Cannabis extractions with alcohol
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During the last years, both extracts made with solvents and solventless concentrates have increased their popularity in an exponential way. This is due, in great measure, to the legalization process that is recently taking place in the USA, also to the creation of Cannabis Social Clubs in Spain.
In this post we present you two extraction methods for those who want to use alcohol as solvent (which will be later purged). We'll see how to use ethanol (which we be the solvent used to illustrate this article) and isopropyl alcohol. Although both techniques have a very similar procedure, there are some differences worth taking into account which will be mentioned at the appropriate moment.
It should also be said that isopropyl alcohol contains more toxic substances than pure ethanol (which actually shouldn’t contain any). Thus, we recommend to use isopropyl exclusively to clean your utensils and glass pipes and not for performing extractions.
Cannabis extractions with alcohol
Known and practiced for many years, this type of extractions are quick and easy to perform. The theory is always the same: soak the plant matter in alcohol to dilute the trichomes in the solvent, i.e. in the alcohol. Once dissolved, we will have to remove the plant matter, filter the solution and purge the alcohol. Let's take a closer look at the process.
Two types of alcohol are mainly used to perform these extractions: isopropyl alcohol or ethanol. We use ethanol because it’s much safer for our health. If we use isopropyl then the process is called “QWISO” (Quick wash isopropyl), while in the case of using ethanol we will talk about “QWET” (Quick wash ethanol). Why a quick wash instead of prolonged soaking? Why we don’t directly heat up the alcohol with the material to extract the greatest possible amount of cannabinoids and terpenes?
The answer is simple: alcohol is a polar solvent. That means that if we use any of these two techniques, we'll also extract other water soluble substances like chlorophyll or alkaloids. In this way, the first requisite is to use plant material as dry as possible. We can dry the material traditionally or in the oven at 90ºC until it crumbles when we press it between our fingers (heating the plant material enables the decarboxylation process of cannabinoids, which lose their acid form and become psychoactive without the need to be vaporized or burned to get you high. This is ideal to develop drugs or cook edibles).
As we oftenly recommend when making extractions, try to use first-class buds or trim and never grind the material prior to the extraction. In this way, the finished product will be much cleaner and therefore of greater quality. Once the material is properly dried, put it inside a storage jar with lid and then into the freezer. We have to do the same with the alcohol that we are going to use. When their temperature is stable around -17ºC, we pour the alcohol in the jar until covering the green material with 2-3 centimeters of alcohol.
Up to this moment, the process to make QWET or QWISO is the same regardless of the chosen alcohol. However, we find now a small variation: in the case of using ethanol (QWET), once the plants material has been covered with alcohol we must stir the mix gently to ensure that everything is well soaked and then put the jar in the freezer again. Wait for about 3 minutes, in which the mix should be stirred gently a couple more times. Then, pass the mixture through a strainer and/or a chinois to seperate the alcohol extract from the plant matter. When using isopropyl alcohol (QWISO), we have to stir the mix of buds and alcohol for 20 seconds and then strain in the same way.
We can keep the plant matter to let it dry and make a second run with alcohol or butane (BHO). Still, and as usual, the quality and yield of this second run will be lower than the first one. It is time now to learn how to separate the solvent from the extraction, either by using bain-marie or heat and vacuum.
Purging the alcohol in cannabis extractions
We now have to filter the solution obtained after using the strainer. To do this, we can use vacuum and laboratory filters (around 40 microns), 25 micron resin drying screens (which is what we used) or simply pour the liquid through a coffee filter. We also used a Pyrex tray to collect the filtered solution; in this way we greatly facilitate the alcohol evaporation process.
Once the first filtering is done (a second filtering may be needed in some cases), place the tray in a water-bath (bain-marie) at about 70-80ºC until no more big bubbles of solvent are created. You can place four small "legs" under the tray so the warm water comes in contact with the greatest possible surface of the base of the container (you can use, for example, four metal caps). Then, filter again with a coffee filter and place the tray back in water-bath. This time, keep the container in bain marie until observing that the formation of small bubbles on the edges of the tray reduces drastically.
If you don’t want the suspended particles to fall into the mixture, simply cover the tray with a 25 micron drying screen or similar. It will catch most of these particles while allowing the alcohol to evaporate.
At this point, and prior to the third and last heating process, we can gather the liquid to filter it into a smaller container for easier handling. Place it again in water bath for a few minutes and your QWET extract is ready!
Vacuum purging of alcohol in cannabis extractions
If we have the equipment needed to vacuum purging our extract (heating plate, vacuum desiccator chamber and vacuum pump) we can use it to removee the alcohol from our extract. The process is very similar to vacuum purging BHO.
After the first water-bath, collect the extraction and place it on a non-stick surface. Adjust the heating plate at 40°C and place the extract in the vacuum chamber. Connect it to the pump, put the chamber on the hot plate and turn the pump on to start the process.
Once the pump starts working, the extract will quickly swell up like a soufflé. At this point, turn off the pump until the sample returns to its normal volume, when we can turn the pump on again. Repeat this process until it doesn’t swell anymore. Then, leave the vacuum working for at least 24 hours (this will depend on how effective has been the first purge with bain-marie, and of course how effective it is our pump).
Always remember to perform all these processes following the corresponding safety measures, and away from flames or heat sources…