By Troy Ivan
ETHANOL EXTRACTION: COMPLETE BREAKDOWN
The fundamental steps of ethanol extraction are straight forward and quite easy, but for someone looking at it for the first time it can quickly feel overwhelming with the different considerations necessary to achieve various desired end products. It’s really not difficult, but the unfamiliarity can make it feel like rocket science when in reality it’s no more complex than cooking. Once you are familiar with the basics and the unfamiliarity fades you’ll be a pro.
Consider the general steps presented on the left as the fundamental steps to begin with, then moving to the right is the roadmap down the rabbit hole only necessary for those looking to increasingly improve their skills. This is actually the great thing about ethanol extraction, you start with the very basics and easily achieve great results, then if you want to take it even further you can add skills and tools to take it to the next level, and then the next. Don’t worry, I’ll be here with you the whole way!
I’m a little concerned that the amount of information I’m going to present here may add to the feeling of being overwhelmed but I promise you if you just start working with the most basic steps the rest will quickly fall into place and you will not only impress yourself but all of your friends as well. Take it slow, piece by piece, and enjoy your adventure into scents, flavors, and medicinal properties that will blow you away. To help with your learning adventure I’ve prepared a video series addressing the important points of each section. Here’s the introduction video and the rest of the series are presented in each of the following sections.
PREPARE MATERIAL & ETHANOL
Good fortune favors the well prepared as they say and it’s just as important here as anywhere. How the material and ethanol are prepared lays the path for success for the entire extraction process. How the material and ethanol are prepared will be predominantly determined by the desired extraction end product.
Starting material will have a significant impact on the quality of the end product. As a general rule the old adage, “quality-in, quality-out” holds true. High quality material is easier to work with than something like machine trim with substantial structural damage. Beaten up material can still provide great value and potent medicine, it just takes a little attention. Trim, shake, kief and such is pretty much ready to use, but nugs will require some consideration to use as is or break up into smaller pieces.
Use as is or break up
Material with structural damage makes it much easier for the ethanol to pick up the green from the plant and chlorophyll so it can be troublesome. The advantage to material in this form like trim, shake and kief is that it allows the ethanol to move freely across all surfaces and will be very efficient at picking up cannabinoids and terpenes.
On the other hand, intact nugs do a great job at keeping the green out of the extraction but makes picking up all the cannabinoids the nug has to offer more difficult because the ethanol is unable to penetrate to the center of the nug in a timely manner. Even after soaking for 1-hour the inside of a moderately dense nug can remain dry. Breaking up nugs gently by hand, at least in half, while doing the least amount of damage possible, can have a dramatic improvement in yield and no decline in quality. Yield efficiency and quality are always working against each other so achieving the balance that works best for you will take some experimentation.
Ethanol extraction has the great advantage of being able to process the same material more than once. This is important because you can process full nugs for the cleanest extraction and accept the low yield on a first run, then break up the same material and run it a second time more aggressively for a less clean but more efficient yield clean up.
Determining if decarb prior to extraction is necessary is a very important consideration. This topic has been covered extensively in an earlier decarb post, so if you are unclear about all that’s involved in making this decision or how to perform decarb please review here https://extractcrafter.com/2019/01/29/decarboxylation-decarb-101-basic-understanding-and-at-home-method-comparison/.
For a long time people have been under the incorrect impression that ethanol extractions always come out black and heavily laden with plant matter. What temperature is appropriate for any given extraction depends on what outcome and end product is desired. By using temps ranging from room temp to -70°F we have some control over the pickup of waxes, lipids and chlorophyll. Temp is a tool to achieve different outcomes, none are right or wrong, just different.
Room temp ethanol is the warmest that should be used for extraction. It will be very aggressive and grab everything it can making it highly efficient in the collection of cannabinoids as well as deeper plant components. NEVER use “butter makers” or other contraptions that add heat and/or chop material to prepare a wash or tincture, it’s the absolute worst possible approach.
Room temp extractions will be deep green to black in color with a very strong green plant aroma and flavor. This is often referred to as Rick Simpson oil (RSO) or Full Extract Cannabis Oil (FECO). These extracts are great for many things, but for smoking and vaping a cleaner extraction is necessary and can be accomplished by processing at lower temps.
