On June 29, 2021, Cannabis Industry Journal is hosting the Cannabis Extraction Virtual Conference. From Noon to 5 pm EST, you’ll get access to five veterans of the extraction market discussing a variety of topics related to the ins and outs of extracting cannabis and hemp.
Hear from subject matter experts who will share their perspectives on cannabis and hemp extraction, supercritical CO2 extraction, post-processing, risk management, hazards and controls, optimization, closed loop hydrocarbon extraction, machine learning algorithms and more.
Alex Hearding, Chief Risk Management Officer at the National Cannabis Risk Management Association (NCRMA) will kick things off with a session exploring the Hazards and Controls of Extraction with Liquified Petroleum Gases. Dr. Markus Roggen, Founder & CEO of Complex Biotech Discovery Ventures, will follow that up with a discussion surrounding the kinetics and thermodynamics of cannabis extraction.
Other talks from the Cannabis Extraction Virtual Conference include:
The Quest to Discover the Limits of CO2 Extraction
Jeremy Diehl, co-founder & CTO of Green Mill Supercritical
The Future of Cannabis Concentrates: Developments in Hydrocarbon Extraction and Manufacturing
Michelle Sprawls, Laboratory Director at CULTA
Process Scale Up in the Cannabis/Hemp Industry
Darwin Millard, Committee ViceChair on ASTM International’s D37.04 on Processing & Handling of Cannabis
There are many factors that can lead to the challenges people face when scaling up their processes. These challenges are not unique to the cannabis/hemp industry, but they are exacerbated by the consequences generated from decades of Reefer Madness. In my time operating in the cannabis/hemp space, 15+ years, I have seen established equipment vendors and sellers of laboratory supplies, like Sigma-Aldrich (now Millipore-Sigma), Fisher-Scientific, Cerilliant, Agilent, and others, go from reporting individuals inquiring about certified reference materials to setting up entire divisions of their companies to service the needs of the industry. Progress. But we are still a fledgling marketplace facing many challenges. Let’s look at a few specific to process scale up.
Darwin Millard will deliver a presentation on this topic during the Cannabis Extraction Virtual Conference on June 29. Click here to learn more.Equipment Availability: Lack of available equipment at larger and larger process scales can severely impact project timelines. Making not only equipment acquisition difficult, but also limiting the number of reputable equipment manufacturers you can work with.
Non-Linear Expansion: NEVER assume your process scales linearly. Perhaps one of the most avoidable mistakes during process scale up. You will quickly find that for many processes you cannot just put in a larger unit and expect a proportional increase in output. This is because as process equipment increases so to must utilities and other supporting infrastructure, but not only that, process vessel geometry, proportions, and design are contributing factors to process efficiency as your scale of operations increases.
Hazardous Material Quantities: Just as important to the process as the equipment are the solvents and reagents used. As your scale of operations increases so does your demand and production of hazardous materials; solvents including carbon dioxide (CO2), ethanol, and liquid petroleum gases (LPG) like Butane and Propane are obvious hazards, but so too are the refrigerants used in the chillers, fuels used to power generators, steam created to heat critical systems, and effluents and wastewater discharged from the process and supporting systems. Not every municipality wants thousands of gallons of flammable substances and hazardous waste being generated in their backyard…
Contractor/Vendor Misrepresentation: Finding out in the middle of you project that your contractor or equipment vendor has never set up a system at this scale before is never a good feeling. Unfortunately, contractor and vendor misrepresentation of qualifications is a common occurrence in the cannabis/hemp space.
If all this was not bad enough, all too often the consequences of improper planning and execution are not felt until your project is delayed or jeopardized due to misallocation of funds or undercapitalization. This is especially true when scaling up your production capacity. Now let’s look at some ways to avoid these mistakes.
The Rule of 10
When scaling up your process, NEVER assume that a simple linear expansion of your process train will be sufficient. It is often the case that process scale up is non-linear. Using the Rule of 10 is one way of scaling up your process through a stepwise iterative approach. The Rule of 10 is best explained through an example: Say you are performing a bench-top extraction of a few grams and want to scale that up to a few thousand kilograms. Before jumping all the way to your final process scale, start by taking a smaller jump and only increase your bench-top process by a factor of 10 at a time. So, if you were happy and confident with your results at the tens of grams scale, perform the same process at the hundreds of grams scale, then the thousands of grams scale, tens of kilograms scale, and so forth until you have validated your process at the scale of operations you want to achieve. By using the Rule of 10 you can be assured that your process will achieve the same yields/results at larger and larger scales of operation.
Scaling up your process through an iterative approach allows you to identify process issues that otherwise would not have been identified. These can include (but by no means should be considered an exhaustive list) improper heat transfer as process vessels increase in size, the inability to maintain process parameters due to inadequately sized utilities and/or supporting infrastructure, and lower yields than expected even though previous iterations were successful. However, this type of approach can be expensive, especially when considering custom process equipment, and not every processor in the cannabis/hemp space is going to be in the position to use tools like the Rule of 10 and instead must rely on claims made by the equipment vendor or manufacture when scaling up their process.
The Cannabis/Hemp Specific Process Equipment Trap
How many times have you heard this one before: “We have a piece of process equipment tailor-made to perform X,Y,Z task.”? If you have been around as long as I have in the cannabis/hemp space, probably quite a few times. A huge red flag when considering equipment for your expansion project!
Unless the equipment manufacturer is directly working with cannabis/hemp raw materials, or with partners who process these items, during product development, there is no way they could have verified the equipment will work for its purported use.
A good example of this are ethanol evaporation systems. Most manufacturers of evaporators do not work with the volumes of ethanol they claim their systems can recover. So how did they come up with the evaporation rate? Short answer – Thermodynamics, Heat Transfer, and Fluid Mechanics. They modeled it. This much surface area, plus this much heat/energy, with this much pressure (or lack thereof), using this type of fluid, moving through this type of material, at this rate of speed, gets you a 1000-gal/hr evaporator or some other theoretical value. But what is the real rate once an ethanol and cannabis/hemp solution is running through the system?
For a straight ethanol system, the theoretical models and experimental models are pretty similar – namely because humans like alcohol – extensive real-world data for ethanol systems exist for reference in designing ethanol evaporators (more accurately described as distillation systems, i.e. stills). The same cannot be said for ethanol and cannabis/hemp extract systems. While it is true that many botanical and ethanol systems have been modeled, both theoretically and experimentally, due to prohibition, data for cannabis/hemp and ethanol systems are lacking and the data that do exist are primarily limited to bench-top and laboratory scale scenarios.
So, will that 1000-gal/hr evaporator hit 1000-gal/hr once it is running under load? That’s the real question and why utilizing equipment with established performance qualifications is critical to a successful process scale up when having to rely on the claims of a vendor or equipment manufacturer. Except this is yet another “catch 22”, since the installation, operational, and performance qualification process is an expensive endeavor only a few equipment manufacturers servicing the cannabis/hemp market have done. I am not saying there aren’t any reputable equipment vendors out there; there are, but always ask for data validating their claims and perform a vendor qualification before you drop seven figures on a piece of process equipment on the word of a salesperson.
