My name is Erich Berkovitz.

I’ve been processing cannabis for about 10 years. I’ve been living in Oregon and an OMMP patient since 2013. For the last 3 years, I owned and operated PharmEx which was the last operational medical processing site in the OMMP program with the help of Carla Kay (EloquentSolution). Since January 2020 I’ve been exclusively working with hemp and serving on the Oregon Cannabis Commission’s patient access sub-committee. When I’m not in the lab you can find me in cooking (or dabbing) the kitchen or outside in the garden with my beautiful wife and my blue nose pitbull.

What is CRC?

C.R.C stands for Color Remediation Cartridge.  It is an in-line stainless steel column packed with adsorbents such as bentonite clay and silica which your solution passes through and is capable of removing color as well as other contaminants depending on the adsorbents (not aBsorbent) utilized.

 There are many ways to reduce or remove color from plant extracts. One of the most effective and affordable ways to go about that is via adsorbent filtration.  Adsorbents, such as ​Bentonites, are used for decolorizing a variety of vegetable, animal, and mineral oils. They can also be used for clarifying wine, liquor, and beer.

You can apply the methods below to other extraction methods using different solvents, but keep in mind that more non-polar solvents will perform best as most of our filtration media are polar.

Everybody seems to have their preference in filtration media, some people lean pretty heavily on t5, others might use MagSil as their primary adsorbent, and some processors prefer more silica than anything else, while others use a 1:1:1 mix of 3 different adsorbents, etc, etc…. Furthermore, there are over 200 different blends of bentonite clay mined all over the world that all have their own unique properties and can be used in the natural state, activated, or acid-activated.  Below are some of the more commonly used filtration media:

Some media options

Silica  60A (pore size) 200-400 micron (mesh size)  Pulls yellow, orange, and green

B-80 – Crushed bentonite clay – Natural bleaching earth (Much cheaper than t5 and works as well in many applications) Pulls reds, greens, and odor (Carotenoids, chlorophyl,  dyestuffs, peroxides)

Activated bentonite clay / T5 Pulls reds, greens, and odor (Carotenoids, chlorophyl,  dyestuffs, peroxides)

T41/Cbleach  Acid activated bleaching clay with a  pH of 3, contains carbon Pulls odors, color, and some pesticides

Celite 545/ Food grade diatomaceous earth Filter Aid

MagSil- Heat-activated talc  (650F) Pulls lipids

MagSil PR- Heat-activated talc (675F) Pulls water-soluble pesticides

Activated Alumina (aluminum oxide) Pulls reds and yellows

Column supplies  (3”x4”)

3 “ x 3” column

3”x 1” filter plates

3” retention rings x 2

3” high pressure clamp x 3

3” hemispherical cap x 2

Optional T to wet the filter and release pressure

⅜” Valves at top and bottom

How much adsorbent should I use?

This depends on a few things, such as; desired results, size of your batch, and % of starting material, and the oil retention of your filtration media

More is not always better. If you use too much filtration media you can leave cannabinoids behind and risk diminished yields. If you don’t use enough you risk over saturating your media and having impurities pass through that would have normally been removed.

If you’re going to be doing multiple runs on the same CRC you might want to run a larger cartridge with more filtration media or you’ll be changing your filter every 1-2 runs. Running multiple batches through a CRC with insufficient powders can often lead to each pour off being darker than the next. Some people don’t mind half their slabs coming out water-clear and the other half golden, some do. Results also depend on your starting material.

It may take some trial and error to find the exact recipe that works for you. A good way to get started is by calculating your estimated yield and weighing out powders based on that e.g 10lbs of starting material at 10% would yield 454 grams of BHO and from there you can try to make a blend of powders weighing roughly that much.

Packing a column: Example column 3”x4”

From the bottom up

  1. 5 micron filter paper
  2. 25 micron filter paper
  3. Metal ring
  4. ¼” -½” DE / Celite – pressed down
  5. 3” activated bentonite clay – pressed down firmly
  6. ½” silica 60 200-400 mesh
  7. Fill remaining ¼”-½” with DE
  8. Top with 25 micron filter and ring to keep filter media pressed down

Option: Pull vac from bottom while packing

Option: You can press down powders with a shop press and this may help avoid channeling.

Option: Use a paper filter and retention ring as a press to get a nice even surface

Running a column

Fill your material column like normal, and when you’re ready to start pushing through to your collection slowly oven the top of your CRC and allow the CRC to fill with your solution, then open your bottom valve. If you do this too fast or introduce too much pressure at once you can cause channeling which will render your filter useless. At this point you can start slowly adding nitrogen until you see solvent start to come through into your collection. You can use higher pressure to go faster but keep in mind the longer your solution is in contact with the media the more color you will remove.

Pushing with nitrogen

Butane alone will not provide enough pressure to pass your solution through your filter, so nitrogen must be employed. Nitrogen is added to the top of the material column and pressure in the column is brought up to 40-60 psi ( or until solvent starts to enter your collection). Make sure you have PRV’s (pressure relief valves) and gauges on your material column, collection, and recovery.

Disclaimer: If you’re not familiar with using nitrogen with your CLS you need to go do some homework regarding that. Also, check with the manufacturer of your CLS before operating at high pressure.

Drying and heating your clays

It is very important to cook your clays before use to remove any moisture. This will drastically change the efficacity of your adsorbents. You can cook them in an oven above 105c for 1-2 hours, or, (and I haven’t personally tried this) you can microwave your adsorbents for 2-3 minutes twice. Some studies have shown that flash heating your clays will increase bleaching efficiency.

There’s a million ways to skin this cat and this is by no means a definitive guide to CRC

No two filters are alike. Your filter size and media choice are going to depend on your system so this filter is an example and not necessarily a one size fits all. Furthermore this a “poor man’s” filter and there are some great options out there for sintered discs such as n.boler and Quality Stainless Parts. A company called AFS even makes a keurig cup style filter with disposable cartridges that are being sold on BVV. F4200 user J12 puts filtration media at the bottom of his material column instead of a CRC. Not to mention that the list of possible filtration media, zeolites alone, is theoretically endless. And don’t forget and there are other industries that have been using these methods for decades at massive scale.


Wear a mask! Don’t breathe in these powders! Google; Silicosis

Proper filtration needed – you don’t want these powders in your end product!

Use a microscope to check your end product if you’re unsure.

Extra Tip:

Don’t blow your filter up in your face – make sure to release the pressure on your filter before opening it or you will be taking a dust bath that would make an elephant jealous. Open the valves at the top and bottom, and make sure wherever those lines go are also at atmospheric pressure. I usually even pull a slight vac and release on my filter before opening, just in case.

I will be following up with more CRC related contributions in the future. I’ve got some new media to play around with and some more advanced techniques I’d like to share, and we’ll use some of these media with different solvents! But for now, I’m headed to IKEA because my mother-in-law is flying in for a visit and I’ve got to prepare the guest room.

Credits/Shoutouts to: Photon Noir, indofab, waxplug1, Murphy Murri, Carbon Chemistry, Killa12345, n.b.oler, Green Machine,  Dredpirate, Oil-Dri, ColombiaBeneficial, & anyone else I’ve learned from in some way or another.


F4200 thread with 8300 contributions, start digging there’s treasure  

F4200 post from Green Machine Consult with his packing techniques and suggested ratios of media 

How Bleaching Earth Works (Video)

How it’s made and how it works (Video)

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