Cannabis concentrates are made by separating the plant’s active compounds (cannabinoids and terpenes) from the raw flower using either solvents, mechanical force, or a combination of both. The basic principle is always the same: isolate the resin-rich trichomes or dissolve the desired compounds out of the plant material, then refine the result into a potent final product. What varies is the method, and each one produces a different texture, potency, and flavor profile.
Solvent-Based Extraction
The most common commercial method uses hydrocarbon solvents, typically butane or a butane-propane blend, in a closed-loop system. The process works by chilling liquid butane to around -40°F (-40°C) and passing it through a column packed with cannabis flower. At that temperature, the solvent selectively pulls cannabinoids and terpenes from the plant while leaving behind most of the chlorophyll and other unwanted compounds. The cold temperatures are critical: they preserve the most volatile, flavor-carrying molecules that would break down under heat.
Once the solvent has washed through the plant material, it collects in a separate vessel along with the dissolved compounds. From there, the solvent is recovered and recycled back into the system using heating and cooling exchangers that manipulate temperature and pressure. Operators fine-tune the process by adjusting soak time, solvent blend ratios, and recovery temperatures to target specific compounds or textures. The end result can become shatter, wax, budder, or live resin depending on these variables and post-processing choices.
This entire process happens inside sealed, professional-grade equipment. The closed-loop design means the solvent never contacts open air, which is both a safety measure and a purity control. Open blasting (running butane through a tube into open air) is how concentrates were made in earlier years, but it’s dangerous and now illegal in regulated markets.
CO2 Extraction
Carbon dioxide extraction uses pressurized CO2 instead of hydrocarbons. When CO2 is pushed past its “supercritical” point, around 250 bar of pressure and 99°F (37°C), it enters a state that’s neither liquid nor gas and becomes an excellent solvent for plant oils. At that pressure and temperature, the CO2 reaches a density of about 894 kg/m³, dense enough to dissolve cannabinoids efficiently.
A typical supercritical CO2 run lasts about three hours. The pressurized CO2 flows through the plant material, strips out the target compounds, and then moves to a collection chamber where the pressure drops. As the pressure falls, the CO2 reverts to gas and evaporates, leaving behind a crude oil with no solvent residue. This is one of the method’s main selling points: the final product is inherently free of residual solvents because CO2 simply evaporates at normal atmospheric pressure.
CO2 extraction tends to produce a thicker, darker crude oil than hydrocarbon methods. It’s widely used for vape cartridge oil and edible-grade extracts, where a clean solvent profile matters more than preserving the full terpene spectrum.
Solventless Methods: Ice Water Hash
Solventless concentrates use only water, ice, heat, or pressure to separate trichomes from the plant. Ice water hash (also called bubble hash) is one of the oldest and most respected techniques. The process involves submerging cannabis in ice water and agitating it, which causes the frozen trichome heads to snap off the plant material. The mixture is then poured through a series of progressively finer mesh filter bags.
These bags are measured in microns. A typical eight-bag set ranges from 220 microns down to 25 microns. The top bags (220 and 190 microns) catch plant debris and ice. The magic happens in the middle: the 120-micron and 90-micron bags collect the most mature, highest-quality trichome heads with the best ratio of outer shell to internal oil. This is where “full-melt” hash comes from, concentrate pure enough to vaporize completely with no residue. The finer bags (73 microns and below) catch smaller, less mature trichomes and stalk fragments, producing lower-grade hash typically rated at one to two stars on a six-star quality scale.
Solventless Methods: Rosin Pressing
Rosin is made by applying heat and pressure to cannabis flower, hash, or kief until the resin oozes out. It’s the simplest extraction concept: squeeze hard enough and hot enough, and the oils separate from the solid plant material.
The ideal settings depend on the starting material. For flower, temperatures between 215°F and 230°F with 600 to 1,000 PSI of pressure work best. Hash and kief need gentler treatment: 170°F to 190°F at 300 to 800 PSI. Lower temperatures and longer press times (one to five minutes) produce a batter-like consistency with better terpene preservation, while higher temperatures yield a more sappy, translucent product with slightly less flavor complexity.
Rosin has become the foundation of the premium solventless market. Many high-end producers make ice water hash first, freeze-dry it, then press it into rosin. This two-step process, often called “hash rosin,” produces some of the most flavorful and expensive concentrates available.
Post-Extraction Refining
Raw extract straight from the machine is called crude oil, and it typically needs further refining before it becomes a finished product. The two most common refining steps are winterization and distillation.
Winterization removes fats, waxes, and lipids that were pulled from the plant along with the cannabinoids. The crude oil is dissolved in ethanol at 30 to 60°C using a ratio of about 10 milliliters of ethanol per gram of extract. The solution is then chilled in a freezer for at least 24 hours. As it cools, the fats and waxes become insoluble and precipitate out as solid particles, which are then filtered away. The ethanol is evaporated off, leaving behind a cleaner, more translucent oil.
Distillation takes refinement further by separating individual cannabinoids based on their boiling points. Short-path distillation uses a vacuum to lower boiling points, allowing cannabinoids to vaporize at much lower temperatures than they normally would. This protects them from heat degradation. The vaporized cannabinoids travel a short distance to a condenser (cooled to around 75°C in optimized setups), where they return to liquid form and are collected. The result is distillate: a clear, golden oil that’s typically 85 to 95% pure cannabinoid content.
Vacuum Purging for Solvent Removal
Any concentrate made with hydrocarbon solvents needs to be purged of residual solvent before it’s safe to consume. This happens in a vacuum oven, where thin slabs of extract are spread on trays and held at 85°F to 105°F under vacuum pressure. The vacuum lowers the boiling point of any trapped butane or propane, allowing it to escape from the extract at temperatures low enough to preserve terpenes and prevent the concentrate from degrading.
Purging can take anywhere from a few hours to several days depending on the thickness of the slab, the quality of the crude, and the equipment. Regulated markets test finished concentrates for residual solvent levels, and products must fall below established parts-per-million thresholds to be sold. The texture of the final product is partly determined during this stage: different purging temperatures and agitation techniques help create the distinction between shatter (stable, glass-like) and wax or budder (whipped, opaque).
How the Method Shapes the Product
The extraction method you choose determines more than just purity. Hydrocarbon extraction excels at capturing a full spectrum of terpenes, which is why live resin (made from fresh-frozen flower) has become so popular for its flavor. CO2 extraction produces a cleaner crude that’s ideal for distillate and vape oils but sacrifices some aromatic complexity. