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Solventless and Solvent Extraction: Basics, Benefits, Types

Supercritical CO2 extraction method
You may have heard the terms "solventless" and "solvent-free." Because the terms are similar, many assume that they mean the same thing - but this couldn’t be farther from the truth. There are important distinctions between solventless and solvent-free products.

There are many methods of extraction used in the cannabis industry today: hydrocarbons like butane and propane, alcohols like methanol and ethanol, supercritical CO2, and solventless elements like water and liquid nitrogen.

Solventless extraction

Solventless extraction is the natural, mechanical process of separating the trichomes from the plant material. For example, dry sifting marijuana through fine screens, cannabis flowers are rubbed against the fine mesh or sieve, breaking off the cannabinoid-rich trichomes that are collected below as kief. Through the application of heat and pressure, the powdery kief becomes a recognizable mass of hash — a solventless concentrate.

Solventless vs Solvent-free

The term solvent-free is most often used to describe products that meet a specific region’s regulatory threshold for residual solvents. While it strongly implies the product is 100% free of solvents, that’s not necessarily the case. Regardless of the type of extraction used in its production, every cannabis concentrate that’s sold in a licensed dispensary must be free of solvents.

Properly made solvent-based extracts have all of the solvents removed before being sold. This means that they can be labeled as solvent-free despite solvents being used in their manufacture. Solventless extracts on the other hand contain no solvents, and neither were any used in its production.
While the term solvent-free is valuable, being solventless is even more valuable to the segment of shoppers who don’t want to risk consuming any residual chemical solvents.

Dry sift hash

Dry Sift Hash is one of the simplest forms of hash to create. It requires minimal equipment and processing input, yet it has the potential to stand beside Bubble Hash as a quality solventless source material for rosin. Dry sift hash uses nothing more than some super fine micron screens and some elbow grease to separate the trichomes from the plant material. Cold buds are tossed back and forth across a fine mesh screen, which allows the trichomes to break off and fall through onto a surface below. The dry sift or “Kief” is then scraped together and pressed into blocks. But just because making Dry Sift Hash is simple, that doesn’t mean it’s necessarily easy. Especially if superior quality is your aim.

Ice water hash

Ice water extraction that creates bubble hash is a fairly recent addition to the solventless concentrate game. Ice water hash is made by putting cannabis in ice water, which freezes trichomes, and then agitating the mixture, which breaks off the trichomes. The mixture is then filtered through a series of mesh bags called “bubble bags,” which allow water and trichomes to pass through while holding back plant matter. Because trichomes are not water soluble, they are not dissolved like in solvent based methods. Instead, the cold temperature and gentle motion breaks the trichomes from the plant material, and thanks to trichomes being heavier than water, they sink. This makes them easy to collect in micron filter bags. Several bags are usually used with finer and finer meshes, refining the hash with each bag.

Rosin

The granddaddy of solventless concentrates is rosin. This simple method of applying heat and pressure to press out cannabis resins produces the cleanest concentrate there is. By not using any aggressive chemical assistance, rosin preserves more terpenes and cannabinoids than any other extraction method. The beauty of rosin is that it can be made from almost any starting material, be that dry sift or bubble hash, or even straight from cannabis flower itself. The process is simple, safe and requires no harmful chemicals to produce.

Live Rosin is a special form of the concentrate. Instead of using dried and cured bud, the marijuana flower is frozen immediately after harvest. This is a key differentiator due to the volatility of terpenes – some activate at such low temperatures, that even the change in temperature from harvest to drying can cause them to degrade in quantity.

Solvent extraction

The solvent-based extraction process uses chemical solvents such as propane, butane, carbon dioxide (CO2), and ethanol to strip cannabinoids and terpenes from the cannabis plant.
Properly made solvent-based extracts have all of the solvents removed before being sold and are removed the solvents to the level deemed acceptable by the country’s regulators.

Hydrocarbon Solvent

The utility of hydrocarbons tends to be the highest. The most popular solvent-based concentrates are almost certainly butane hash oil (BHO) and propane hash oil (PHO). With hydrocarbons, you can not only make high-quality artisanal extracts but also high-production or medium-high-production extracts as well. So if we’re going to make distillate or high-production shatter, or turn trim into an extract, hydrocarbons are a great option. It’s a heavy industrial process requiring closed-loop extraction machinery to produce safely, but the common availability of butane and propane makes it an accessible extraction method for small to large-scale producers.

CO2 Extraction

CO2 Essential Oil Extraction: 10 Most Frequently Asked Questions
CO2 extraction

Next up is Supercritical CO2 extraction, which is the method that creates the most oil for vape cartridges. It’s made using a high-temperature, high-pressure supercritical form of carbon dioxide as the solvent. The complicated nature of this extraction technique means you’ll need some seriously expensive high-tech equipment to pull it off. However, its low carbon footprint compared to hydrocarbon extraction and its more consistent results have made it a favorite in the commercial sector.

Alcohol

The oldest of old-school extraction techniques uses alcohol as a solvent. Ethanol or isopropyl alcohol takes the place of butane or CO2. Traditional hashes have been made this way for hundreds of years, but in more recent times, concentrates such as Rick Simpson Oil (RSO) are made using this method.

How To Remove Solvent from Extracts

Put the solvent extracts into a vacuum oven with a little bit of heat, and we purge the solvent.

Because the boiling point of butane and propane is very low, the solvent will boil right out of your product, leaving behind all your terpenes and cannabinoids, which are retained due to their heavy molecular weight. The light, volatile molecules of hydrocarbons are removed.

Which is better: Solventless vs Solvent Extraction

Whether you choose to dab or otherwise ingest solvent or solventless cannabis extracts is completely up to you. If you like to stick to pure cannabis products, you may prefer solventless extracts.

However, high-quality solvent dabs that have been properly purged offer a very unique experience that many cannabis enthusiasts love. Choosing one over the other will mainly come down to your own personal preferences and the availability of different extracts in your area.

Which one is better for business?

Lower barriers to entry are a big factor in making solventless extraction the most attractive option. Solventless extraction equipment typically costs a fraction of its more complex solvent-based counterparts. The solvent-based machines also require significant safety training to operate at extreme pressures with volatile materials that can spell disaster if not used properly.

In terms of return on investment (ROI), solventless concentrates are taking the lead thanks in part to a strong reassurance in products such as craft rosin. Some craft rosins are selling for over $100 per gram with intense consumer loyalty, ensuring very attractive margins even after you factor in a slower production time when compared with BHO products. Multiple runs with the same plant material that may otherwise be destined for disposal can also yield a variety of middle-grade rosins, kief, and edibles during second or third passes — “turning trim into gold” as the saying goes.

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