Most of the oil that I produce doesn’t get smoked or vaporized, but instead goes into oral or topical meds.
Amongst other differences that makes, is the need to decarboxylate. That means that it has to cook the equivalent of about 120C/248F for an hour to achieve 70% decarboxylation anyway, so I use different utensils and a 250F purge.
I have also developed a process that simplifies clean up and subsequent mixing, so as to not lose excessive amounts of oil to the film left behind in containers.
Material prep varies some, depending on what it is. I usually process prime bud slightly differently, in that I just crumble it up for the first run.
Most of what I run is dry cured leaf material and I start by placing it on a cookie sheet in a 200F oven and cook it long enough that it is just frangible enough to be scrubbed through a pasta strainer to remove the sticks and stems and make it a uniform size. I test for the exact frangibility point by rolling the material between my finger and thumb.
I bought my pasta strainer at a restaurant supply store, and it has a double layer of mesh; one fine, and another coarser one reinforcing it. I wear a leather glove and just scrub it until it passes through the mesh and discard the remaining stems in a separate bag for different processing.
After passing through the strainer, I gallon Ziploc bag or jar the material up until I use it, to keep the moisture content low.
I begin stuffing the column by wadding up a coffee filter and ramming it into place over the injection port. That will diffuse the butane entering the column and prevent plant material from blowing backwards when I remove the butane can with pressure remaining.
I pack the material firmly and evenly, but not tightly, using a wooden dowel at three to four stages on a 36” tube and one on a 12”.
I double a commercial coffee filter and stretch it over the open end and cover that with a patch of 160 thread count bed sheet as a blowout preventer. I hold that in place with a rubber band, or twine, or a screw clamp.
I trim the excess material off after clamping and if I am careful removing the filter assembly after an extraction, I can continue to reuse use it, to minimize oil losses to filter media.
I use a wooden clamp to hold what ever length column I require for the volume I am running. For my own use, I only process once a month and use a 1” X 36” column, which takes three to four 300 ml cans of butane, depending on the material. For smaller runs, I use a 12”, or a 24” column as required.
I have arranged to purchase Lucienne 4X 300 ml cases of butane for around $25 per case and that is primarily what I use.
I use either a lab stand and clamp, or my favorite cat litter bucket stand to support the column as I inject the butane and unlike most instructions on BHO, I usually discharge the butane into a Bain Marie container sitting in hot water, vis a vis a Pyrex pie plate.
I say usually, because I do both, but for oral meds I use the Bain Marie system.
I fill the stainless Bain Marie vessel holding the stainless discharge vessel with hot water from the tap and keep it hot throughout the extraction. That boils the extraction vessel and keeps it full of fumes to float out the high humidity atmosphere that we suffer from in the winter here locally, and stops ice from forming and adding water.
I replace the hot water each time I refill the column and continue to inject into the Bain Marie container until the full extraction is done. When I am through extracting, I continue to replace the hot water until the butane appears to be gone, and then I wipe off the water from the outside of the container, and set it directly in a 250F pot of hot oil.
In my case I use an electric fondue pot full of Canola oil and monitor the temperature with an accurate thermometer. For oral meds, I quit cooking when the mixture in the Bain Marie container stops bubbling and becomes quiescent.
At that point it has not only purged the remaining butane, but decarboxylated the mixture to make it orally active as well.
When bubbling ceases, I wipe the oil off the outside of the container and set the container on the scale to determine total weight. Since I have already weighed the tare of the container, I subtract the tare from the total weight to determine how much oil has been extracted.
Based on that number, and the intended use, I add the remaining ingredients by weight and set the pot back in the hot oil for everything to melt and stir it until well mixed.
Depending on the end use, I either decant it into dropper bottles at this point, or process the oil further as required.