Freezer, Medical Freezer, Dry ice
Cold temps make ethanol less aggressive but more focused on picking up desirable cannabinoids and terpenes, leaving the green matter and undesirables behind. The use of low temps is essential to making clean golden extracts, especially for vaping. A regular freezer, medical freezer, or dry ice can be used for low temp processing.
When using a regular freezer, have the cannabis and ethanol stored separately in the freezer for at least 24-hours. Medical freezers and dry ice can get the material and ethanol down to temp in a few hours. A very nice concentrate can be made using a regular freezer so don’t feel like buying an extra freezer or dry ice is a requirement for quality products, it’s not. Like any hobby or craft there are higher levels of process application that aren’t required but can be pursued if you choose; that’s where the dry ice, medical freezers and very cold temps between -40°F and -70°F come in.
COMBINE FOR WASH
Ethanol and cannabis are combined to allow the ethanol, working as a solvent, to collect the desired components from the plant into what we call the “wash.” The wash is actually the same thing as a traditional “tincture” so you may hear it called that as well. How we go about combining the ethanol and cannabis for the wash is what’s going to determine which components from the cannabis will be included in the final product. To exercise some control over the final outcome we have temp, time, and agitation to work with. The wash processing temp was decided in the previous “preparing material & ethanol” step, so now we concentrate on time and agitation.
(Again, NEVER use butter makers, infusers or any contraptions that are adding heat, chopping and over complicating this step.)
This is perhaps the most difficult and frustrating part of the entire process because there is no steadfast rule, only estimation and observation. This is where the art of extraction meets the science. The amount of time the ethanol and cannabis are combined for will allow or restrict the ethanol from performing its solvent duties. If it soaks too long it can become green and if the soak is too short yield will suffer. For making RSO/FECO the exposure will be longer and for vaping oil shorter depending on the material and temps. It can be difficult and frustrating because every extraction will be different when the material or temperatures are changed and it’s not reliably predictable without building an experience base.
We know that damaged material will leak green plant matter more easily than material that’s mostly intact. It should then be obvious that to avoid picking up green, the damaged material would have a much shorter soak than intact material for comparable results.
Expertise in managing the time and temp balance comes quickly with just a little experience. It’s very hard to put a finger on it in words, but once you work with it just a few times it will be clear.
At room temperature, popular for making RSO/FECO type concentrates, the ethanol will pull green almost immediately regardless of the condition of the material. Even for a relatively short wash time, a lot of chlorophyll, wax, and lipids will collect in a room temp wash. You will undoubtedly hear “I’ve been doing this for 30-years” old-schoolers telling people they need to soak for days, weeks or even months but I would strongly disagree. Ten minutes is plenty, 1-hour is more than enough and 24-hours is substantial overkill but some people may want to do it anyway. Anything longer is not necessary.
Cold temps appear to slow ethanol’s cannabinoid pick up efficiency considerably. There is a noticeable reduction in undesirable pickup up and yield efficiency as temps get lower and lower. This is why the exposure time for the wash in a freezer will be different than dry ice or a medical freezer. The freezer extraction, while very clean, will not be as clean as the colder temps, and the colder temps will have considerably lower clean yield for the same duration of exposure.
A typical wash exposure time for working with freezer temps (0°F to -5°F) can range from 1-minute to 24-hours. The shortest exposure is for a clean extraction with very damaged material and the longest for making a cleaner version of RSO/FECO with everything in-between is a sliding scale depending on the material and desired extraction outcome. A good exposure range for a clean vapable concentrate using good material is 5-20 minutes.
For the dry ice and medical freezer temps (-40°F to -70°F) the exposure time elongates significantly from as short as 20-min out to 24-hours. This range has been stretched out to as far as a week at the coldest temps, but from what I have found it’s not necessary to stretch that far. My rudimentary experiments (in no way absolute nor definitive) I’ve seen yields top out after about an hour or two.
Agitation is the act of gently shaking the container periodically during the wash process. This helps to move the ethanol around, causing disruption to trichome stability, getting the solvent to thoroughly cover all surfaces and minimize any points of saturation layers.
Agitation helps with the efficiency of pickup, meaning that by actively moving the ethanol around and through the plant material it aids the ethanol in picking up more of the oil the plant has to offer. Working with colder temps makes agitation more important because of the slower efficiency we experience as temps get lower. The combination of low temps and no agitation will lead to surprisingly low yields.