Improper design and insufficient data regarding process efficiencies on larger and larger scales of manufacturing can lead to costly mistakes which can prevent projects from ever getting off the ground.
Each aspect of the manufacturing process must be considered individually when scaling your process train because each element will contribute to the system’s output, either in a limiting or expansive capacity.
I go further into this topic in my presentation: Challenges with Process Scale Up in the Cannabis/Hemp Industry, later this month during Cannabis Industry Journal’s Extraction Virtual Conference on June 29th, 2021. Here I will provide real-world examples of the consequences of improper process scale up and the significance of equipment specifications, certifications, and inspections, and the importance of vendor qualifications and the true cost of improper design specifications. I hope to see you all there.
Supercritical carbon dioxide (CO2) extraction is a processing technique whereby CO2 is pressurized under carefully controlled temperatures to enable extraction of terpenes, cannabinoids and other plant molecules. Once the extract is obtained the crude is often subjected to an ethanol winterization process to remove chlorophyll, fats and waxes.
Green Mill Supercritical is a Pittsburgh-based manufacturing and engineering company focused on cannabis and hemp extraction. The company offers a range of CO2 extraction equipment where users can tune and control their extraction methods. They recently announced a technology advance enabling winterization in-process, which has the potential to remove the need for ethanol winterization.
We spoke with Jeff Diehl, director of marketing at Green Mill Supercritical, to learn more about the new process. Jeff was working in the tech industry in San Francisco in 2017 when he was invited to join Green Mill by his cousin, Jeremy Diehl, who is the founder and CTO.
Aaron Green: Before we get to your new technology, can you explain what industry trends you are watching?
Jeff Diehl: A big thing that I watch is the premium extract space. More and more consumers are demanding higher premium extracts. They want differentiated products. They want products that are safe and that have some kind of meaningful connection to the specific plant from which they came. Right now, CO2 plays a small role in the market for those products. Most premium products are generated through hydrocarbon extraction. So, I am watching how people are using CO2 to create the next generation of safe, premium products.
Aaron: What is the normal process for a CO2 extraction today?
Jeff: The current CO2 extraction process generally consists of two major phases to producing your final extract. In the first phase, you have extraction where you get your crude product. The second phase is post-extraction where you do cleanup to get your refined oil. Within that post-extraction phase, most operations include an ethanol-based winterization process.
Aaron: What does the winterization step do, exactly?
Jeff: Winterization is about removing waxes. Your main extraction is considered crude because it’s got a lot of materials from the plant that you don’t want. The large majority of unwanted material is waxes. Winterization is the process of using a solvent, traditionally ethanol, to separate the waxes from the cannabinoids. There are multiple challenges inherent in ethanol-based winterization that introduce cost, time and product loss. It’s terribly inefficient. Plus, there will always be residual ethanol left in your final product, and that’s not something consumers appreciate.
Aaron: You’ve recently announced a new process at Green Mill that moves the winterization step into the supercritical CO2 equipment. Can you explain how that works?
Jeff: With our process, which we call Real-Time Winterization, there is no ethanol involved in winterization anymore. It is all done with CO₂ during the primary extraction. That’s the major advance of our process and although it has been attempted before, no one has succeeded at doing it in a viable way. You take a process which is normally four days – one day for CO2 extraction and three days for ethanol winterization – and you do it all in less than a day. We have automated software, sensors and pumps that makes this all possible.
Aaron: How does the quality of the resulting product compare with the new process?
Jeff: You can see the difference right away, if you’re at all familiar with extraction. It just looks clean and bright. Lab analysis has been very positive thus far, but we continue to run tests. Our R&D team has done multiple tests, mostly on hemp and CBD. That’s because we don’t have a license for THC. We’re currently engaging with a licensed partner so that we can collect more data on THC-containing products, so we can give exact numbers. But with CBD, we’ve done multiple tests to validate the method and the technology, and are seeing consistently excellent results in regards to both purity of the product and efficiency of the process.
Aaron: How do yields compare between the processes?
Jeff: From the data that we’ve seen in the industry, it looks like when you winterize with ethanol, you leave anywhere from 5 to 10% of your cannabinoids behind in the waxes. That’s just lost. With Real-Time Winterization using CO2 we have seen recovery rates as high as 99%. We are continuing to investigate that result with testing to make sure it was not an outlier, but in any case, recovery rates look promising.
Aaron: One of the other issues with ethanol is taxes and the ability to find food grade supply. Do you have any perspective you can share on that?
Jeff: There are a number of advantages to moving away from ethanol. The sheer quantity of ethanol is a factor. There are a lot of regulations and fire requirements around managing large quantities of ethanol. The ethanol winterization process itself is not just one process. There are multiple stages, from mixing, to freezing, to filtering, to removing the solvent. These are all opportunities for things to go wrong, so you’re always managing those risks. Multiple large pieces of equipment, including fume hoods, filter skids, cryo freezers and rotary evaporators, are expensive and require heavy management.
I think Elon Musk said the best process is no process. Anytime in an industrial process when you can remove steps in the process, that’s the direction you want to go in. And, that’s what we’ve done. With this recent work, we have effectively removed post processing for certain categories of end product.
Aaron: Do you have any patents on the new process?
Jeff: We have a patent pending on both the method and the equipment, which is allowing us to talk about this as much as we are.
Aaron: So, how does this work if somebody already owns an existing piece of Green Mill equipment? Is this something that can be retrofitted? Is it a software upgrade?
Jeff: There are two components. One is an equipment upgrade, which can be done retroactively for existing customers, and one is a methodology upgrade, which we assist our customers with. The automation software inherently can handle the settings that you need to run the methodology. In fact, it’s that software and the rest of our existing tech stack, the proprietary pump, the triple inline fractionation, the precision and stability of the overall system, that is what made this winterization advance possible.
Aaron: Where are you rolling this out first? And do you plan to go international?
Jeff: International is definitely in the plan, since we’ve already sold systems abroad. We are currently getting ready to announce the opening of our beta program with the new technology. So, we’re not ready to sell this widely at this time, but we are taking submissions from companies that want to get in early and join us at the forefront of CO₂ extraction innovation.
Aaron: Okay, great. Thanks Jeff, that’s the end of the interview.
Remediation of delta-9 tetrahydrocannabinol (d9-THC) has become a hot button issue in the United States ever since the Drug Enforcement Agency (DEA) released their changes to the definitions of marijuana, marijuana extract, and tetrahydrocannabinols exempting extracts and tetrahydrocannabinols of a cannabis plant containing 0.3% or less d9-THC on a dry weight basis from the Controlled Substances Act. That is because, as a direct consequence, all extracts and tetrahydrocannabinols of a cannabis plant containing more than 0.3% d9-THC became explicitly under the purview of the DEA, including work-in-progress “hemp extracts” that because of the extraction process are above the 0.3% d9-THC limit immediately upon creation.
The legal ramifications of these changes to the definitions on the “hemp extracts” marketplace will not be addressed. Instead, this article focuses on the amount of d9-THC that is available in the plant material prior to extraction and tracks a “hemp extract” from the point it falls out of compliance to the point it becomes compliant again and stresses the importance of accurate track-n-trace protocols at the processing facility. The model developed to support this article was intended to be academic and was designed to follow the d9-THC portion of a “hemp extract” through the lifecycle of a typical CO2-based extract from initial extraction to THC remediation. A loss to the equipment of 2% was used for each step.
For this exercise, a common processing scenario of 1000 kg of plant material at 10% cannabidiol (CBD) and 0.3% d9-THC by weight was modeled. This amount, depending on scale of operations, can be a facility’s total capacity for the day or the capacity for a single run. 1000 kg of plant material at 0.3% d9-THC has 3 kg of d9-THC that could be extracted, purified, and diverted into the marketplace. CO2 has a nominal extraction efficiency of 95%, meaning some cannabinoids are left behind in the plant material. The same can be said about the recovery of the extract from the equipment. Traces of extract will remain in the equipment and this little bit of material, if unaccounted for, can potentially open an operator up to legal consequences. Data for the initial extraction is shown in Image 1.
As soon as the initial extract is produced it is out of compliance with the 0.3% d9-THC limit to be classified as a “hemp extract”, and of the 3 kg of d9-THC available, the extract contains approx. 2.8 kg, because some of the d9-THC remains in the plant material and some is lost to the equipment.
Dewaxing via Winterization and Solvent Removal
Dewaxing a typical CO2 extract via winterization is a common process step. For this exercise, a wax content of 30% by weight was used. A process efficiency of 98% was attributed to the wax removal process and it was assumed that 100% of the loss can be accounted for in the residue recovered from the equipment rather than in the removed waxes. Data for the winterization and solvent recovery are shown in Image 2 and 3.
Two things occur during winterization and solvent removal, non-target constituents are removed from the extract and there is compounded loss from multiple pieces of process equipment. These steps increase the concentration of the d9-THC portion of the extract and produce two streams of noncompliant waste.
Decarboxylation & Devolatilization
Most cannabinoids in the plant material are in their acid form. For this exercise, 90% of the cannabinoids were considered to be acid forms. Decarboxylation is known to produce a mass difference of 87.7%, i.e. the neutral forms are 12.3% lighter than the acid forms. Heat was modeled as the primary driver and a process efficiency of 95% was used for the conversion rate during decarboxylation. To simplify the model, the remaining 5% acidic cannabinoids are presumed destroyed rather than degraded into other compounds because the portion of the cannabinoids which get destroyed versus degrade into other compounds varies from process to process.
Devolatilization is the process of removing low-molecular weight constituents from an extract to stabilize it prior to distillation. Since the molecular constituents of cannabis resin extracts vary from variety to variety and process to process, the extracts were assumed to consist of 10% volatile compounds. The model combines the decarboxylation and devolatilization steps to account for complete decarboxylation of the available acidic cannabinoids and ignores their weight contribution to the volatiles collected during devolatilization. Destroyed cannabinoids result in an amount of loss that can only be accounted for through a complete mass balance analysis. Data for decarboxylation and devolatilization are shown in Image 4.
As the extract moves along the process train, the d9-THC concentration continues to increase. Decarboxylation further complicates traceability because there is both a known mass difference associated with the process and an unknown mass difference that must be calculated and justified.
A two-pass distillation was modeled. On each pass a portion of the extract was removed to increase the cannabinoid concentration in the recovered material. Average data for distilled “hemp extracts” was used to ensure the model did not over- or underestimate the concentration of the cannabinoids in the distillate. The variables used to meet these data constraints were derived experimentally to match the model to the scenario described and are not indicative of an actual distillation. Data for distillation is shown in Image 5.
After distillation, the d9-THC concentration is shown to have increased by 874% from the original concentration in the plant material. Roughly 2.2 kg of the available 3 kg of d9-THC remains in the extract, but 0.8 kg of d9-THC has either ended up in a waste stream or walking out the door.
Chromatography – THC Remediation Step 1
Chromatography was modeled to remove the d9-THC from the extract. Because there are several systems with variable efficiency rates at being able to selectively isolate the d9-THC peak from the eluent stream, the model used a 5% cut-off on the front-end and tail-end of the peak, i.e. 5% of the material before the d9-THC peak and 5% of the material after the d9-THC peak is assumed to be collected along with the d9-THC. Data for chromatography is shown in Image 6.
After chromatography, a minimum of three products are produced, compliant “hemp extract”, d9-THC extract, and noncompliant residue remaining in the equipment. The d9-THC extract modeled contains 2.1 kg of the available 3 kg in the plant material, and is 35% d9-THC by weight, an increase of 1335% from the distillation step and 11664% from the plant material.
CBN Creation – THC Remediation Step 2
For this exercise, the d9-THC extract was converted into cannabinol (CBN) using heat rather than cyclized into d8-THC, but a similar model could be used to account for this scenario. The conversion rate of the cannabinoids into CBN through heat degradation alone is low. Therefore, the model assumes half of the available cannabinoids in the d9-THC extract are converted to CBN. The entirety of the remaining portion of the cannabinoids are assumed to convert to some form of degradant rather than a portion getting destroyed. Data for THC destruction is shown in Image 7.
Only after the CBN cyclization step has completed does the product that was the d9-THC extract become compliant and classifiable as a “hemp extract.”
Throughout the process, from initial extraction to the final d9-THC remediation step, loss occurs. Of the 3 kg of d9-THC available in the plant material only 2.1 kg was recovered and converted to CBN. 0.9 kg was either lost to the equipment, destroyed in the process, attributable to the mass difference associated with decarboxylation, or was never extracted from the plant material in the first place. All of these potential areas of product loss should be identified, and their diversion risk fully assessed. Not every waste stream poses a risk of diversion, but some do; having a plan in place to handle waste the DEA considers a controlled substance is essential. Without a track-n-trace program following the d9-THC and identifying the potential risk of diversion would be impossible. The point of this is not to instill fear, instead the intention is to shed light on a very real issue “hemp extract” producers and state regulators need to understand to protect themselves and their marketplace from the DEA.
Any brewmaster from the more than 7,000 U.S. craft breweries will tell you one of two things: That their art is a science, or that their science is an art. The answer might depend upon the brewer’s individual approach, but a combination of experience, process, precise measurement and intuition is exactly what’s required to create great beer. In a very similar way, the cannabis industry has its own version of the brewmaster: Extraction technicians.
A cannabis extraction technician deploys knowledge from multiple science disciplines to apply industrial solvents, heat and pressure to plant matter through a variety of methods with the aim to chemically extract pure compounds. Extraction techs use their passion for the cannabis and hemp plants, combined with chemistry, physics, phytobiology and chemical engineering to help create a result that’s not quite art, but not quite completely science. By manipulating plant materials, pressure, heat and other variables, the extraction technician crafts the building block for what will become an edible, tincture or extract.
Similarly, brewmasters use their knowledge of multiple science disciplines like chemistry and microbiology, as well as different brewing processes and a variety of ingredients to develop creative recipes that result in consistent, interesting beers. The brewmaster’s work is both science and art, as well. And they also manipulate plant materials, pressure, heat and other variables to achieve their desired results.
