Weed Processors Are Fine-Tuning Cannabis Purity and Potency

In a rural warehouse in Brandon, bordered by greenhouses and fields, Tim Crossman dumped 30 pounds of freshly frozen cannabis flower into a stainless steel mixing vessel and filled it with ice water. Dressed in a head-to-toe clean-room suit and respirator mask, the 39-year-old head hash maker at Somewhere on the Mountain was combining an age-old hashish-making method with modern technology to create products that didn’t exist 20 years ago.

With the touch of a button, an industrial washer created a vortex of water that agitated the soggy buds, gently dislodging their trichome heads. The tiny, mushroomlike bulbs are the plant’s internal chemical factories, secreting the hundreds of terpenes and cannabinoids, including THC, that give cannabis its taste, smell and psychoactive properties.

The wash required a delicate balance of time and temperature. If Crossman agitated the mix too quickly, he would damage the heads and introduce contaminants, degrading the hash. Mixed for too long, the cell walls would deteriorate, releasing chlorophyll, which likewise adulterates the finished product.

Once the wash was complete, Crossman passed the mixture through ultrafine filtering bags, capturing just the trichome heads, which had the look and consistency of wet beach sand. They were then spread on trays, freeze-dried to remove the moisture and run through a press. The oil that oozed out, collected in Ball jars, would be used to make hash-rosin edibles, vape cartridges and other concentrates. No chemical solvents are involved in the process.

“We’re just getting the essence of that plant,” said Grant Jakubowski, 35, cofounder and co-owner of Somewhere on the Mountain, who’s been growing weed on this hillside since he was a teen. “The rest is going into our compost pile and back into our fields.”

Smoking weed is still the most popular way for Vermonters to get high: Of the more than 5,000 cannabis products licensed for sale as of June, more than half are flower or pre-rolled joints. (The Vermont Cannabis Control Board doesn’t track sales figures for individual product categories.)

But Crossman doesn’t wear the white bunny suit and respirator mask just to keep the products pure. He has asthma and is highly allergic to the cannabis plant and its smoke, but he still enjoys its effects. So the former chef of 15 years turned to consuming it in ways that didn’t trigger his allergies: by eating or vaping hash. He is not alone in wanting alternatives.

Concentrates are now Vermont’s second-largest category of cannabis products, according to Michael DiTomasso, director of compliance and enforcement for the Cannabis Control Board. Cannabis processors around Vermont are finding new methods for improving the plant’s potency, purity and delivery options, often by adapting technology from other fields.

Nationally, manufactured products in general — distillates, resin and rosin cartridges, and edibles — are the fastest-growing sectors of the adult-use market, according to BDSA, a cannabis industry data analytics firm in Colorado. (See sidebar for definitions of some frequently used terms.)

BDSA’s Katie Rizik highlighted in a March webinar some of the reasons consumers prefer such products: They’re more convenient, more discreet and easier to use.

Vaped products and edibles don’t carry the stigma associated with smoking, a plus for younger users whose stoner rites of passage didn’t necessarily include learning to roll a joint. Some medical marijuana patients cannot smoke, and consumers in general are becoming more health-conscious. Cannabis companies such as Somewhere on the Mountain have responded, offering new products that expand on the traditional ways to partake while still preserving the full spectrum of compounds found in the plant itself.

Granted, cannabis concentrates have their own stigmas to overcome. Some of the most potent varieties, such as the rock-candy-like shatter and diamonds, vaporize at higher temperatures. They’re often inhaled or “dabbed” using a glass pipe and a torch, a process that, to some, looks disturbingly similar to smoking crack cocaine. For this reason, many consumers prefer the more user-friendly dab rigs, electronic pipes that heat the concentrate to specific temperatures ranging from 400 to 650 degrees Fahrenheit.

More troubling than stigmas was news that shook the cannabis industry a few years ago: People were suddenly getting very sick, some even dying, after getting high on concentrates. In August 2019, the U.S. Centers for Disease Control and Prevention began investigating a steep rise in hospitalizations linked to respiratory problems such as coughing, chest pains and shortness of breath. Regardless of the patients’ age, geographic region or underlying health conditions, all had used vaping devices within three months of their illness.

The condition became known as “e-cigarette or vaping product use-associated lung injury” — EVALI for short. By February 2020, the CDC had documented more than 2,800 EVALI-related hospitalizations and 68 deaths.

Researchers later discovered that the main culprit in EVALI wasn’t the cannabis itself but the chemical vitamin E acetate, which some unscrupulous producers added as a filler. The vast majority of vape products linked to EVALI were purchased on the black market — which, unlike the regulated market, doesn’t routinely test for solvents, molds, heavy metals or pesticides.

When the Vermont legislature legalized the adult-use market, which opened in October 2022, it banned the use of some chemical solvents in extraction, including acetone and hexane. Other solvents are still permitted, such as butane, propane and ethanol, but a growing segment of Vermont processors forgo them in favor of more natural processes.

“I don’t know why we’d use a chemical that we then need to remove if we don’t have to,” said Nick Castro, cofounder, president and head of solventless production at Stone Leaf, a cannabis company in Windsor. Castro, 43, has worked in the cannabis industry for more than two decades, much of it as a legacy, or black market, grower.

Stone Leaf’s solventless hash rosin products include vape cartridges, gummies, taffies, tinctures and topicals. It also makes more niche products such as bubble hash and live rosin, which are concentrates that can be added to joints and smoked, or vaped in a dab rig.

The company recently released a new hops beverage called Hi-PA. The first hash-infused beverage sold in Vermont, it tastes like a citrusy India pale ale but contains 10 milligrams of solventless rosin and no alcohol.

