Define “soak” was there any agitation? What type of system is it?
If there is no agitation - that’s your problem. Also, define “filtered through carbon.” Was that a scrub? Or was it a bed? Column?
Post filtration, did you rinse your cake with clean ETH?
I use a Keg that has the top cut off, I use 5 gallons of -40 ethanol with dry ice. Agitated a lot manually in 75 micron bags for 20 minutes and each micron bag has 5lbs in it. I wash 4 bags totaling 20lbs in the same ethanol, I top the ethanol off with new to maintain the 5 gallon level. Then into a panda. Finally into a pressurized stainless steel column and sent through celite and carbon. after the receiving flask is full. Approximately 2.5 gallons. I change out the celite and carbon for new. Can I just wash it with clean ethanol instead of taking the column apart each time?
Ok. Thats another problem. 5 gallons for 4 bags (20 lbs) is way too little saturation of ETH. At a point, your “tincture” (ETH + extracted Oil) will not strip more oil (or very minimally). I’d suggest using 1 gallon to 1 pound to get full extract.
Personally, I never use columns for scrubs. There are much better ways to strip color and clean oil than using a column in my opinion.
20lbs into 5 gallons is OVER saturating the ethanol. by which I mean there are too many cannabinoids in the solvent to effectively pull more cannabinoids.
That said, one CAN get great extraction at 3lb/gal and even 6lb/gal if you’re spray washing in a centrifuge, so the ethanol has not actually “become saturated”; meaning “it can’t actually hold any more cannabinoids”…
Adding a “virgin solvent” dunk or rinse, so that the solvent left behind doesn’t carry so much of your target with it to the trash is a solid approach.