“I would certainly consider brewing to be an art and a science, but it takes a very disciplined approach to create consistent, yet ever evolving beers for today’s craft market,” says Marshall Ligare, PhD. Research Scientist at John I. Haas, a leading supplier of hops, hop products and brewing innovations. “We work to ensure brewers can create something different with every new beer, as well as something that helps create an experience as well as a feeling.”
In both brewing and extraction, the art comes in the subjective experience of the craftsman and his or her ability to curate the infinite possibilities inherent in each process. However, both are a science in their requirement of establishing production methodologies that guarantee a consistent, reliable product experience every time to win customer loyalty (and regulatory compliance). In the same way hops determine recipes for beer flavors, the cannabis plant determines extraction recipes, especially considering the role that terpenoids play in the quality, flavor and effects of the end product.
The development of new and appealing cannabis products is beginning to mimic the vast variety of craft beers now found all over the world. In the same way beer connoisseurs seek out the perfect stout, lager or IPA, discriminating cannabis consumers now search for that gem of a single-origin, specialty-strain vaporizer oil or irresistible dab extract.
“I see an exciting new day for quality-focused, craft extraction that tells a story, not only of where the cannabis plant might have been grown and how, but also the care that was taken in the processing of that strain into smokable or edible oil,” says John Lynch, Founder of TradeCraft. “Imagine the impact in the marketplace when product-makers figure out how to do seasonal one-offs where engaged connoisseurs are willing to pay a premium for the art behind limited releases.”
In either process, you’re essentially creating art with science. Each process works with different strains. Each is concerned with chemical and flavor profiles. Each has its own challenges. In both worlds, quality depends upon consistency. You’re creating art, but you need to replicate that art over and over – which can only occur with strict control of the process. Brewmasters seek control of things like yeast quantity and health, oxygen input, wort nutritional status and temperature, among other things. In their pursuit, extraction technicians seek to control temperature, pressure and flow rate–as well as all the ways these variables interact with each other. What enables this control in both efforts is the equipment used to achieve results.
“A modern brewhouse is very much like a scientific laboratory,” Ligare says. “Brewers treat their setup with the same care and attention a scientist gives to their lab equipment, and are equally concerned with precision, cleanliness and the purity of the result. With each new beer, they want to develop a process that can be controlled and replicated.”
The key to creating a precise process is to use instrument-grade extraction machinery that performs to specifications – and allows you to repeat the process again and again. The value of using high-quality instrumentation to manage and monitor either the brewing or extraction process cannot be overstated. Although it seems counterintuitive, this is where the “craft” comes into play for both brewing and cannabis extraction. Precise instrumentation is what allows the brewer or extraction “artist” to manipulate and monitor the conditions required to meet recipe standards. Along with the quality of the ingredients (hops, cannabis, hemp, etc.), the quality of the equipment utilized to create the product is one critical element impacting the end result. “Imagine the impact in the marketplace when product-makers figure out how to do seasonal one-offs where engaged connoisseurs are willing to pay a premium for the art behind limited releases.”
In cannabis extraction, a second crucial decision is determining which solvent is the best solution for the recipe you’re using and the end result you’re hoping to achieve. This decision is a part of the “craft” of extraction, and determined according to a combination of criteria. There’s no question that each solvent has a business case it serves best, and there is ongoingdebate about which approach is best. But overwhelmingly, the solvent that best serves the most business needs is CO2 due to its inherent versatility and ability to have its density tuned to target specific compounds.
“Control is what makes or breaks any craft product,” says Karen Devereux, Vice President of Northeast Kingdom Hemp. “We’re based in Vermont and love how Vermont is known for its quality craft beer, cheese and maple syrup. We wanted to bring that craft approach to hemp extraction, and everyone knows that any craft endeavor is focused on the details and getting them right again and again. You can’t do that without controlling every aspect of the process.”
Greater control of the process can also open up worlds of discovery. The inherent “tunability” of CO₂ enables the extraction technician to target specific compounds, enhancing the potential for experimentation and even whimsy. This can lead to entirely new products much in the way a brewer can control his process to create new, interesting beers.
American portrait photographer Richard Avedon famously declared that art is “about control,” describing the artistic process as “the encounter between control and the uncontrollable.” The same can be said for beer making and cannabis extraction. The more precisely you can control variables, the more options you’ll have for yourself and your customers. The more choices you’ll have with regard to different recipes and products. And the more loyalty you’ll ultimately generate among fans of your products.
Due to quick progressions in legalization, today’s cannabis industry bears little resemblance to the industry of five years ago. As the cannabis space gains mainstream acceptance, it resembles more “traditional” industries closely. In turn, how we consume cannabis has changed dramatically within this novel legal framework.
A brief visit to a cannabis dispensary quickly illuminates just how much the industry has changed in the past few years.
Within the dynamic of modern cannabis, perhaps no vertical has seen the same advancements as cannabis extracts. It’s precisely the growth of the concentrate category that has given rise to the many branded products that define the legal market.
To give a clear picture of how advancements in extraction have stimulated the concentrate category’s growth, we put together this brief exploration.
Standards & Technology
Before legalization, the production of cannabis extracts was a shady affair done in clandestine and often dangerous ways. Especially concerning BHO (Butane Hash Oil), home-based laboratories have long since been notorious fire hazards. Even more, with a total lack of regulation, black-market extracts are infamous for containing harmful impurities.
In the few short years that cannabis has been legal in Nevada, Washington and other states, extract producers have adopted standards and technology from more professional arenas. By borrowing from the food and pharmaceutical industries, concentrate companies have achieved excellence undreamed of a decade ago.
Good Manufacturing Practices
One of the essential elements in the extracts vertical advancements is the adoption of good manufacturing practices. According to the World Health Organization website, “Good Manufacturing Practice (GMP) is that part of quality assurance which ensures that products are consistently produced and controlled to the quality standards appropriate to their intended use.”
When adult-use cannabis was legalized in markets such as Colorado, cannabis companies were able to come out of the shadows and discuss GMPs with legit businesses. In doing so, they implemented professional controls on extract manufacturing in accordance with “quality standards” of state regulatory agencies.
Supercritical CO2 Extraction
As cannabis businesses adopted GMP from other industries, extract producers also embraced more sophisticated technology. Of these, supercritical CO2 has pushed the cannabis concentrates vertical into the future.
According to the equipment manufacturer Apeks Supercritical, “CO2 is considered to be a safer method of extraction because the solvent is non-volatile. The extract is purer because no trace of the solvent is left behind. It is also versatile and helps protect sensitive terpenes, by allowing cold separation.” By deriving methods from food production, supercritical equipment manufacturers have given cannabis companies a viable option for the commercial production of extracts.
Supercritical technology has helped push the concentrates vertical forward by providing a clean and efficient way to produce cannabis extracts. Nonetheless, supercritical CO2 equipment is highly sophisticated and carries a hefty price tag. Producers can expect to pay well over $100,000 for commercial supercritical CO2 extraction setup.
