My plan all along was to make high CBD, low THC RSO (Rick Simpson Oil) for my wife who has Parkinson's, but I was irked at the idea of letting a couple of liters of 190 proof grain alcohol just evaporate away. So, I built this admittedly crude apparatus. Basically it's a still, but the it has two end products, The re-condensed alcohol and the residual RSO in the boiling flask.
A glass 1 liter 'boiling flask' sets on a steaming rack inside an electric rice cooker in a water bath that comes up about to the level of the cannabis tincture in the flask, or a little higher. The 1/2" OD copper tubing is attached to the flask's 1.5" neck via a #22 cork with a 1/2" hole drilled through it. The pipe insulation on the uphill portion of the tubing helps to minimize the amount of alcohol vapor that condenses where it will just drip back into the flask. The tubing is coiled inside a 5 gallon bucket filled with ice, and exits at the bottom where the alcohol drips into a recycled tequila bottle.
It's important that every part of the tubing past the high point is sloped downward so that none of the condensate can 'pool' up in a low spot, and thus inhibit the flow of vapor out of the flask. Before I began processing cannabis tincture, did a 'dry run' with just alcohol to make sure it was working properly.
As the level of the tincture in the flask gets lower, the process becomes less efficient, because there is less area of the tincture in contact with the glass, so less heat is transferred to boil off the alcohol. I started with the flask about 3/4 full, then paused the process when it was about 1/3 full and added more tincture, repeating until there was none left. Then continued to cook it down until there were only a couple of ounces (~60 ml) left. At that point, it was barely bubbling, so I poured the remainder into a 2 oz. shot glass while still warm, and let any remaining alcohol evaporate naturally. A little oil wound up on the inside surface of the flask. I just left it there where it will be joined by the extraction from the next crop.
I recovered about 6 cups of pure clear alcohol, which tested at 190 proof. Same proof as what I started with, but did lose some volume.
Click on the thumbnail to watch short movie of the process in action. The small measuring cup next to the alcohol receiving bottle is just catching the ice melt that leaks out around where the copper tubing exits the bucket, to keep the area a little bit tidier. I'll address that 'cosmetic' issue in Rev 2.
A glass 1 liter 'boiling flask' sets on a steaming rack inside an electric rice cooker in a water bath that comes up about to the level of the cannabis tincture in the flask, or a little higher. The 1/2" OD copper tubing is attached to the flask's 1.5" neck via a #22 cork with a 1/2" hole drilled through it. The pipe insulation on the uphill portion of the tubing helps to minimize the amount of alcohol vapor that condenses where it will just drip back into the flask. The tubing is coiled inside a 5 gallon bucket filled with ice, and exits at the bottom where the alcohol drips into a recycled tequila bottle.
It's important that every part of the tubing past the high point is sloped downward so that none of the condensate can 'pool' up in a low spot, and thus inhibit the flow of vapor out of the flask. Before I began processing cannabis tincture, did a 'dry run' with just alcohol to make sure it was working properly.
As the level of the tincture in the flask gets lower, the process becomes less efficient, because there is less area of the tincture in contact with the glass, so less heat is transferred to boil off the alcohol. I started with the flask about 3/4 full, then paused the process when it was about 1/3 full and added more tincture, repeating until there was none left. Then continued to cook it down until there were only a couple of ounces (~60 ml) left. At that point, it was barely bubbling, so I poured the remainder into a 2 oz. shot glass while still warm, and let any remaining alcohol evaporate naturally. A little oil wound up on the inside surface of the flask. I just left it there where it will be joined by the extraction from the next crop.
I recovered about 6 cups of pure clear alcohol, which tested at 190 proof. Same proof as what I started with, but did lose some volume.
Click on the thumbnail to watch short movie of the process in action. The small measuring cup next to the alcohol receiving bottle is just catching the ice melt that leaks out around where the copper tubing exits the bucket, to keep the area a little bit tidier. I'll address that 'cosmetic' issue in Rev 2.
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