Can cause green
The image of damaged, ripped, and torn edges of plant material should make it pretty easy to visualize how easily ethanol can come into direct contact with the green matter inside the plant material and collect it. With that in mind, it’s quite obvious that in addition to increasing the cannabinoid collection efficiency, agitation will also quickly increase how much green the ethanol picks up. If you don’t mind the green in your extraction then you can shake it up as much as you like. On the other hand, if you are shooting for a clean extract you have to be more careful, only increasing the intensity of agitation when the material is more intact and as temps get lower. Even heavier agitation with good intact material won’t affect quality, but the more damaged the material is the higher the chance of green leak.
STRAIN & FILTER
Once the wash is complete, the next step is to isolate it from the plant material for further processing by first straining, then filtering. Straining is straight forward, but filtering may be as simple as a couple coffee filters or beginning down the rabbit hole with slightly more complicated, finer filtration equipment depending on the desired end product, required quality, time value and budget.
Removing the larger plant material quickly serves two purposes; it gets the material away from the ethanol quickly to arrest the risk of picking up green and removes material that will quickly clog filters in the next step. When making deeper RSO/FECO extracts, separating the plant material expediently is probably not a priority, but when making the cleanest possible extract with cold temps it’s helpful to separate the plant material away before it begins to warm.
A simple metal mesh kitchen strainer works perfectly, allowing the ethanol to flow very quickly and uninhibitedly away from the material. Set the strainer atop a collection bowl and pour the contents into the strainer catching the roughly strained wash in the bowl. The roughly strained wash isn’t quite clean enough to be processed yet, having small plant material particles in the wash will act as sediment during processing and cause splattering.
Nylon mesh material is very handy but not as easy to buy or inexpensive as a kitchen strainer. This is just an option to make processing easier down the road, it’s not a necessary piece of equipment. It comes in a large swath down to about 40-micron and can be cut into appropriately sized sections. The 40-micron size works well because the flow is still fast with the large surface area and it catches a lot of the smaller particles. Mesh brewing or nut bags are similar, but they have sewn-in corners and seams that I find more difficult to manage, whereas the sheet-material shape can be manipulated as necessary in process and can then be laid flat for easy cleaning, drying and reuse.
To use I lay the mesh material over a large strainer set atop a bowl, apply clips to hold it in place, then pour the soaking material and wash into the mesh, catching the well strained wash in the bowl. It’s better than just a normal strainer alone and will make filtration easier, but it’s not important enough to worry about and rush out to buy.
After straining there will still be small, fine particles remaining in the solution that can be cleaned up with filtration. The fine particles can be difficult to see in the larger liquid volume of the wash but once the ethanol begins to decrease in volume those same particles become a larger and larger component as the extraction reduces to a concentrate. How much that matters depends on what’s being made and the quality required. For some applications a single pass through a coffee filter may be sufficient, for others finer filtration with the Buchner may be necessary, or some may even go to the extra lengths of winterization.
Unbleached coffee filters are the easiest and most accessible form of filtration. A typical coffee filter is about 20 microns which is sufficient for edibles and topicals but not adequate for the best quality clean extracts. Two coffee filters can be stacked to provide a little better filtration than a single layer. The main disadvantage to using coffee filters is that it takes quite a long time for the wash, pulled only by gravity, to flow through them. Trying filtration with coffee filters before moving into a Buchner funnel set is a good idea because it may well suit your needs and save some cash. Once the wash has been satisfactorily filtered it can either be run through the machine or cleaned up further with winterization.
The Buchner funnel set has three main components: funnel, flask, and filter paper. The Buchner funnel is also available with a fixed glass frit instead of the paper filters but I wouldn’t recommend that for this level and application because they clog quickly and are very difficult (impossible) to clean. Buchner funnel filtration provides a few advantages over coffee filters. First, it’s a big time saver. The vacuum assisted flask pulls wash through the funnel and filter paper much faster than gravity pulls it through a coffee filter. Second, there’s a wide variety of filter paper grades and speeds to choose from providing great versatility and control. Fast flow filter papers are about 20 micron, medium 12 micron, and slow 3 micron. Third, great filtration creates the highest quality concentrates. Once the wash has been satisfactorily filtered it can either be run through the machine or cleaned up further with winterization.
