SPD First Pass: Common Fractions

First Pass

Head Vapor Temperatures:

  • Volatiles /Terps 65-100C (80-140C mantle temp)
  • Head Fraction 101 – 155C (140 – 185 mantle temp)
  • Main Body 158 – 180C (195-205 mantle temp)

Light Volatiles / Residual Solvents

Usually we will start our deep-vacuum distillation with the boiling flask contents at an approximate temp of 65-100C. This is the typical temperature at which you can easily transfer the crude material from one vessel to another at a reasonably low rate of transfer loss. At this temperature, you can assume that there may still be a small concentration of solvent and volatiles. If you are coming from a winterization / rotovap pre-process, alcohol/water azeotropes will be the most prevalent fractions coming out at this temperature as well as some light terpenes. If you have not previously activated or decarboxylated your crude – you will have a fair bit of activity in the flask as the Acid groups (the A in THCa) start to detach from the THC molecule and leave the system as carbon dioxide. It’s important to have your head and subsequent condensers set to the coldest possible temp during this process to avoid soaking your pump and cold trap with volatiles (which will affect your vacuum performance later if done improperly). We recommend a pre-distillation “punch-out” on a hot plate or in your Rotovap prior to transferring your crude to the SPD for initial distillation. This will preemptively safeguard you from having to deal with these vapors in your short path system. There are multiple methods to do this punch-out (sometimes called a degas/devol/decarb), you can learn about that in the next article.

Stirbar speeds should be ramped up to ¾ of the bar’s maximum potential as quickly as possible without knocking the bar out of position. (More on stir-bars here)

Step up by 10 degrees on the mantle as your ramp up your boiling flask temperature at this stage.

Light Terpenes

Once you have transitioned beyond this step, you will notice a clear fraction of terpenes and other aromatics condensing in the head. Your boiling flask temperature will be around 100-140C with vapor temperatures spiking upwards of 110C. You should keep a low temperature on the condensers and keep an eye out on your vacuum depth.

Chlorophyll, Esters, and heavy Terpenes

Boiling flask 140-175C will yield some interesting fractions – these will vary depending on the type of crude you are working with and the temperature of the solvent during primary extraction (IE BHO vs. Etoh vs. Co2). Typically, we will start warming up the condenser temps gradually to avoid a clog in the pathway – these compounds are not as volatile and require a bit more heat to slide out of the head. 35C is a good number to set your chilling/heating unit to this stage. You will notice a menagerie of colors including reds, yellows, and eventually greens. Azulene blue may also show-up at the peak of this temp range if your vacuum levels are deep enough.

Cannabinoid Imposters

Once you achieve 175C on the mantle and you still have not “popped” your cannabinoid fraction, continue to ramp up you mantle 3-5 degrees until you do so.

175-190C is where the fractions that will look most like distillate start coming out and it’s important to let them deplete and work temps up slowly while monitoring the vacuum levels carefully. These fractions have a distinct odor, which a lot of people complain about – It’s due to rushing the distillation during this step. The key takeaway here is if your head vapor temperature probe isn’t reading ATLEAST 158C, you are NOT pulling anything worth collecting. Not Yet. Condenser temperature should be ramped up here to 65C (if your system has vacuum lines), or 85C (if you have a hard-pipe system without GL connections).

At these temperatures, remember that cannabinoids distill out of the flask as a liquid, not a gas – If you see a golden liquid coming out of the condenser discharge but there is little to no activity in the head (especially the vigeroux), it is not the fraction you seek! Keep a close eye on your head vapor temperature as well as your in-system vacuum depth.

Fast Pass Procedure

Now that you have “popped” your THC or cannabinoid fraction – you can ramp your mantle temps slowly upto 200-220C. There are many mantles with different heating elements and rates of heat retention/distribution – regardless of the advice being offered here – I personally would not ramp the mantle past a point at which the vapor temperature exceeds 200C – this will largely depend on your vacuum levels in the system. The purpose for this steep increase is to accelerate the rate of distillation and get everything of value out of the boiling flask as fast as possible as cleanly as possible – feel free to tweak your individual preferences for this as needed. I generally do the bulk of my fraction refining during second pass where stir bar RPM speeds will play a larger role in the overall success.

Winterization: Filtration and Vacuum

More on Winterization

Now that you’ve pulled your alcoholic vessel of fatty crude soup out of the freezer, you are ready to start de-fatting the solution. Unless you are a fan of watching paint dry, you may want to carefully plan how to tackle the next step. The temptation here will be to pour it all out into your tabletop Büchner funnel on full vac and force it through the smallest pore filter-paper you can buy. Unfortunately, unless you have a sophisticated multi-stage filtration system ready, you are in for a world of frustration, abysmal flow rates, and just an all-around bad time. This is the number one issue most smaller labs fail to scale properly!

Don’t worry we will have a thorough SOP for you in the next article, but we are big proponents of teaching people to fish rather than just giving them the fish. The more you learn about this process the easier it becomes to troubleshoot later if there are any issues. Let’s talk briefly about proper filtration protocol and how to select the correct paper mesh size, filter media, and pressure.

Filter Screen Mesh Sizes and Filtration Media

The first filtration is usually the slowest because it will contain most of the fats. The way to ensure it is a smooth experience is to use a larger pore paper to do an initial “Rough Cut”. We usually recommend a 50-25um filter for fast flowrate. The second filtration can be done at 5-8um/micron at which point you should not have any more coagulated particulate in your solution. Now remember – lipids do coagulate at different concentration levels. Another overnight freezer treatment should be performed followed by another 5-8um/micron filtration to ensure proper winterization.

A great way to keep your filter from clogging is to select a 100-350um porous media and create a filtration cake on top of the paper. This promotes flow rate by protecting the pores of the paper form becoming overwhelmed. When flow rate slows, you can scrape the top layer of the cake to remove accumulated fats and restore filtration speeds. Some media can even promote the removal of more than just large particulate but heavy metals and even pigment compounds via chemisorption and/or electrostatic absorption.

ColumboLabs has a great solution for this initial filtration called RapidFlow. It is a proprietary blend of naturally porous minerals which aids in filtration of during winterization and degumming. Activated adsorbents in the blend help trap triglyceride bodies more effectively than silica or diatomaceous earth on their own. The specially engineered media has a propensity to cling on to fats and gums on a molecular level which promotes the most effective refinement of crude. The media is also a desiccant allowing it to trap excess moisture which may have been picked up by the solvent throughout the winterization process.

Negative (Vacuum) and Positive Pressure

Another aspect to consider is the pressure you apply to the filtration apparatus. The most common type of filter is a vacuum assisted Büchner funnel setup. These come in various sizes and configurations, but all work the same basic way. A vacuum is created which pulls liquid solution through the filter paper trapping the fats on the receiving side while allowing the liquid to flow through the tightly knit pores. A vacuum pump creates the pressure which initiates the flow. There is another method which uses positive pressure and requires a slightly different set-up. In a positive pressure filtration system, an inert gas like oxygen (via air compressor) or N2 is hooked up to a closed-loop vessel which pushes the liquid through the filter instead of pulling it through. In both instances the amount of pressure applied is a big factor in how efficiently the system will run.

When running filtration in a vacuum-assisted system, its important not to apply too deep of a vacuum. What typically happens if you overdo the pressure is the coagulated particles enter deeper into the pore openings of the filtration paper causing a clog. Flow-rate will slow to a crawl and you will need to stop and change out the paper in order to get anything done. This is highly disruptive and time consuming (as well as annoying) and should be avoided. If you have the luxury of a vacuum gauge for your filtration vacuum pump, we typically recommend a range of 300-400 Torr for the initial rough-cut, and slightly deeper (200-300 Torr) for secondary and subsequent filtrations. If using a glass receiving vessel, keep an eye on the flow of the liquid at the discharge – your flow should be even and steady. If the flow starts to spray or spit, you may need to lighten the depth of the vacuum pull (or add more solution to the filter depending on what’s going on up top).

Positive pressure filtration is a mixed bag as there is no one-size-fits-all pressure recommendation. It depends largely on the PSI threshold of the paper you are using. We usually see a range of 25-50 PSI for most equipment although filter-presses could go as high as 100+ PSI. Consult the equipment manufacturer for guidance on proper pressure and flow.

Winterization Loss?

A question we get asked regularly is: “What’s the typical yield loss to fats after winterization?”

This is difficult to answer and depends on several factors; type of crude and post-filtration procedure.

Co2 and BHO crude (primary extraction preformed with a lipophilic solvent) are typically higher in fats than ethanol-extracted crude. We typically see a 10-15% “loss” with these types of crude post-winterization. Ethanol crude quality depends on temperature of the extraction; -46C or colder typically doesn’t extract any fats. Expect a very minimal 3-5% (or less) loss on winterizing etoh crude. We have a whole article devoted to explaining the crude characteristics between different extraction solvents – have a read!

A great method for minimizing cannabinoid loss after filtration:

If you notice that the accumulated fats contain a very yellow pigment, it may be worth rinsing them in some cold ethanol immediately after you finish filtering your main batch of winterizing extract. This is done by pouring a small amount of super-chilled alcohol into the Büchner funnel (enough to fully submerge the fat-cake on top of the filter media/paper) and allowing it to settle into the filter for a few minutes. The cold temperature won’t dissolve the fats but will wash out any residual cannabinoids and terpenes which could still be present in the lipid-mass. You can pull a vacuum to thoroughly dry out the cake. For positive-pressure filtration systems, you may require quite a bit more alcohol to preform a thorough flush through the system – so make sure to keep a few extra gallons in the freezer at all times.

Final Thoughts

Save all your accumulated fats; they can be re-utilized in balms, creams, and salves. Remember – bud trimmings were once considered a useless waste-stream and is now a valuable commodity used to make concentrates. There is no telling what will be possible in the future!

Winterization: Basics

Winterization

Winterization is a process when we dissolve oil in a polar solvent like ethanol and subject it to subzero temperatures for extended periods of time. As the temperature of the solution drops, the solubility of hydrophobic, non-polar compounds (plant waxes) become reduced and they coagulate, forming globs which float in the solution. These globs are then filtered out using varying pore-size screens.

Now the easier-to-read version. When we preform primary extraction – there is usually quite a bit of other biproducts that get extracted other than cannabinoids and terpenes. The most common byproducts are plant waxes (called plant lipids or fats). These are fatty acids which are used to make soaps and other products like lotions, etc. Where distillation is concerned, we want to rid our crude of as much fats as possible because they have a similar boiling point to cannabinoids and will usually carry over into the final product. This will result in cloudy or “waxy” distillate when held up to the light. Distilling unwinterized crude will also noticeably reduce the final yield. The process we put our crude through to remove these compounds is called winterization.

Why Alcohol?

Imagine when you put Vodka in the freezer – it doesn’t turn into ice like water. This is because the freezing point of alcohol is much colder ( -173.5F or -114C for ethanol) nearly 100x the temp for water! You would need a hardcore scientific freezer or liquid nitrogen reactor to make ethanol ice cubes. Plant waxes have a low freezing point just like water, which allows them to precipitate out of alcohol when frozen for a period. Lipids don’t like cold temperatures when they are suspended in a hydrophilic medium. Have you ever put chicken or beef broth into the fridge and looked at it the next day? Chances are there are fatty lillypads floating around in your soup after 8+ hours in a chilly environment. This is essentially what we are trying to achieve with our crude before we filter out all the solids.  Ideally for a thorough winterization, you want to go as cold as possible but typically -40C is adequate. Remember also that fats also coagulate at different saturation levels so multiple freezing stages with filtration in between is highly recommended for this process to be thorough.

Filtering out the Waxes

After the alcoholic solution is allowed to sit in the cold for a while – the hydrophobic compounds will reveal themselves to the naked eye in the form of globules. The globules of frozen waxes are then removed through a process of filtration through a series of varying-size screens using a Büchner funnel or another filtration device. The results are quite interesting to watch! What was before a murky miso-soup-like concoction of fatty crude and ethanol transforms into a crystal-clear liquid and we are one step closer to distillation. There are many more things to consider during filtration such as filter mesh size, filter media, etc. We will cover this plus provide an SOP for proper winterization in subsequent articles.

GL Connections and Wide Bore Set-ups (SPD)

Vacuum Lines

Originally, SPD systems came with a ¼’’ GL connection through which the vacuum would pass. Vacuum lines were used to connect each gl-14 barb to daisy-chain the system together. This worked perfectly with smaller systems like the 1L and 2L stills, but we discovered that the larger we scaled our boiling flask, the harder it became to sustain deep vacuum and evacuate the system during a run. There were other issues with this design; we soon discovered that certain types of material would “off-gas” and interfere with the distillation by disrupting the vacuum depth. Silicone and rubber lines were the primary culprits when we exceeded vacuum depths of 300 micron or 0.300 torr.

Clogging

There were also other issues such as gaseous fractions condensing at the openings of the GL ports causing clogs and disrupting the distillation process. This created an odor issue with the final distillate – and not all the compounds were being cleanly separated as before. Subsequently, the connections were made wider and 3/8’’ gl-connections were employed to fix the issue. We also hanged the type of material we used for our vacuum lines to a more rigid polymer and this required us to grease and clamp each barb fitting to ensure no leaks would disrupt the run.

Full Bore

We noticed the vacuum depth increase exponentially when we removed the bottleneck between the pump and the cold trap – even more so after we removed all lines and allowed for a full wide-bore path from the point of distillation. This caused some small issues in the short-term, although we were now achieving ultra-deep vacuum, our pumps were being loaded up with so much vapor during the volatile/terpene fractions, a dual-pump solution had to be employed and more cold trapping power added. Since then the tech has been much improved upon allowing for a more efficient and effective process.

Summary

If you are choosing to buy an SPD set-up, we highly recommend a full-bore configuration for maximum versatility and fraction resolution.

Stir Bars

Stir Bars:

Having an agitation method is very important during distillation – especially when we have a multitude of compounds in the boiling flask to separate. This is due to relative volatility – which is the comparison of varying vapor pressures of the compounds in the crude. Modulation of the stir bar speed helps separation of more volatile compounds from the rest of the pot. It also keeps the temperature of the boil more evenly distributed throughout the flask.

Increasing the agitation causes more vapor to flow into the system which sometimes may drop vacuum performance, so ramp up slowly to save your pump. Experiencing a rapid decline in vacuum depth when increasing RPMs is a clear indicator of ongoing distillation of volatiles – ideally this needs to conclude prior to pulling your main body of cannabinoid distillate or there may be unwanted odor to the finished product.

Egg-shaped bars work exceptionally well in round bottom flasks because they conform to the shape of the vessel. Rare-earth, which is a highly magnetized compound, works best to stay engaged to the magnetic drive of the mantle – Rare earth stir-bars are worth the extra cost. You also want to get the largest (longest) stir bar possible to maximize the continuous homogeneity of the boil;

  • 5’’ length for 22 or 20L SPD systems
  • 5’’ – 3’’ length for 12, 10 and 5L SPD systems

If you aren’t sure about a new stir-bar you’ve purchased for your system, throw it into an empty boiling flask (or one filled 1/3rd with water) and set into the mantle – this will allow you to observe the RPM threshold as you ramp up the speed. If doing this process with water, there should be a very clear vortex in the center of the flask with the liquid visibly shifting rapidly.  Note the speed at which the motion of the stir-bar becomes erratic and it eventually loses its position – this will be your maximum RPM, try to stick to ¾ of your max during distillation.

When distilling crude, you should aim to increase stir bar speeds as quickly as possible while progressing through the fractions (without knocking your bar out of position). This is important to prevent bumping, and to thin out the more viscous compounds allowing the low-boiling fractions to escape the flask.

Rotary Vane Vacuum Pump – Maintenance

Tips for maintaining your vacuum pump:

Best indicator for vacuum pump performance is a reliable digital vacuum gauge.

Having a vacuum gauge on your pump will allow you to figure out when the pump needs to have an oil change or be taken in for repair. Checking the pump’s ultimate depth is advantageous to do prior to each run to ensure a successful distillation.

When doing cannabinoid distillation with short path, I always shoot for an ultimate vacuum of 10 micron (0.010 torr) or better when running the pump “dry” or separated from the system. Be wary of how you measure this number – best way is to find a gauge with the same coupling size as the inlet port for your pump. IE: if your pump has a KF25 inlet, connect a gauge which has a KF25 connector. Avoid vacuum lines when possible as the turbulence caused by the bottleneck will yield inaccurate results. Keep in mind also that not all gauges operate the same. My experience with Digivac KF25 Bullseye gauges for example showed a 25-26 micron reading on a freshly changed Edwards E2M28. My Instrutek KF25 Stingers however, showed 4.9 micron on the same pump after a quick switch-over. The important thing to consider here regardless of which gauges you use is to determine and know the baseline depth for your pump when it is clean. If you can get back to the same baseline numbers after an oil change, you know you are doing proper maintenance on your pump.

Why do we need to change the oil?

During the run, especially during the distillation of high volatiles/solvents/terpenes – you may notice that your pump read-out is much higher than what it can achieve when isolated from the system. This is a sign of vapors from the boiling flask bypassing the cold trap. It is for exactly this reason that your pump oil will need to be changed frequently in order to stay at peak performance.

How do you know if it’s time to change the oil before you start a distillation? Start your pump and isolate it from the system with only the vacuum gauge and give it 10-15 minutes to warm up. If it doesn’t reach, it’s known ultimate vac level, within that time period – its time to change the oil. Keep reading.

Step – by – step

The following SOP will outline the full maintenance steps to changing rotary vane vacuum pump oil and maintaining its longevity as well as determining its ultimate vacuum (especially if you don’t know what it is).

  1. Isolate the pump from the system or detach from your system manifold – attach just a digital vacuum gauge directly to the vacuum port.
  2. Start the pump and allow it 10-15 minutes to pull a deep vacuum on the instrument – notate the reading.
  3. Open the ballast and notate the depth once the reading stops climbing. Allow the pump to run this way for 1-2 hours with the ballast open.

You will notice the pump will be very hot upon your return – this is normal. Your vacuum reading should have gotten deeper. Notate the number with the ballast open, close it, and notate that number.

  1. Now you can shut off your pump and immediately change the oil while the machine is hot. Use protective equipment and drain the oil into a pan or some other kind of container. Its best to have the pump elevated at an angle as sediment from the inside of the oil reservoir is allowed to flow out.
  2. Once all the oil has drained, tip the pump to allow all the remaining sediment and leftover drops of oil to leave the reservoir and put the cap back on.
  3. Fill ¼ with fresh oil and turn the pump on. Allow the pump once again 10-15 minutes to attain deep vac and record the reading.

If you are still not satisfied with your ultimate vacuum depth, consider buying a cleaning agent or flushing fluid to add into the reservoir. Run pump for duration as instructed and drain as before. This is like putting oil fuel cleaner into your gas tank of your car.

If for some reason your pump is having trouble maintaining vacuum or can’t achieve a previously attainable ultimate vac, this should be a sign that something is wrong. A rebuild may be required.

What does the ballast do?

Opening the gas ballast allows air into the oil reservoir which makes the pistons work harder to drive the motor – this generates more heat which helps purge the vacuum oil of water, certain volatiles, and terps (hence the smell). The additional heat also loosens up the caked-up garbage on the pistons and the walls of the oil reservoir.  Therefore, you should do your oil change immediately after shutting the pump off after a long period of operation while contaminants haven’t had a chance to settle and cool.

You may opt to open the pump’s ballast during the terpene portion of the run to allow the contaminants to leave the oil reservoir in the form of a vapor – warning this will make your lab very stinky. Most vacuum pumps come equipped with an optional oil mist filter – these filters have an exhaust port to which you can attach a hose and plumb to exhaust ventilation.

Exhaust & Mist Filters

Many of the pumps we use will come with a mist or exhaust filter. Their purpose is to limit the odor coming out of the pump and prevent oil mist from diffusing into the lab. As they accumulate oil, most will have a sight window with an indicator for replacement or drainage. Keep them clean and don’t cover them!

Make sure that you are not restricting the exhaust flow because this may pop the seal of the pump and you will need to bring it in for repair. The pumps need to be able to breath – they can hold a tremendously deep vacuum but even a little bit of pressure build-up and you will have a dud before long. It is for this reason that you should keep an eye on your mist filter and make sure the oil it’s catching doesn’t accumulate above the threshold or it will “drown” the pump. Drain or change out the mist filters as needed on a regular basis.

Dealing with stinky exhaust

The best way to avoid breathing in “fishy pump terps” in your workspace is to plumb the exhaust outside, but sometimes this isn’t an option. Another cool trick is to attach a tight-fitting hose to the pump exhaust and submerge the other end in a bucket of water + dawn liquid dish soap. The unpleasant smells will become trapped by the heaviness of the soap + water mixture and the resulting exhaust fumes will smell like dawn soap vs. degraded terpenes.

Decay of Organic Compounds

Decay of Organic Compounds

There are several factors to consider when preforming any kind of organic chemistry; organic matter will decay and deteriorate naturally over time. Therefore we put produce into the refrigerator/freezer to extend its longevity. Refrigeration lowers the temperature and slows down the natural process of decomposition or the breakdown of organic compounds. Heating will produce the opposite result.

When we cook food – we break down matter in a menagerie of fats, salts, acids – cooking is not unlike distillation – it’s basically chemistry we preform every day in order to survive! Understanding how to speed up and slow this process is essential to distillation and extraction of cannabis concentrates in general.

Another factor to consider is what’s in the atmosphere. The very air we breathe contains a powerful compound which interacts with organic and non-organic matter producing subtle changes – it’s called oxygen and it causes a phenomenon called oxidation.