Just as standards and technology have evolved in the cannabis extracts vertical, we have also seen products rapidly mature. Notably, the legal environment has allowed manufacturers to exchange ideas and methods for the first time. In turn, this dialogue has led to the development of new products, like isolates and live resin.
Just as the name implies, isolates are concentrates made from a singular, pure cannabinoid. In today’s market, CBD isolates have grown increasingly popular because people can consume pure CBD without ingesting other cannabinoids or plant materials, including the legal 0.3% THC found in hemp.
Isolates are made by further purifying cannabis extracts in the process of purification, filtration and crystallization. As seen with other concentrates, isolates are used as the base for many cannabis products, such as gummies.
There is also growing interest in CBG isolate, which is another non-psychoactive cannabinoid when consumed orally.
The cannabis concentrate live resin has taken the industry by storm over the past few years. Live resin is a form of extract that is originally sourced from freshly harvested and frozen cannabis plants. The primary selling point behind this extract is the fact that fresh flowers produce much more vibrant aromas and flavors than dried cannabis. Interestingly, this pungency is tied to the preservation of terpenes in live resin.
To make live resin, producers “flash freeze” fresh cannabis plants immediately after harvest. Valuable cannabinoids and terpenes are then extracted from the fresh, frozen plant material using hydrocarbon solvents. This whole process is done at extremely cold temperatures, ensuring no thermal degradation to the precious and volatile terpenes.
In lieu of these intricate steps to preserve the flower and extracts, live resin has continuously gained popularity. Namely because vaping with live resin is the best way to sample fresh cannabis terpene profiles in its most authentic fashion
It is amazing to see how much cannabis extracts have grown and progressed with legalization. Due to such amazing advancements in standards, technology, and products, the concentrates category has exploded on the dispensary scene. In today’s market, flowers have been largely sidelined in favor of concentrate-based products like gummies. These products now adorn dispensary shelves in beautiful packaging replete with purity and testing specifications.
It’s an often-overlooked fact that the purity standards of the legal extracts have made reliable cannabis brands possible in the first place. You cannot develop a cannabis brand without consistent products that customers can rely on; all things considered, it can be said that advancements in extraction have not only stimulated the concentrate category but the entire industry as we know it today.
Carbon Dioxide (CO2) extraction is a processing technique whereby CO2 is pressurized under carefully controlled temperatures to enable extraction of terpenes, cannabinoids and other plant molecules.
Green Mill Supercritical is a Pittsburgh-based manufacturing and engineering company focused on cannabis and hemp extraction. The company offers a range of CO2 extraction equipment where users can tune and control their extraction methods.
We spoke with Wes Reynolds, CEO of Green Mill Supercritical. Wes recently joined Green Mill as CEO and investor in the company after a long career at the Coca-Cola Company in senior sales and general management roles.
Aaron Green: Wes, thank you for taking the time to chat today. How did you get involved in Green Mill?
Wes Reynolds: I came out of a 20-year career at Coca-Cola, where I lived and worked around the world. I was a sales and general management guy with Coke, and learned a lot about running businesses and how to drive growth. I left Coke in 2017. After that successful career I wanted to be in the cannabis space. I felt like cannabis was a growing space with a lot of opportunity and a lot of misperceptions out there, particularly around the foundations of what I would call the “evil reputation” of cannabis. I just found that abhorrent and wanted to be part of changing it.
So I ran the Florida operations for Surterra, which is now called Parallel, for a year out of Tampa, and we did a great job of growing that business in Florida. As the president of the Florida operation for Surterra, I saw everything seed-to-shelf for the industry. We had a 300,000-square-foot greenhouse in Central Florida, we had dispensaries, we had all the production, distribution and all the marketing. I was really able to learn the industry top to bottom.
When I left Surterra, I started looking at various investment opportunities and thinking about what I might want to do next. I came across Green Mill out of Pittsburgh, and was really impressed with the technology that they had put together. Having run a company where we used CO2 extraction, I had experiences with systems that didn’t work when they were supposed to or didn’t work the way they were promised, which led to lots of downtime, lots of frustration and lots of babysitting. I was impressed with Green Mill’s engineering approach and decided that I’d like to be involved with them. I originally considered just being an investor, but more and more conversations led to a greater understanding of some basic business administrative needs that they had as well. One thing led to another and I agreed to come on as the CEO, and I’m also an investor.
I’m excited about what we’re doing at Green Mill. I think that bar none, we make the best supercritical CO2 extraction equipment out there. We continue to innovate on that every day. We want to push CO2 beyond known limits, which is our stated goal as a company. We believe in CO2 and we’re living our goal in that we really are pushing it beyond known limits. There are new things we’re uncovering every day where we go, “Oh, my God, I didn’t know we can do that with CO2!” So, that’s kind of fun.
Aaron: Can you tell me just a high-level overview of how CO2 extraction works?
Wes: A supercritical CO2 extraction system is a collection of extraction vessels and fractionation vessels or collection vessels. In our case fractionation because we’re doing multiple collections through a single run. Then you need a system of pumps and valves and tubing, etc. to move the solvent in a supercritical state through the packed biomass, and then move the extracted compounds into a set of collection vessels. It sounds very easy. But the key to supercritical CO2 extraction is controlling temperature, flow rate and pressure. The better you can control temperature, flow rate and pressure, the more precise of an outcome you’re going to get. For example, say you run a three-hour extraction run, and you want to run it at 3500 psi. Well, you know, a competitive system might fluctuate 300 to 400 psi on either side of 3500. Whereas our system currently fluctuates more like five to 10 psi on either side of the 3500. So, there is much more control and precision.
Our whole goal, when we’re talking about pushing CO2 beyond known limits, is how do we continue to chase that holy grail of perfect control of temperature, flow rate and pressure? One of our advances so far is a proprietary pump, for example, that’s a liquid displacement pump that we engineer and build. It ensures a very even and consistent flow, independent of the pressure setting. So, that flow rate doesn’t change in our system compared to what you would see with another system. It sounds like a minor thing, except that at the end of a run, if you expected to get a certain set of molecules, you’re going to get a different set of molecules if your temperature and flow rate and pressure are varying, because what you’re doing is disrupting the density of the CO2 as it flows.
It’s about building a system that is precise in that way, I think, that requires enormously skilled engineering effort and design effort on the front end, and then requires us to have advanced production and manufacturing capabilities in our shop in Pittsburgh. Our customers are clearly impressed with the levels of consistency that they’re getting out of their system.
Aaron: You talked about precision and consistency as two items. Is there anything else that makes Green Mill different?
Wes: I’m a brand guy. I believe in brands. I came out of a 20-year Coca-Cola career.
The way that the cannabis industry is going in total, in my opinion, is the consumer is going to get more and more discerning along the way. Up until this point, everybody thinks “oh, we have THC and CBD and we have intensity.” But the more sophisticated and educated consumers get, the more discerning they’re going to be about what products they want to put in their bodies.