Here is a good video explaining all you need to know about Buchner filtration https://www.youtube.com/watch?v=LMSpOBjiY-M&t=15s
During the wash process ethanol can pick up lipids and waxes that may or may not be desirable. Some botanicals have more lipids and waxes than others, so knowing the characteristics of the botanical being used and planning for the desired end product will determine if winterization is necessary. For topicals, the lipids and waxes may add a benefit to the final formulation. For edibles, going through the extra step of removing lipids and waxes isn’t necessary unless you are looking to cook with the cleanest extraction possible. However, for extractions to be vaped, eliminating lipids and waxes is important for potency, taste, smoothness, and ease on the lungs.
Winterization is a process of subjecting the filtered wash to freezing temps for a period while the lipids and waxes fall out of solution and coagulate into a gelatinous form that can be filtered away leaving an incredibly cleaner wash. To do this, the wash can either be placed in a freezer for 48-hours or on dry ice for 3-5 hours, then run through coffee filters or a Buchner with a medium flow filter or two fast flow filters so it goes faster than a slow filter would and you don’t have to worry about temps warming.
If the wash was effectively processed with cold temps it’s possible that wax and lipid pick up was already avoided and would make winterization unnecessary. When I work with cold temps I generally skip winterization but it’s a tool I often go back to when I want to make sure I have the cleanest possible extract.
Now the wash is definitely ready for processing………unless you want to scrub.
Scrubbing is an advanced technique for lightening color and removing undesirables from an extraction intended for vaping. This step is quite a ways down the rabbit hole and absolutely not necessary for 95% of at home extraction applications. This isn’t out of the reach of normal people to execute and can be fun to experiment with but it’s an advanced process that isn’t necessary to make high-quality extractions, it just takes it to the next level. The big boys work with “Color Remediation Columns” (CRC) which is beyond our scope but it’s nearly the same as us scrubbing with activated carbon (AC), diatomaceous earth (DE), and other filtration media that’s available. For more information see the link provided at the end of this post.
We’ve crafted a spectacular wash and the real “extraction” phase is over. Now, to get to the cannabis oil that’s been collected by the ethanol we have to evaporate the ethanol, separating the oil and ethanol that constitutes the wash. Ethanol evaporates at lower temps than most of the other cannabis components which is what allows this process to work. As the ethanol evaporates the cannabis oil will become more and more concentrated, like a culinary reduction, and hence become a “cannabis concentrate.”
At this stage, in the not so distant past, we would’ve been talking about old-school rudimentary, unsophisticated applications like allowing the ethanol to naturally evaporate into the air or using ad hoc tools like rice cookers or water distillers. These traditional techniques will allow for some degree of success in making only heavily oxidized and overly decarbed oil, but fortunately we now have the ability to more closely simulate lab processes and higher quality results by working with vacuum and low temps at home with easy to use tools like presented in the DIY Vacuum Still blog post and video:
Video running the DIY Vacuum Still
DIY Vacuum Still (Part 1): Components and Process
DIY Vacuum Still (Part 2): Putting Together and Operation
Ethanol recovery, under vacuum, at low heat, with a fast production rate and nearly perfect recovery efficiency, while keeping the oil under control is by far the most technical part of the entire ethanol extraction process. Don’t be intimidated, it’s not that hard, especially if you follow my DIY guidance.
(Considering the current state of ExtractCraft I can no longer recommend the equipment. I have serious concerns about the quality of equipment they are producing and the longevity of the company which makes how long they will be able to properly support the equipment they sell and provide quality customer service uncertain.)
In this section we are going to look at what’s happening in the equipment that allows it to concentrate the oil and recover the ethanol. Then, we’ll take a look at when to stop the process. It’s really easy when you know what you’re looking for.
CONCENTRATE – Reduce to concentrate
After loading the wash and starting the machine, the vacuum pumps reduce the pressure atmosphere inside the unit to a point where the ethanol is able to evaporate at around 100°F. As the ethanol is evaporated and separated during the process the wash will become a more and more concentrated tincture, eventually turning into a very potent oil consistency.