Oxidation is the process when oxygen combines with an element changing its appearance and chemical composition. When iron reacts with oxygen, it changes to rust – this is an example of oxidation. When fire burns up a wooden log, this is also an example of oxidation. This is also true for organic matter – such as cannabis resin etc. Heat can speed up this process considerably because the molecules become more excited and can move around freely. Therefore, it’s important to distill cannabinoids in an environment devoid of all oxygen, especially when we subject our resins to heat.

Most extraction is done under very cold conditions, but sometimes it’s necessary to apply heat. In the case of cannabinoids however – applying too much heat would vaporize them into a cloud i.e. smoking flower – so how do we capture and re-condense this vapor into a concentrated form?

Vacuum distillation is used when the boiling point of the desired compound is difficult to achieve or will cause the compound to decompose. THC for example has a boiling point of approx. 425C at atmosphere – but if we were to apply that kind of heat without vacuum, everything in the resin would be turned into dust! It is only at 300 micron or 0.3 mTorr that we can fraction off THC at a reasonable 184C. 157C boiling point can be achieved at 50 micron or 0.05 mTorr.

Why is this important? The journey of extraction and distillation will subject our wonderful cannabis plant to many of these conditions and it’s important to understand what is happening to the cannabinoids and terpenes during the process and how they are affected. Knowing all the variables of decay and decomposition allows us to create conditions which allow us to improve efficiency and boost yields of the specific compounds we are looking to isolate.

Decarb & Degas: Avoiding SPD Boilover

The purpose is to get rid of residual solvent and other highly volatile compounds before we subject the material to ultra-deep vacuum in preparation for our cannabinoid extraction. In a sense it’s a prophylactic step which allows us quickly cut through a section of compounds which behave very violently under deep vacuum and tend to bypass the cold trap and end up in your vacuum pump. Ideally this process should be done in a reactor or on a hot-plate (with proper ventilation).

I’ve already poured my crude into the SPD flask!

Can you decarb/degas in my SPD? Absolutely. It may take a long while, but it can be done. Just be very aware of your vacuum depth and set all the condensers in the system to their absolute coldest temperature.

Start by heating your crude to 65-75C in the mantle, stir bar off! Slowly ramp your vac depth until you see a consistent boil. Increase temps 5-degree increments to 100C until there is very little to no activity in the flask. At this point you should start agitating with the stir bar very slowly but keep your hand on the vacuum bypass/breather valve (sometimes called the oh-shit valve) just in case the contents start rising too quickly and crest past the ¾ point of the flask.

If you have a separate pump other than your deep-vacuum pump to use for this process – this is the time to put it to use. We are big fans of chemical diaphragm pumps since there is no oil to change and the internals can withstand a litany of nasty vapors – just make sure you plumb the exhaust to a ventilation source to carry the nasty smells out of your immediate work environment.

Pro Tip: You can run a hose from your pump’s exhaust port to a bucket filled with soapy salt water. We have tried this with a heavy dose of dawn liquid detergent, and it seems to trap the gross smells within the water as the vapor tries to percolate through the heavy suspension.

Be careful! If you ramp your vacuum too  quickly and create too much of a bottleneck for the volatiles trapped inside the crude – the light compounds will bubble up in volcanic fashion and spill up and over into the head, condenser, and receiving flasks. This is called a boil-over and don’t worry it happens to everybody. If you see this happening (crude rising quickly), you need to lay off the vacuum pressure – sometimes so far as to let atmosphere back into the system to settle the contents of the boiling flask back down.

Summary

If (when) this happens to you and you got it under control – take a deep breath, shut everything down and carefully start taking your system apart for cleaning. It may feel defeating but take comfort in the fact that it has happened to everybody at some point. I personally had a litany of boil-overs, first from inexperience, and later from not paying enough attention!  Have some rags and a spray-bottle of solvent ready for when disaster strikes – and invest in a breather valve so to help prevent future boilovers.

Tips for a Successful Distillation

Tips for a Successful Distillation

The most frequent thing we are asked is what people can do to get better at distillation with an SPD. Simple answer is: do more runs and learn from your mistakes… Fail better! But aside from understanding from visual cues – it really does help tremendously to have the right instruments to work with. Give yourself the competitive advantage by having measurable variables to compare every time you run a batch! Below you will find the most essential gadgets you should be outfitting your system in order to be successful. We’ve put together a little excel log so you can keep track of your run progress – this will help you to see the changing variables in a more organized manner and if your still lost – you can show more experienced distillers (like us) your data to get tips for next time. Download it at the bottom of this article.