What makes Green Mill different is that we’re building a system that allows the operator of that system to create differentiated products for the marketplace. So, it’s not simply “CBD is CBD.” It’s: what plant did you start with? How can you maintain as many of the characteristics of that plant as possible?
We’re going to create the most sophisticated tool possible to allow the operator to create products that can be differentiated in the marketplace for a discerning consumer at a premium price. That way, you can create a market where there might not have been a market before, instead of just “hey, I’ve got X pounds of biomass that I need to extract. Give me your bluntest instrument and let me extract.”
We currently make five different systems. First is the SFE Pro. We make a seven and a half liter and a 10-liter version, with two-vessel configurations of each of those. Then we have what we call a Parallel Pro, which has four 10-liter vessels and two pumps, with two streams running parallel to each other and emptying into shared collectors. It doubles the extraction rate, and you don’t expand the footprint very much. But 10-liter vessels are the biggest vessels we use. Because when you go too large with the vessel, you are giving up something in terms of the ability to control temperature, flow rate and pressure. Your efficiency starts to drop with higher vessel volume.
One of the things that makes Green Mill different is our extraction rate. Our Parallel Pro can do 145 pounds a day of biomass. We think that’s a significant amount, given the demand that’s out there for unique products. What we’re advocating for is multiple extraction systems instead of giant permanent installations of extraction systems, that end up limiting your flexibility. Big systems also prevent you from creating redundancies in your operating system. So, when your extraction system goes down, you’re done. Versus in our universe, we would say, you might want to have three or four extraction systems in different locations, running different products. Our price points are such that that’s very doable.
Aaron: How does the breakdown look between your cannabis and hemp clients?
Wes: A lot of that is legislative frankly. It has to do with what the environment is like at the moment. About 60% of our customers are small hemp farmers. And then we have the other 40% in the cannabis space that are medical or adult use producers.
CO2 extraction has a lot of applications beyond cannabis. We have a couple of customers using our system for hops extraction, for example. We see an enormous opportunity out there for non-cannabis botanical extraction, but our primary focus is cannabis. That is what we’re designing this system to do.
We find that small hemp farmers love our system because it is reliable and very automated. We have proprietary software that operates the whole system. You load and run various “recipes,” at least we call them recipes. What you are doing is setting flow rate, setting temperatures, setting pressures, etc., then that proprietary software has an unbelievable ability to control everything through the process. I’ve talked to several different operators who have used other machines, and then found themselves on a Green Mill system and couldn’t believe how easy, but also feature-rich it was.
I talk about it like it’s like an oven, you know, you set the oven at 375 degrees. And a really good oven stays right at 375. You still need to be a good chef to be able to make that perfect cheesecake. But without that oven, your hands are tied, so you are constantly trying to check those, “is it still 375? I don’t know!” With our system, if it says 375, it holds at 375. So we’re pretty excited about that.
And we’re going to continue to innovate. For example, we have a proprietary heat exchanger that we use on our systems. It’s actually 3D printed stainless steel. It’s about a 20-pound piece of steel that’s been printed to have a special tubing shape in the center only possible with 3D printing that allows us to heat CO₂ very quickly.
Aaron: That’s very cool. I’m noticing a lot actually, the innovations in cannabis are creating these adjacent market opportunities in botanicals. So, I think that’s interesting you point that out. You mentioned terpenes are one of the things you collect out of the CO2 extraction. Can you talk about the crude that comes off and how people are either monetizing or formulating that crude?
Wes: Our goal is to produce the “purest crude” possible. So, we want “less crude” crude. I think that we’re at the beginning of this, Aaron. We’re nowhere near the end, which is what I find so exciting, because all of our innovation, all of our continued development and all of our experimentation is designed to keep thinking, how do we push this further and further and further and get a more refined crude.
We just welcomed Jesse Turner to our team as Director of R&D, who is a well-known extraction guy in the industry. He came from Charlotte’s Web and Willie’s Reserve, and has been doing independent consulting. He’s just a rock star. He’s already off and running on experimenting with different stuff.
I think that we are just at the beginning of seeing more and more of that opportunity to help people realize, “Oh, my gosh, I did not know you could do this!” Terpenes are a good example. I think we are only scratching the surface of what terpenes can do. I mean, a cannabis plant has 400 plus molecules and we know a good bit about probably 10 or 12 of them. So, what are we going to find out about the other 390? And as we do, the Green Mill system will be ideal for separating those molecules that we don’t know today are valuable. So, I think that’s part of what we’re chasing as well.
Aaron: So where do you see CO2 extraction fitting into the cannabis and hemp supply chain?
Wes: For any product on the market that is not a smokable flower it helps to have an extraction process. There may be some products that come out that we don’t know about yet that are not going to qualify in that category. Whether you are talking about vape cartridges, or lozenges, or gummy bears, or whatever it is, they are going to start with extract. I think what consumers want is zero adulteration of their product. So if you take any botanical product, and if it is GMO-free, does not have any pesticides, maybe it is all organic, etc. — there is real consumer appeal to that. Whether you agree with it or not, it is what consumers want.
We believe that we can continue to push CO2 so that there’s no requirement for introduction of any other materials than just CO2, which is a completely inert gas. It’s got no residual effect whatsoever on the product. If we get where we want to go, then eventually you are talking about a pure botanical experience.
Initial upfront capital is higher than you are going to see with ethanol and butane extraction solutions for the same size equipment, but ongoing operating costs of those are much higher, when you weigh it out over a period of time. I think what we are going to find is that people are going to keep coming to CO2 because they realize there are things they can do with it that they can’t do any other way.
The end consumer is really who we want to keep in mind. I think for a long time, this industry was very demand driven. “I have X acres of cannabis product, whether that’s hemp, sativa, indica, whatever it is, and I need to extract this many pounds a day over this period of time.” And we keep asking the question, well, who’s going to buy that product on the other side? What do you want it to look like when you put it out on the market? As opposed to how much raw plant matter do you have? What’s the demand? And that was a difficult conversation. We’re starting to see more people come around to that conversation now. But I think that’s the question we want to keep answering is how do we create those products that are differentiated in the marketplace and that can pass muster in any regulatory environment? People are going to want to know what’s in their product.
Aaron: What trends are you following in the industry?
Wes: As the CEO, I’m particularly interested in the overall development of the landscape of the industry in terms of who’s playing, who’s winning, what’s happening with legislation, MSOs versus SSOs. I’m also interested in the international environment. We have a good bit of interest from multiple countries that have either ordered Green Mill systems or are talking to us about Green Mill systems, including Canada and Latin American countries, some European countries, Australia and New Zealand.“We’re really committed to educational efforts with a very rigorous scientific foundation, but in language that is approachable and people can understand.”
The trends that I’m particularly interested in are more on the business side of the equation, in terms of how this business is going to shake out particularly from a capitalization perspective, as banking laws continue to change, which is a big deal, and the legislative environment gets a little more predictable and a little more consistent.
Aaron: Okay, last question. So what are you personally interested in learning more about?