*Processing Note: People often want to stop the run part way through, add more wash, then restart the machine. This is not recommended as it provides no advantage, will cause bumping which makes a mess and will lower the quality of the first run by (re)processing it much longer than necessary. Run one load at a time, start to finish: concentrate, recover ethanol, and stop.
RECOVERY – Ethanol recovered
As the process evaporates ethanol away from the wash it is condensed and recovered away from where the wash continues to concentrate. The high efficiency of containing the evaporated vapor, condensing, and collecting the reclaimed ethanol serves two very important purposes. First, it contributes substantially to the safety of the process by stopping flammable vapor from filling the surrounding area. Second, the ethanol can be reused for more extractions providing real sustainability and economic impacts. The machines actually pay you back every time you use them.
Even though the machines give back essentially all of the ethanol for reuse there are a few considerations that need to be understood. Ethanol can be evaporated and condensed over and over with no problem but it’s important to make sure water isn’t picked up along the way in processing or when using equipment that may have residual water from cleaning. With reasonable caution in processing picking up moisture shouldn’t be a problem. Additionally, there’s a natural ethanol restocking cycle built into the ethanol extraction process that protects your production flow. Even with the machines returning almost all the ethanol loaded into them, the plant material used to make the wash will not. Plant material can hold onto 15%-30% of the ethanol used when making the wash depending on how aggressively you attempt to recover it. Lastly, the recovered ethanol will be crystal clear and appear “pure” but you’ll find that some of the lighter volatiles from the extraction will travel with the ethanol as it evaporates and is collected. There may be a slight fragrance in the reclaim which is no problem for reusing as it’s quite minor and will most likely travel again when used. That said, some may want to keep the reclaimed ethanol of one type of botanical extraction separate from another, especially in an extreme cases of strong botanicals like hot chili extractions.
STOPPING – Stop when ready
First time users often fret unnecessarily about when to stop the process. Not having an exact shut-off time is another example of how science is intertwined with the art of extraction. The timing of when to stop the process and collect the oil is subjective, based on intended use and personal preference. The process can be stopped early when there’s still a good amount of ethanol remaining for a very concentrated tincture, or, let it go longer to become an oil. I typically target a very light cooking oil consistency. The consistency can be observed in process by tilting the machines gently to see how the liquid moves and decide when it’s ready. Some stop when it’s more liquid so it pours out more easily and others may let it go longer so the oil becomes stable more quickly, it’s all up to the crafter’s preference.
The EtOH PRO and Source Turbo have significant problems at the end of process. The EtOH PRO has a prolonged stall that makes getting all the way to oil difficult. Contrarily, the Source Turbo has a significant temperature overshoot if run slightly long that can exceed 160°F up to 180°F. The DIY system provides very close control of exactly how you want to finish the oil.
COLLECT & FINISH OIL
If I’m purposefully making a very liquid-like, high alcohol cannabis concentrate tincture it will go from the crucible into a glass bottle. Otherwise, when I’m ready to collect the oil I put it straight onto a silicone mat regardless of how thick or thin it is using a mini-silicone spatula to help collect the goods from the crucible while it’s still warm. When the oil is so thin it will flow off the mat, I make a boat out of a silicone mat by pinching each corner with a binder clip. Once on the mat I typically let it cool and plan for what I’m going to do with it next.
*Processing note: use the unprinted side of any logo’d silicone mats. The printing will eventually begin peeling so to keep it out of your concentrate just use plain side.
The oil produced by the end of the process is the foundation of most concentrates and able to be used in many ways. It can be used as is, decarbed, or post processed to increase stability if desired. What you do with the oil after removing from the machines depends mostly on the ultimate intended use of the concentrate.
Please know the knee jerk reaction/question, “How do I get ALL the alcohol out?” is fundamentally flawed because there will always be some residual ethanol remaining even if only measured in “parts-per-million” (ppm), and that’s ok. The idea of residual ethanol causes some people concern and they jump to the conclusion that any remnant of ethanol is bad. I assure you, if it were known to be bad I wouldn’t be using it, writing about it, or recommending it. To keep it in perspective think about what we are working with; food-grade ethanol (alcohol), that has no known adverse health effects when consumed orally or vaped in minuscule amounts. It’s also useful to remember that a bottle of vanilla extract used for cooking is typically 35% alcohol by volume and no one worries about that, right? So, the question isn’t automatically, “How do I get ALL the ethanol out?” The question should be, “How much residual food-grade ethanol is acceptable for me and my application?” That question will determine if you use the oil as is or to what degree post processing is necessary.