Monitoring System Temperature:

Get yourself some good temperature probes! (preferably some digital ones)

Where they need to be:

  1. Inside the boiling flask to measure the temperature of the starting material as it progresses through the various fractions. This probe is usually connected to the boiling flask heating element which you can set accordingly.
  2. Inside each distillation head to measure the vapor temperature of the fractions discharging into the condenser(s).

Even temperature distribution is very important in the boiling flask when you are trying to coax fractions out at deep vacuum levels. As the various compounds travel up the distillation head in either vapor or liquid form, the energy of the reaction will cause temperatures to rise through the column thus allowing for other compounds to “Carry Over” Its important to keep progressing through the various fractions and not allow for steep temperature fluctuations within the head. Therefore, an accurate bottom mantle along with an insulation method or a heated top mantle are highly recommended. Keeping a record of the rising temperatures in the distillation head is also a must – therefore a high-accuracy digital probe to measure and record vapor temps is by far the best investment you can make as both a novice and an expert SPD operator.

Let’s look at some common equipment used for heating and insulating:

Types of mantles:

Bottom heated (pic)

Top and Bottom Heated (pic)

Oil Jacketed *Not typically used for SPD, this is a common method to heat other large cauldron-style vessels such as reactors and also the outside bodies of WFE distillation Systems (pic)

Insulation types:

Glass Stove Rope (pic)

Electric Heat rope (Pic)

Foil (Pic)

Silvering (For Glass)

Vacuum Insulation (Glass/SS)

Monitoring system vacuum:

Vacuum Gauges (Digital)

Having a few good vacuum gauges plumbed into the system and specific points will be a huge timesaver and will help you understand what is going on in the system and which stage of the process you are at. Using this data along with the readouts from the temperature probes allows us to develop our run methodology, create SOP’s, and control our variables.

In a typical SPD system, you will find one vacuum gauge affixed to read vacuum inside the distillation system – the location varies depending on which glass manufacturer you are using. Some vacuum ports are located at the head condenser discharge (pic). Some are located further away, but prior to the last cold trap before the vacuum pump manifold. There is nothing wrong with having more than two points of vacuum being read, the more data we have the more we can learn about what’s happening inside the system! The last vacuum gauge is typically located directly on the Vacuum pump manifold – it should be set-up in such a way to be able to isolate from the rest of the system and tell you what your pump’s ultimate vacuum is when its not pulling vapors. We typically recommend no more than 20 micron or 0.020 torr as the ultimate vac from your main deep-vacuum pump.

Vacuum Grease:

The best way to ensure a proper vacuum seal is to use a good vacuum grease. There are two types of grease we recommend you should look at. The first is Dow Corning – which is a standard food-grade safe vacuum grease which is popular. I would personally recommend this for any glass joints which will ever come in contact with final product such as the receiving flask or product pathway glass. It has some limitation though – it doesn’t like temperatures above 200C and is soluble in alcohol. This could be a potential issue as we often do push our first pass beyond 200C on the mantle so another solution is needed for this.

Apizion 501 is the other product we use – it is an ultra high vacuum grease that is rated to 13 scale vacuum – used in scientific laboratories and at NASA. This product is very expensive compared to Dow Corning so use it sparingly. It has a high temperature threshold and can handle temps well above 200C so its great for use on or near the boiling flask joints.

What we like to do is use both at the same time. We grease the outer portion of the glass joint with Apizion 501 to ensure a tight seal. The inside (potentially distillate touching side) we apply a bit of Dow Corning lubricant. Its important to slowly “massage” the joints back and fourth after putting your system together and also when applying vacuum to ensure even distribution and to work out any potential air bubbles.

Keep and eye on your in-system vacuum gauge when massaging the joints back and fourth to ensure the fluctuations are progressively moving towards a deeper vacuum.

 

Recording your Progress:

Keep a log of the entire run on a spreadsheet for reference:

There are numerous techniques for logging your SPD runs – and doing so will allow you to compare data from all the various instruments such as temperature, vacuum levels, and event visual ques. You will notice subtle changes which will help you determine how to proceed.

The number one reason distillate comes out discolored or with an odor is because the operator rushed through the fractions due to a lack of understanding when to raise mantle temperatures. By having these vital instruments installed and recording the data, you will be be able to spot an increase in vacuum depth and slight decrease in head vapor temperature as a signal that the current fraction is depleting and that it is time to ramp up the mantle.

