in the future, but I’d like to improve my speed as best I can given the tools I have available without buying too much new equipment (gotta get paid for this batch before I can justify throwing another ten grand at the lab). Have no problem buying additional/different filter medias if it will make my process faster or easier.

I’ve got an 18" benchtop Buchner like the Bel-air units and several smaller ones (6-8") available.
Was trying to do first pass winterization with coffee filters and found that they plug very quickly even running at higher temperatures.

After seeing another post here and getting frustrated with the lack of speed in my winterization process, decided to try a first pass using an 8" Buchner, stainless screen on bottom and some rough grit aluminum oxide which grabbed a significant amount of fats in my first pass thru, using a 2" media bed over 20 mesh stainless screen. I think I’m going to adjust my mesh size of alox and will probably grab even more that way.

For second pass, I have tried a few different grades of the “coffee filter” style filters and they seem to plug up fast regardless of temperature and are really too fragile to scrape the fats off with a spatula without tearing.

Seems to me that without scraping the fats off, you get an interlocked coagulation of fats which nearly halt any flow thru whatever filter media you are using. If you have any edge leaks in your Buchner or benchtop a sufficiently thick layer of fats will exacerbate them and probably slow your pitiful flow even further, all the while hissing or whistling annoyingly.

The 18" Bel-Art style benchtop Buchner I’m using definitely has some edge leaks. I think in an ideal world they would have included an additional poly ring (like the one that supports the filter media, but slightly smaller OD, split and no perforated center) to use to pinch the filter media against the walls of the filter so that edge leaks aren’t so prevalent. Probably going to try and make my own if I can source some polypropylene sheet or a large enough poly cutting board tomorrow.

Coworker brought me some sort of food grade poly mesh bag to try, cut it up and flattened it out along the bottom of this filter, works great, tough enough that I can scrape it with a spatula without tearing it up and having leaks, only problem is he doesn’t remember where he got them from. Le sigh. Anyone have any ideas where this might have come from? He seems to remember that it was an MJ related item but not who he bought it from.

I’m also curious from those who do more winterization than I do, does it make more sense to let your filter bed run “dry” and then rinse the fats with chilled ethanol to get that “white cake” fats, or scrape fats into a bucket and when enough have accumulated then reprocess them (thinking of homogenizing 1:1 with cold ethanol, let sit overnight in a cryo freezer at -60 and then pour off the ethanol and any oils riding along with it)? I’m wondering because it seems like if I interrupt filtration every 20 mins to let it run dry and rinse with cold ethanol I’m going to go thru a lot of cold ethanol and drastically slow my filtration time.


If the problem you encounter is the trouble you cite with thin media tearing when you scrape it then a thin layer of alumina or sand and such on top of the filter will solve that. I scrape the top layer off my fine grit alumina bed all the time as it clogs. Just reach in with a spoon and scoop off the top layer as the bed of wax builds up. Easy peasy.

The build up of wax as a filtering matrix on its own is fundamental to why sand filtration is so effective. Sand filters have been used a very long time. Septic systems use them, pool filters use them, and myriad other apps. A sand filter of proper grit and packing will outperform a paper filter of any kind every single time but as just a layer on top of a paper filter it is effective just because of ease of clean up.


i have 3 of the bel art buchner filters. 2 of the 18" and 1 smaller one. ALL 3 either leak through the seal as mentioned or the poly sheet wrapped around them started coming undone. I took some ratcheting straps, wrapped it around the outside and tightened as tight as possible specifically around the ring the filter is held with some success…hate those things though…or i shove something under it and filter at an angle to avoid where i know the leak is…hell my smaller one somehow developed like a 5 inch crack right above the fixed filter…

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An update:

I tried the ratchet strap thing on my Bel-Art. I do think it reduces leakage at the very outside edge of the main grate that the filter sits on, but it doesn’t fundamentally change the problem I was having with leakage at the outside edge of the coffee filter (where the coffee filter material makes the transition from horizontal to vertical). It does seem to make the coffee filter suck to the grate in the middle a bit better though.

Wanting to do better than that, I spent the money and bought a 2’x4’ piece of 1/4" poly sheet from a local distributor (Professional Plastics), roughed it out with a router and then turned it to diameter on my big metal lathe, so it pinches fairly tight with 1-2x 24" coffee filters on its OD when pushed into the bel-art. It’s about 3/4" radius.

This made a noticeable difference on both the vac level maintained in the tank that the liquid was being pulled to and flowrate.

I did also talked Utah Biodiesel and got myself a couple of the poly bag filters to try out. Lowest they go is 100 micron, which won’t do for final filtration but it is definitely right for an early/roughing pass. Still waiting to hear back from them on what they want for a material roll instead of a finished product.

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I think you might be having issues with the wrong diameter of filter paper. In regular (porcelain) Büchner funnels, you use a paper sized to just cover the holes in the perforated plate, so vacuum can suck the paper down flat. I’ve never seen a larger paper (that transitions to the vertical wall) used that way. Also, setting with a small amount of water first really helps the paper seal down onto the plate.


Interesting idea. I have been thinking of doing the same with making a poly print so slip inside the I.D. of my buchner ro pinch the papers against the fritt and inside wall. Also sells filter bags down to 1 micron that will fit the 2L glass buchners and the bvv refinement filters and hochstrom

I was using ethanol in a spray bottle to wet the filter to help with adhesion before adding my solution to be filtered, I definitely agree with that. I don’t think I’d want to use water just because I’m reusing my (expensive!) ethanol and don’t want it to absorb that water and have to worry about scrubbing water out of my solvent later.