USE AS IS – Edibles, tinctures, topicals
When the process is stopped determines how much ethanol is present in the concentrate at that point. If the process is stopped very early and it’s still water-like, the alcohol component will be quite high and similar to the vanilla extract used for cooking mentioned earlier. This is what I would call a “tincture concentrate” and can be used for cooking or incorporated into other formulations. If consumed orally on its own, the large ethanol component will have a significant flavor and burn in the mouth.
When the process is stopped at an oil consistency, it’s probably between 3%-5% (30,000-50,000 ppm) residual ethanol. This sounds high but it’s not something to automatically worry about for many applications. The ethanol is food-grade and meant for human consumption, it will continue to evaporate when exposed to air, and will become much more diluted when incorporated into a larger formulation. The applications for using this as is would be for tincture concentrates, edibles, and topicals. Contrarily for vaping concentrates, even though I don’t know of any documented adverse health effects from vaping ethanol, post processing to reduce residual ethanol to a much lower level is necessary.
If the desired final product requires decarb, decarbing the oil now can be a great alternative to decarbing the plant material in the beginning. Decarbing the post-extraction oil has a few advantages. First, it provides flexibility in processing; half of the oil can be decarbed and the other half left un-decarbed for separate uses or combined together again to maximize medical benefits of THC-A and THC together. Second, the temps involved in decarbing oil will ensure the residual ethanol will be effectively evaporated off for those concerned. Third, the decarbing process is observable and gives nearly perfect visual feedback to show when the oil is finished decarbing. Lastly, while still pungent I don’t think the smell is as strong as decarbing the plant material.
The chemical action breaking off a carboxyl group and reducing the molecular size of THC-A to THC is the same for decarbing flower or oil. What that means in general is all that’s necessary to accomplish accelerated decarb is heat from a given heat source. It’s possible to use a regular oven, toaster oven, or about anything that provides heat to achieve the desired decarbing outcome, however, if the concentrate has not already been purged well residual ethanol vapor released during the process can create a serious fire hazard. Closed environments, especially with possible exposure to an ignitions source should be avoided when decarbing concentrates that aren’t already well purged. I would recommend either a hot plate or a heated magnetic stir for the home user to allow for vapor to be properly vented and provide visual access to observation during the process.
Decarbing with a hot plate is easy access and inexpensive for beginners to try and it’s the way I first started working with decarbing oil. Make sure the container chosen is made for direct heat applications, has a flat bottom to evenly transfer heat and enough room to allow for the expansion of the bubbles created by decarb. Lastly, make sure to continually stir during the process for even heat distribution. The main difficulty with using a hot plate is controlling the heat to some extent, especially with the cheaper ones. The reality is we aren’t working to lab standards and decarbing is actually much more forgiving than it’s often portrayed to be, so if you choose to use this option pay attention to temp but don’t stress over it too much. To control the heat you will need an instant read thermometer to keep the heat between around 240°F – 260°F and a heat resistant glove to pick up the hot container when necessary. The hot plate temp won’t change quickly when adjusted so to regulate manually pick it up off the hot plate while stirring to stop heat from building and set it back down to resume heating. It’s really ad hoc manual heat management but it works on a budget. As the heat builds the tiny decarb bubbles begin to form, increase in volume, taper off and finally stop. Once the bubble completely stop then decarb is complete. No it’s not perfect and far from lab standards but it’s safe, works great, and inexpensive compared to the alternatives.
A magnetic stir is the perfect equipment for decarbing oil and makes life very easy but comes with a pretty hefty price tag. The process, temps, and vessel considerations are the same as with the hot plate but with a hands-free approach. If decarbing oil regularly, especially in moderate to larger volumes, a good magnetic stir is definitely worth the investment. I would recommend a unit that accommodates adding a thermocouple to manage the heat so all you have to do is get it started, observe and enjoy the show.