We’ve created a basic excel spreadsheet to allow you to log your run progress. Get to know your system and refine your process by doing it the old-fashioned way. The good news is that there are products we will soon feature which will allow you to not only automatically log all this data, but to automate your process too! Stay tuned.

Distillation and Equipment

What is Distillation?

The textbook definition of Distillation:

“the action of purifying a liquid by a process of heating and cooling”

In our world – distillation occurs when we separate the desired compounds (Cannabinoids and Terpenes) from oil/resin using heat, under vacuum. There are numerous companies offering equipment and training to achieve this – we’re here to help sort through all the noise.

Types of Distillation Equipment for Cannabis

At a Glance

  • Short Path
  • Spinning Band
  • Wiped Film / Rolling Film

Short Path:

Short-Path distillation systems or “SPD’s” have become a buzzword in the cannabis industry. They feature a heating mantle with a boiling flask which is manipulated under vacuum to “fraction” off compounds. As heat/vacuum increase incrementally, a variety of compounds distills away from the crude in the boiling flask and condense in another part of the system. Once a desired temperature and vacuum pressures are achieved, the operator can isolate the cannabinoid fractions in separate receiving vessels, away from the rest of the derivatives. The cannabinoid fractions can be re-distilled in a fresh boiling flask to refine and purify further.

Because of the low cost of entry, many aspiring extract artists and start-up labs alike choose this option over the other more expensive varieties of distillation equipment. Don’t be fooled by the price-tag because mastering the short-path is a tedious process! Depending on the type of crude material you plan on running through your SPD, you may need to invest in additional equipment such as chillers/heaters and aux condensers. Luckily – ColumboLabs has you covered with everything you need to know!

Systems typically range from $5k – $40K for some of the larger volume vessels and are highly modular and customizable.

  • Pros: Low cost of entry and short lead times for systems. Highly versatile and customizable. Many vendor options ranging from Economy to Super high end.
  • Cons: High learning curve. Capacity and through-put limitations. Non-continuous operation.

Spinning Band:

Like the SPD, the spinning-band systems feature a heating mantle and a boiling flask which contains the starting material or “Crude”. The main difference is a large corkscrew-shaped rod spins in the way of the “fractions” on their way up through the system. This allows for heavier compounds to climb slower up the “head” of the distillation still = more precise separation.

These systems are highly versatile and with the right modification can achieve high through-put. We tend to only see these in analytical and R&D facilities where a high level of refinement is desired and tight parameters are required. Great choice for refining terpenes and hunting/isolating rare cannabinoids/other compounds.

Systems typically range from $60k – $140K and are outfitted with a slew of analytical/data-collection equipment.

  • Pros: Highly versatile and customizable. High Efficiency. Continuous operation.
  • Cons: High cost of entry and long lead times. One primary manufacturer. Capacity and through-put limitations.

Wiped Film / Rolling Film:

Wiped Film systems or “WFE” (Wiped Film Evaporators) are probably the most complex systems to explain at first glance. Imagine a vertical heated tube through which crude is slowly fed from top down along the inside edge. Now imagine at the center of this tube is a set of blades (or sometimes rollers) which spin at high speeds smearing the incoming crude evenly around the inside as it slowly descends downwards in a “thin film”. Meanwhile at the center of this heated tube is a rod (condenser) which is set to a lower temperature than the outside tube. The results are fascinating – as the heated crude descends downwards through the system, any and all compounds that can evaporate off the sides re-condense around the center rod, and flow downwards into a receiving flask. The rest of the unevaporated sludge continues to flow downward along the inner edge of the heated tube and collects in a separate vessel deemed “Reject” – which is then discarded or re-ran to ensure yield thoroughness.

Systems typically range from $100k – $500K+ and are the popular choice for large manufacturers of distillate because they can be scaled to do immense throughput in a short amount of time.

  • Pros: High throughput, high efficiency. Continuous operation. Scalable.
  • Cons: High cost of entry and long lead times. Low versatility, many passes required to achieve desired level of product purity.

Summary:

As they say, there’s many of ways to get the job done when considering which equipment to use. Distillation is highly rewarding and fun – but you must keep in mind the scope of your operation when designing your lab. Cost of the equipment vs. ease of use is also a factor; you can get a lot more bang for your buck with SPD, but sometimes going the way of WFE is the logical next step for scaling as well as continuous operation. For some of the more exotic separations and refinement of terpenes, a spinning-band system may be required. With cannabis decriminalization and regulation going mainstream, manufacturing is on the rise! Understanding what type of system you will purchase can make a huge difference for your future success.