Stone Leaf ships some of its hash rosin to the Northeast Kingdom for further high-tech processing in a nondescript warehouse off Route 15 in Hardwick, beside a maple syrup bottling plant and a beer keg storage facility. There, Eric Kawka and his partner, Doni Hoffman, operate a $600,000 laboratory that explores new ways of consuming cannabis. Their company, Tilia Processing, uses frozen plants and solvent-free hash rosin to make SpringTab, a fast-acting cannabis tablet.

Hoffman and Kawka, a natural products chemist, moved to Vermont from California in 2017 to open a lab at Waterbury’s PhytoScience Institute for medical marijuana patients. Later that year, the couple started their own research and development lab in Hardwick under the name Cattis, which for several years made CBD supplements. Because Kawka had experience making plant-based extracts for the nutraceutical industry, their pivot to hemp and then to cannabis was a natural progression.

Kawka specializes in an extraction process that uses carbon dioxide rather than chemical solvents. Though CO2 extraction is relatively new to Vermont’s cannabis industry, the technology has been used for years to decaffeinate coffee, make essential oils and sterilize medical devices.

“How can we keep pushing the boundaries of this technology?” Kawka asked rhetorically. “Being passionate about cannabis, it just made sense to marry the two.”

Kawka’s method is known as supercritical fluid extraction and purification. By manipulating CO2, heat and high pressure, he can select precisely which cannabinoids, terpenes, flavonoids and other compounds he wants to extract from organic matter, then harvest them into separate containers.

“No other technology gives us the selectivity that CO2 does,” Kawka said. “We completely deconstruct the plant and build it back up to preserve everything that’s in there.”

One section of the lab focuses solely on modeling how the human body breaks down those compounds in tablet form. A row of beakers mimics a stomach, combining heat and digestive acids, to measure how quickly SpringTabs dissolve and become bioavailable. For most users, it takes as little as 15 minutes — speedier than most edibles, which can take an hour or more. Kawka explained that the tablet’s rapid absorption helps prevent users from overconsuming while they wait for the effects to kick in.

SpringTabs hit the market two years ago after extensive review by the state’s Cannabis Control Board, which had no previous experience with cannabis in pill form.

“It took almost a year to get the product registered,” Hoffman recalled. “We were just sitting here twiddling our thumbs.”

Today, SpringTabs are available in about 30 dispensaries statewide in several varieties, including sativa-dominant, indica-dominant and hybrid forms, all of which come in easy-to-split 20-milligram tablets.

While cannabis tablets, rosin vape cartridges, and hash-infused beverages and gummies are all consumed in different ways, they share a fundamental characteristic: All are considered full-spectrum products, meaning that their chemical profiles are essentially identical to the plants from which they were derived.

While much of the industry focuses on producing high-potency THC-only distillates, full-spectrum products give the user the so-called “entourage effect”: the synergy of cannabinoids, terpenes, flavonoids and esters that gives each cannabis strain its unique character and complexity. Put another way, if a THC-only distillate is a solo guitarist, full-spectrum products bring the full band, including the horn section, percussionists and backup singers.

For the recreational user, the difference is readily apparent in the nature and duration of the high, which many people describe as more multifaceted and longer-lasting. And for the user seeking therapeutic properties, a full-spectrum product — sometimes referred to as “whole plant medicine” — could be key to relieving symptoms such as pain, seizures, insomnia, muscle spasms or gastrointestinal issues.

“I never use distillates. They give me a headache,” said Amelia Machia, co-owner of Apollo Legacy, a licensed cannabis cultivator in Berlin. Her company makes solventless-only products that “preserve the integrity of the plant,” she said. “That way you get that full spectrum of terpenes and cannabinoids that give the most full-bodied, beneficial effects.”

Machia, 29, should know. She has Ehlers-Danlos syndrome and Crohn’s disease and uses cannabis for symptom relief. As a budtender at Forbins Reserve dispensary in Barre and cofounder of the Green Mountain Patients Alliance, she routinely advises consumers whose doctors have recommended they quit smoking but who still want to treat their ailments with cannabis.

“That’s a good foray into ‘Here’s a slightly safer option where you can have a standard set dose for yourself,'” she said.

Full-spectrum products may offer another benefit: Diversifying the strains and methods of delivery could prevent users from developing a tolerance to the plant’s effects — or, at the very least, from getting bored with whatever they’re consuming.

Jakubowski at Somewhere on the Mountain, who grows cannabis using the same methods as organic farmers, hopes to bring to market what’s known as a full-melt hash: A specialty item for the cannabis connoisseur, he said, this concentrate delivers a flavorful and powerful punch every time.

“You can’t fake full melt,” he said with a sly smile. “It’s like going back to the first time you smoked weed.”

Deep in the Weeds: A Buyer’s Guide

The cannabis industry uses various terms to describe its products. While some are familiar (flower, pre-rolls, edibles) others are more obscure, even to the cannabis connoisseur — such as “sauce” and “diamonds,” both of which are concentrates new to the Vermont market.

For the uninitiated, “resin” refers to hash that is extracted using chemical solvents, whereas “rosin” is hash extracted using heat and pressure only. “Live” resin or rosin refers to products made from freshly frozen cannabis, whereas “cured” resin or rosin is made from the dried plant.

A “full-spectrum” product contains most, if not all, of the organic compounds found in the plant itself. A “distillate” typically refers to a THC-only product, usually a vape cartridge or “cart,” which contains few or none of the other cannabinoids or terpenes found in the whole plant.

Such distinctions can be confusing to consumers because the Cannabis Control Board has written no legal definitions for these terms as used in packaging and marketing. When in doubt, ask your budtender or processor.

Correction, July 18, 2025: An ealier version of this story mischaracterized how vitamin E acetate got into black market vape cartridges. Some producers deliberately added it as a filler.

This article appears in Jul 16-22, 2025.

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