Wes: Everything, is the short answer! I constantly run this little challenge of trying to understand enough of the science. I’m not a scientist, I’m a sales guy. That was how I grew up: general management and sales. I’ve made my living over many years being wowed by the pros. Depending on the scientists and the very specialized folks to help provide the right answers to things. I’m fascinated by the chemistry and I’m fascinated by the mechanical engineering challenges of what we do at Green Mill. So, I’m always interested in learning about that.
I think there’s a need, and it is helpful to be able to talk about those things in language that the layperson can understand, as opposed to explaining everything in scientific language. I think what I am trying to do is help people put it into a language that they can get, but that is not simple. Language that is correlative to reality. I think there’s so much misunderstanding about how these things work and what’s happening. We’re really committed to educational efforts with a very rigorous scientific foundation, but in language that is approachable and people can understand.
Aaron: Okay, that’s it. Thank you for your time Wes!
According to a press release, Drug Plastics & Glass, a packaging company that specializes in cannabis bottles and closures, announced new tools for their customers to calculate their carbon footprint. The company launched six new sustainability calculators with the goal to help their customers get more informed about their carbon footprint.
According to Jeff Johnson, director of marketing and business development for Drug Plastics, they want to show how small, incremental changes can have a lasting impact on a company’s environmental sustainability.“From switching to more eco-friendly resin and eliminating flame treatment, to calculating the savings gained from choosing PET plastic over glass, or eliminating collateral packaging, these calculators show how making simple changes can have a big impact on the environment,” says Johnson.
Here are some of their sustainability calculators they recently launched:
PCR PET Resin Sustainability Calculator: Reduce greenhouse gases by making new products from PCR PET removes plastic from the environment by converting PET plastic discarded by the consumer back into resin that can be used again.
Flaming Elimination Calculator: Conserve fossil fuels by opting out of the flame treatment process traditionally used to ensure water-based adhesive labels and silk screening would adhere properly to HDPE, LDPE, and PP bottles. Today, this is not always necessary.*
Bag Reduction Calculator: Determine the individual savings when you move to single bagging instead of double bagging bottles and closures inside the carton.
Concentrate Elimination Calculator: Switch from white pigmented bottles to those made with resin in its natural color state and eliminate CO2
Glass to PET Conversion Calculator: PET requires less energy to produce and saves on transportation costs.
Glass to HDPE Conversion Calculator: See the sustainable improvements in weight, transportation costs, and durability when you use HDPE instead of glass.
As cannabis markets continue to gain traction, inconsistent and largely unpredictable markets have left recreational consumers in an informational fog. Try as the industry may, or may not to inform consumers, the lack of knowledge was evident when an established Colorado hash company opened a second operation in California. Expecting high demand for their solventless concentrates, the demand for their solvent-based counterparts came as a surprise. Initially hoping to eliminate solvent extracts from their product line-up, the company was forced to devote about half their overall production to solvent extracts, until information spreads and attitudes start to change. Over the past year several companies have joined the solventless side of history, but consumer understanding remains largely stagnant. For those immediately overwhelmed by terminology, cannabis extracts, concentrates or hash are all interchangeable terms describing concentrated cannabis. Under these umbrella terms, two distinct categories emerge depending upon whether chemical solvents were or were not used to extract the hash. Hence: solvent or solventless. A brief overview of cannabis concentrates will help consumers to understand the evolution away from solvent extractions and toward a superior solventless future.
Before regulated cannabis markets, cannabis extracts had long been in use. These old-world methods of cannabis extraction use very basic solventless techniques to create more potent, concentrated forms of cannabis. Dry sifting is easily the oldest form of cannabis extraction and a prime example of one solventless technique. Something as simple as shaking dried cannabis over metal screens and collecting the residue underneath creates a solventless product called keif. Dark brown bubble-hash, made popular decades ago, is another ancient technique using only ice and water to perform extractions without chemical solvents. After decades of stagnant and limited old-world methods, changes in legislation allowed cannabis sciences to flourish. These old-world hash methods were quickly forgotten, replaced by the astonishing progress of modern solvent extractions.
The emergence of solvent extracts revolutionized cannabis around 2011, creating new categories of cannabis products that exploded onto the scene. Not only did solvent extracts produce the most potent and cleanest forms of hash ever seen at this point, it also created new possibilities for hash-oil vape cartridges and cannabis extract infused edibles. These solvent extracts use butane, propane, or other hydrocarbon solvents to extract, or “blast” cannabinoids from the plant. By running solvents through cannabis and then purging or removing leftover, residual solvents, a super-potent, premium hash product is achieved. Regulated markets require testing to ensure only a safe level, if any, of the solvent used in the extraction process remains in the final product. This technology ushered in the first wave of concentrates to medical and recreational markets under the descriptive titles of wax, shatter and crumble. While these effective and affordable products can still be found today, far superior products have largely replaced wax and shatter. Distillation techniques can further purify and isolate THC-a, while removing harmful residual solvents. For a time, Solvent-free was used to describe this ultra-purified distillate, but the needless term has fallen out of use. Solvent-free is still a solvent extraction using chemical solvents, don’t be fooled. Distillation and CO2 extractions have fallen into general disfavor as they destroy the flavorful terpenes and valuable cannabinoids, that when present create an “entourage effect.” This “entourage effect” happens when the medicinal and recreational properties are most effective, pronounced, and impactful due to a full range of terpenes and cannabinoids being present in the final product. With companies manually reintroducing terpenes to their final extracts, it’s an attempt to restore what was lost during solvent extraction processes. Many brands claim to use cannabis derived or food-grade terpenes to infuse or reintroduce terpenes into their purified hash oils. While this adds flavor and taste, especially to distillate cartridges, it’s far from an ideal solution. Armed with this new information, the informed consumer looks for a full profile of terpenes and cannabinoids in their hash.
With terpene preservation a new priority, all aspects of hash making were reevaluated. By using fresh-frozen cannabis flower, solvent extractions quickly reached new heights. Using the same techniques as prior solvent extractions, the cannabis plant is frozen immediately upon harvesting, rather than trimming and drying the crop as usual. Freezing the plant preserves valuable terpenes helping to create a new category for hydrocarbon extracts under the general label of live resins. This live resin, containing vastly greater profiles of terpenes and cannabinoids than earlier waxes, shatters or crumbles is sold as live-resin sauce, sugar, badder, frosting, diamonds and more. Many versions of live resin re-use previous terms that describe consistencies. These live resin solvent extracts outperform the wax, crumble and shatters of old, and are priced accordingly. Some of the best solvent extracts available today use butane to extract hash oil, which forms THC-a crystals and diamonds seen in live resin sauces. Having learned the value of terpenes and cannabinoids, early efforts to purify THC were clearly misled. The industry defining use of fresh-frozen cannabis flowers greatly improved the quality of all extracts having realized the psychoactive effects are largely dependent on the various profiles of cannabinoids and terpenes. Pure THC-a crystals and isolates are easily achieved with solvent extractions but, produce inferior effects both medicinally and recreationally. Discovering the “entourage effect” as described earlier, these elements of cannabis allowed old-world solventless techniques to be re-inspired and reinvigorated with the benefit of healthy genetics and a hearty understanding of past mistakes.
