6" CRC soak issues

Hey guys,

Running into an issue where my 6" crc wont soak all the way through. It tends to use the top few inches of powders then it seems to channel through the rest of it.

First try i filled it quickly as i would with the 4". I ended up with a softball sized ball of hard powders underneath the top layer of used powders, and it obviously channeled down the sides of the spool.

Second try filling it slowly I got the top few inches to be used then the rest of it looked unused except for maybe some channeling straight through. (green specs here and there)

I was able to get a full soak (looking at the powder color) by hitting the 4" CRC with a rubber mallet.


Warm tane
1/2 inch valves
3/8 lines

CRC from Killa12345
Filter paper against the 5 micron disc
T5 against that
B80 on top

packing under vac with a vibrator and hitting it to settle.

2 lines feeding directly to CRC from columns and one going to the collection.

I have a pressure gauge on the bottom of the CRC to monitor pressure under the filter bed.

As far as SOP for the filter I have been cracking the top of the CRC and slowly filling it around 50PSI… I let a tiny bit of fluid out to the collection (drips) as the CRC fills then i close it off when i see a steady drip and no air bubbles coming out. Giving it about 20-30 minutes on the first run to get a good soak of the powders but no luck!

Thanks guys!

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Have your tried wetting your clays with just pure solvent first or Silica 60?

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Havent tried just solvent yet (on a first run)

Ill give that a shot.

Trying not to use silica, been getting good results without it

Have you tried going into a 3in? I’ve seen channeling as well in a 3in but not as bad…seems like 1.5 or 2in is the best bet to ensure all the powders are spent from the diameter of the channel I saw


Soak the powder initially with fresh butane. Begin the introduction slowly to break the vacuum and not blast powder everywhere. Soak it all the way through as much as can pull in, then open the flow to your collection and let that lower pressure pull a good amount of liquid through.
You do pull vacuum from the bottom to pack the powder into the column correct? Very important to make a real solid cake.
After your actual solution flows through run more fresh butane over to wash out the oil left in the powders. Once you recover that all the way down and open the column up the cake will have shrank and you’ll probably see some cracks in there, it doesn’t matter as long as your solution came out clear, the channels are only from the cake drying out



Yeah im packing really well under vac.

So i should run fresh solvent through then recover it from the CRC then start or leave the CRC full of fluid then start the run?

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You don’t want your powder to completely dry until the very very end. Most of the time in column chromatography you want your powders to remain fully saturated the entire time. Unfortunately for us the flow rates are relatively quite slow and it gets through that media. Don’t worry about that, but when the flow does slow way down remember it will dry out if you keep pulling. N2 pushing works better than pump pulling so I aim to get most of the solution through before turning on recovery pump

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leave it kinda full id say without too much pressure that you can fill it with out back pressure being an issue

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sounds like you got the idea correct man. i personally have waited 30 minutes depending on the media to saturate. doing a solvent wash and not recovering letting it be wet i think works wonders


I’ve not really come across any channeling issues since I’ve been pulling vac on the CRC for a good 30 minutes before starting the run. Also definitely rinse with clean solvent prior to starting the run, and leave enough solvent in the CRC so that it is wet/primed before you run the solution through it.


That seems like a time consuming unnecessary step…

Thank you so much guys :slight_smile: :sunglasses:

Well your kinda wrong. It for sure helps

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Do u ever use a sight glass to monitor channeling etc real-time?