Distillation is a common purification process based on the difference in boiling points between individual components in a sample. Simply put things that boil at a lower temperature are boiled off while higher boiling point compounds remain. In this case terpenes distill first are condensed and collected. Then cannabinoids distill after and are condensed, collected in a new receiver flask, and what is left is dark tar like plant compounds with the highest boiling points. Because cannabinoids themselves have a high boiling point and would foul or degrade when exposed to high temperatures vacuum is applied to lower the boiling points.
The ideal level of vacuum is one where there are so few molecules in the distillation apparatus that the molecules collide with the apparatus instead of other molecules. This is called molecular flow and occurs anywhere below 50 microns. Only certain models of vacuum pumps can go to this level of vacuum, and usually they will only do so when new, or at least newly rebuilt.
Therefore, it is not advisable to buy used vacuum pumps for this purpose. Used vacuum pumps with less than favorable ultimate vacuum can be either rebuilt or used with a diffusion pump, but a diffusion pump can spew oil and contaminate samples if not used correctly, so only those with experience or training using this type of pump should try. If you wish to rebuild a used pump we have rebuild kits for sale, but we recommend having the manufacturer repair the pump for you.
Please contact us if you wish to have your pump rebuilt. Purification requires the separation of compounds and distillation separates based on boiling points. When you boil something, it will stay at a steady temperature of the lowest boiling point compound no matter how much more heat you put into it until that compound is boiled away. Therefore, when the temperature of the vapor in the distillation head is changing it’s time to collect a new fraction. Again, it’s when the temperature is changing, not when it reaches some specific point.
It also must be noted that in order to make clean solvent free without any issues you must first winterize (dewax) your sample. You will be given the glassware in the kits to make and recover your alcohol in addition to learning how to winterize your sample. There are three ways to perform this distillation each with its own positives and negatives. First is short path distillation set-up which is cheap and effective. It’s cheap in comparison to other options and easy to collect different fractions.
Unfortunately, you can only do one batch at a time and the production capacity is around 1-2 lbs of oil per day. Secondly is the Kugelrohr, which is also a type of short path distillation system. This system is usually a little faster than the standard short path setup but also usually around twice the price. This system also lacks the ability to separate close fractions. Lastly, we have wiped thin film distillation. These are fully continuous machines with the ability to produce more than 2 lbs per hour. They also are extremely expensive at around $100-200k.
You should not expect things to go perfectly the first time. Only outlines of procedures are given and all quantitative information should be treated as estimations. You will have to make your own adjustments and corrections for your particular situation. You may feel overwhelmed or not qualified to perform such operations. This is perfectly understandable, but you will quickly become comfortable with practice because you will realize that it’s actually not all that hard. It’s just distillation, and if hobbyist liquor and spirit makers can do it then so can you.
- Add you sample and magnetic stir bar to the boiling flask.
- Set up your distillation apparatus according to the directions in our kit, or instructions on our site. (Make sure to add a minimal amount of vacuum grease to joints and seal by twisting).
- Attach vacuum tubing to the apparatus to cold trap then from cold trap to vacuum pump.
- Add coolant to insulated container containing cold trap.
- Turn on hot plate stirrer and begin heating the boiling flask.
- Turn on vacuum pump.
- Keep increasing the temperature on the hotplate until the temperature as read from the thermometer in the distillation head stays steady (this indicates a fraction [in this case terpenes] is being vaporized). Make note of this temperature.
- Collect the full fraction by setting the temperature no more than 10° hotter on the hot plate stirrer and continue at this temperature until satisfied that no more is being vaporized.
- Rotate the cow receiver to collect a new fraction.
- Continue to increase heat until the temperature as read on the thermometer in the distillation head stays steady. This indicates a new fraction is being vaporized. Make note of this temperature and set the temperature on the hot plate stirrer slightly higher than it but not too hot or you will have some contaminants like plant pigments vaporize and discolor your final product.
- Continue to collect your desired fraction until satisfied.