When the oil straight out of the machine is not suitable, and decarbing the oil is not necessary, post processing will be in order to increase stability by reducing residual ethanol. Post processing is referred to as “purging” because the ethanol is being further purged from the concentrate. Deeper purging is necessary for making concentrate forms for vaping like wax, crumble, pull-n-snap, shatter, sauce and vape cartridges. There are many methods used in post processing: air drying, heat pads, vacuum chambers, and vacuum ovens.
Air drying is the most easy and basic post processing approach achieved by spreading the oil in a thin layer on a silicone mat and allowing the ethanol to naturally evaporate as the oil cures and becomes more stable. Once it’s mostly stable the concentrate can be moved to parchment paper if desired. This process can take anywhere from 1-day to 1-week depending on ambient environment, strain characteristics, and how much residual ethanol was in the concentrate when poured onto the mat. Under optimal conditions I’ve seen air cured extractions test down to around 2,000 ppm after a couple/few days.
To speed up the natural process of air drying, oil on an appropriate silicone mat can be placed on a very low-heat heating pad like a coffee warmer or reptile warming pad. The added heat in open air can lower the concentrate quality a little, so it may take some experimentation to see if the outcome is acceptable for your needs.
Taking it to the next level by purging deeper and faster, a vacuum chamber kit or vacuum oven can be used. This equipment adds vacuum to the post processing which allows ethanol to degas from a concentrate much faster and efficiently than in ambient atmosphere. Working at this level opens the door to increased stability and concentrate forms.
I always recommend that people start off with air drying and move into more equipment later after they get a feel for the natural purging process. This serves two purposes: it creates experience and knowledge of the base process and it may save money if it’s determined that natural air purging is sufficient. Later, if you want to venture down the rabbit hole and work with the advanced equipment you’ll be ready. Fortunately, if you are working with the DIY vacuum still for ethanol recovery the components you need for post processing are also included in the system!
Down The Rabbit Hole
There are even deeper paths down the rabbit hole with crashing cannabinoids to make sauce, using starches like cyclodextrin for powdered form cannabis oil, ultrasonics for nano-emulsification and short-path distillation to make distillate. These processes take a bit more knowledge, experience, time, and sometimes costly additional equipment. The bad news is, it’s so much fun you will have a very hard time resisting being pulled further and further in.
Notes on post processing
Finally, there are a few things to keep in mind with post processing. Some materials and strains won’t become stable no matter what you do. Very terpene rich material and some strains tend to make concentrates crash and sugar instead of becoming stable. Also, material that is old and extractions that were not well filtered, decarbed, or contain undesirable components like fats and waxes will resist stability. Often, when people are chasing stability they lose focus of important things like terpenes and concentrate character and over-process their concentrates. Lastly, if very accurate residual ethanol and potency measures are necessary the only way to know the real numbers is by having samples tested by an accredited lab, anything else is just guessing.
MORE READING AND INFORMATION
I hope this has been informative and I hope you give ethanol extraction a try, you’ll have much fun bringing to life creations you never thought possible. For more information on specific topics there are a number of links provided below.
STAY LIFTED AND ENJOY!!!!
Decarboxylation considerations and methods: https://extractcrafter.com/2019/01/29/decarboxylation-decarb-101-basic-understanding-and-at-home-method-comparison/
Using dry ice for cleaner extractions: https://extractcrafter.com/2016/07/27/super-cooled-qwet-wash-for-cannabis-extraction-using-dry-ice/
Comparison of freezer temps and dry ice for extraction: https://extractcrafter.com/2017/06/28/cannabis-oil-qwet-extraction-battle-of-the-wash-dry-ice-vs-freezer/
Yield considerations when making the wash and concentrates: https://extractcrafter.com/2020/04/05/extraction-and-yield-its-a-balance/
Scrubbing and polishing extracts: https://extractcrafter.com/2018/09/22/polishing-dark-extracts-carbon-scrubbing-diatomaceous-earth-de-filtering/
Winterization explanation and process: https://extractcrafter.com/2017/12/04/winterizing-polishing-extracts-using-ethanol/
Cooking with, handling, estimating potency, calculating potency: https://extractcrafter.com/2020/04/18/cooking-with-cannabis-concentrates/
Making RSO and FECO: https://extractcrafter.com/2016/06/04/rso-feco-using-the-source-home-healing/