If you’re using coffee filters as many on here appear to be, they seem to have trouble laying completely flat on the perforated surface like dedicated filter paper/media does - this can be somewhat helped by flattening them out and putting weight on them if you have a few days time to let them settle down, but they don’t tend to completely flatten out, just reduce the amount of cupped shape they have.

Additionally, given the edge leaks the Bel-Arts are known for, I would worry about using the correct size flat filter paper because of the possibility of unfiltered liquid bypassing the filter paper at the edges. Even using a filter aid like bentonite it could still happen because of channeling at the edge.

IMO, for the amount of liquid I had to filter for this batch of winterizing - in excess of 400 gallons at a 10:1 etoh to crude ratio - coffee filters are FAR more economical than dedicated flat filter paper of the same micron size for the larger (16"+) benchtop buchners. Even factoring additional cost of material to make a poly ring. IMO, the increase in flow had by drastically reducing/eliminating the amount of vacuum leaks around the edge makes the oversize coffee filters + poly rings a better choice in the long run because of reduced labor costs and faster turnaround time.

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How well did the bags work out for you? I use a fry oil filter setup for my first room temp pass and it works great there just not very big and have to keep adding to it.

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Those coffee filter are clutch. Did you get the Bel-art filter from us? I always sell the filters with them because they are cheap and holds the liquid instead of letting it flow around the sides.
I also use a 5 gal bucket strainer too and it works really well. I will pre-filter the warm ethanol/crude with the strainer and follow up with the buchner after.
Eventually I am going to redevelop the filter design. Everyone is missing a fundamental flaw with these filtration systems.

@Concentrated_humbold The bag filters that I ordered from Utah Biodiesel did appear to be the same poly material as what my coworker brought in (I later discovered that these different mesh bags were water hash bags). Talked to someone at Utah Biodiesel about buying a bat of that material, they were supposed to email me a quote but never heard back from them. In meantime we got all our material winterized just using the coffee filters. If we have to winterize in the future I will definitely invest in some more of that material, but current plan is moving towards 100% cold extract and hopefully never have to winterize ever again lol. Having varying mesh sizes (especially below 100 micron) would definitely be very helpful but even having 100 micron for first pass would save a lot of time I think.

@goldleaf_scientific the Bel-Art was borrowed from another lab, don’t know who they bought it from. Do you mean that you sell them with coffee filters instead of the flat ones? If so I commend you for doing so, I don’t have a good way to quantify how much but I definitely think that using the flat filters bypasses some nonzero amount of unfiltered liquid around the outside edge.

Would using pool filter sand be a safe, effective option for 1st stage filtering? Never thought of this, but its mainly quartz and silica I believe

Lolz to be honest I use volleyball court sand when I need a hand full. I have not used it yet in my buchner funnel as the filter media per se but use it all the time as layers inside a chromatography column or buchner funnel. The sand keeps the more fragile silica gel layer from being disturbed.

When I run out of alumina I have also used packed silica gel (sand layer on bottom and top) of just a few inches as a filter media only. It is also effective this way though probably filters more compounds than just sand. Each different type of media you pick will choose different components to stick to in addition to the mechanical seperation done by just being sand partical size. Pool sand is GREAT at filtering particulate and has the enormous advantage insofar as things do not stick to it very well. This means that the pool filters can be designed with a back flush mode which effectively cleans the sand filter by backflushing all the gunk out the way it came in so to speak.

Silica gel on the other hand is very sticky to at least some things disolved in solvent. Once the filter becomes clogged then backflushing is not a viable option. The gel itself becomes coated depending on compound. Alumina is much closer to pool sand in the way it behaves but alumina has also been used for a long time in chromatography like silica gel because it too has selective affinity for compounds. However the power of purchased alumina over purchased sand is generally two fold. First of all powdered alumina labelld as 220 grit has been through a series of screens and the partical size is ensured to be unifrom. Uniform particals pack thenselves tighter and more orderly. Second 220 grit alumina is very small. I doubt I could find sand for sale at that size (alumina is usually the “sand” on sand paper).

If all I have is sand and just volleyball court sand then so be it and I work with what is here. As a preference it is alumina for me. I can alter alumina and catch chlorphyll and gunk like that too in a seperate process though it must be done before other solvents have been used in the compound. Plus it is cheap. It comes in both brown and white versions but my supply of the white version no longer has it. Both versions function identically, I just liked the white better for visual reasons.


Thanks for the response brotha! Just got two hochstroms used some old speedibentonite from the brew store today and it worked great. Once that ran out I used some leftover pool sand I had. Crushed through two buckets at 0c in an hour. :smiley:



Mhmm - did you guys think to use your jacketed reactor as your rotovap? We had the same problem you had but we changed up our thinking. There is a much simpler way to winterize which is cost effective and scaleable.

Our problem when I made this post was with scaling up winterization not with solvent recovery, at current time are are able to do 800 lbs/day and should be hitting over a thousand once our BZB falling film shows up.

Though we have gone away from winterization and do cold extraction now I do recognize it would be nice if we were still doing winterization to do the initial ethanol recovery in a different piece of equipment than the rotos, I spent a lot of time scrubbing water solubles and other nasties off of the evaporation flasks on our 50L rotos.

@greenbuggy Scrubbing? Didn’t you just say they were water SOLUBLE?

Scrubbing like scrubbing the dishes, not scrubbing the solute.

@greenbuggy you’re missing my point. If it’s water soluble, use water to just rinse it off. ZERO scrubbing required. Hope that makes life easier for ya.

I was using water after hot ethanol and it definitely didn’t “just rinse off”, took some scrubbing after letting it soak for a while. Don’t know what nasties it carried over but it was adhered pretty good to my glass, glad I’m past that