Having gone full circle, solventless techniques are again at the forefront of the cannabis industry, having attained near perfection for our current understanding of cannabis anatomy.
Using the lessons and tendencies of prior extractions, the solventless method, in all its final forms, begin with the same initial process to make ice-water hash oil. Often referred to as solventless hash oil (SHO), fresh-frozen flowers are submerged in ice and water, soaked and agitated before the water is filtered through mesh screens. As these mesh screens are measured by microns, the increasingly finer mesh works to separate and extract microscopic trichomes that break free from the cannabis plant. The 120- and 90-micron mesh screens usually collect pristine trichome heads. After scraping the remaining material from the screens, its sieved onto trays where the hash can dry using modern techniques of sublimation. The results are beyond phenomenal and are sure to shock even life-long cannabis consumers. This technique isolates only the most potent and psychoactive parts of the plant, to produce white to clear solventless ice water hash. When done with precision 6-star ice water hash is formed. The hash can be sold and consumed as is or undergo additional solventless techniques to produce hash-rosin. Not to be confused with live-resins, rosin uses pressure and slight heat to squeeze ice-water hash, into hash-rosin. Some companies have elected to whip their rosins into a solventless badder or allow their hash rosins to undergo a cold cure process that creates textures and varieties like hash rosin sauce. Regardless of the final solventless product, they all begin as ice water extractions. These simple, natural methods of extraction are quickly being adopted by companies known for live resin. As solventless extracts are safer, cleaner and superior in quality to solvent chemical extractions, the race is on as the industry shifts toward a solventless future.
While I’d be happy to never see another solvent extract again, without the miraculous breakthroughs and advances in all aspects of cannabis manufacturing and production we may have not yet arrived where we are today. When using solvents to extract, the trichomes, which contain the full spectrum of terpenes and cannabinoids, are dissolved by the solvent, which is then evaporated off, leaving behind dissolved trichomes. In solventless hash, these trichomes remain whole and are never dissolved or broken down. Instead they are broken free by agitation in ice and water, separating the trichome heads from their less-active stems. These valuable trichomes heads contain everything pertinent and are never destroyed, dissolved or melted like solvent-extractions are forced to do. The benefit of keeping the heads of these trichomes whole results in a far superior product expressing the full profile of terpenes and cannabinoids the way mother nature intended. This natural profile of trichomes lends itself directly to the entourage effect that solvent extracts were found to be missing.
Extraction techniques are not equal and depend upon whether quality or mass production is the aim. Solvent extracts have quickly begun to represent the old-guard of mass-produced cannabis concentrates, with the solventless new-guard focusing on quality, small batch, hash-rosin excellence.
Every detail counts at an indoor grow facility. Indoor growers have complete control over nearly every aspect of their crop, ranging from light intensity to air circulation. Among the most important factors to regulate is temperature. While ambient air temperature is critical, growers will also want to measure leaf surface temperature (LST).
To illustrate, let’s say you keep your living room at a cozy 76 degrees. Then, if you place a thermometer under your tongue – your body is (hopefully) not at 76 degrees but is likely between a healthy temperature of 97 to 99 degrees.
A similar story can be told for cannabis plants grown indoors. A grow facility’s ambient air is often different than the plants’ LST. Finding an ideal LST for plant growth can be complex, but modern technology, including spectrally tunable LED grow lights, can simplify monitoring and maintaining this critical aspect.
Why Should Growers Care About LST?
Temperature plays a pivotal role in plant health. Many biochemical reactions contributing to growth and survival only occur within an ideal temperature range. If temperatures dip or spike dramatically, growers may witness inhibited growth, plant stress or irreversible damage to their crops.
The leaf is among the most important plant structures as it’s where most metabolic processes happen. Therefore, finding an optimum LST can improve growth rate and the production of metabolites such as pigments, terpenes, resins and vitamins.
Because many plants rely on their leaves for survival, it makes sense that leaves have their own temperature regulation system. Evaporation through pores in the leaf – known as stomata – can cool the plant through a process called transpiration. Up to 90% of water absorbed is used for transpiration, while 10% is used for growth.
The efficacy of transpiration is determined by the vapor pressure deficit (VPD), which refers to the relative humidity in the ambient air compared to the relative humidity in the leaf. If relative humidity is low, the VPD can be too high, which may cause plants to have withered, leathery leaves and stunted growth. On the other hand, a low VPD correlates to high relative humidity, and can quickly result in disease and mineral deficiencies. Higher humidity often results in a higher LST as transpiration may not be as effective.
When it comes to LST, growers should follow these basic guidelines:
Most cannabis plants’ LST should fall between 72 and 86 degrees – generally warmer than the ambient air.
LST varies depending on individual cultivar. For example, plants that have evolved in colder climates can generally tolerate cooler temperatures. The same can be said for those evolved in equatorial or temperate climates.
CO2 availability also plays a role in LST; CO2 generally raises the target temperature for photosynthesis.
How Does Light Spectrum Affect LST?
We know that CO2 concentration, specific genetic markers and ambient temperature all play an important role in moderating LST. But another important factor at an indoor grow is light spectrum – especially for those using spectrally tunable LEDs. Growers will want to optimize their light spectrum to provide their crop with ideal conditions.
A combination of red and blue wavelengths is shown to have the greatest impact on photosynthesis and, thus, LST. Photons found along the green and yellow wavelengths may not be absorbed as efficiently and instead create heat.
Optimized light spectrums – those with an appropriate balance between red and blue light – create more chemical energy instead of heat, thereby resulting in a lower LST. Using fixtures that are not spectrally tuned for plant growth, on the other hand, can waste energy and ultimately contribute to a higher LST and ambient temperature, negatively affecting plant growth. Consequently, measuring LST doesn’t only indicate ideal growing conditions but also indirectly illustrates the efficiency of your grow lights.
LED fixtures already run at a lower temperature than other lighting technologies, so indoor growers may need to raise the ambient temperature at their grow facilities to maintain ideal LST. Switching to spectrally tuned LEDs may help growers cut down on cooling and dehumidifying costs, while simultaneously improving crop health and productivity.
What’s the Best Way to Measure LST?
There are several tools available for growers to measure LST, ranging from advanced probes to specialty cameras. However, many of these tools provide a reading at a specific point, rather than the whole leaf, leading to some inaccuracies. Temperature can dramatically vary across the leaf, depending if parts are fully exposed to the light or in the shadows.
Investing in a forward-looking infrared camera (FLIR) gives indoor growers a more accurate picture of LST and light efficiency. That being said, growers should not only measure leaves at the top of the plant, but across the middle and bottom of the plant as well. That way, growers receive a complete snapshot of growing conditions and can make changes as needed.
At an indoor grow facility, it’s not enough to only measure ambient room temperature. Of course, this aspect is important, but it will paint an incomplete picture of plant health. Measuring LST gives growers nuanced insights as to how plants respond to their environment and how they can better encourage resilient, healthy growth.
Using spectrally tunable LEDs makes achieving LST easier and more cost-effective. Lights with optimized spectrums for plant growth ensure no energy is wasted – resulting in superior performance and efficiency.
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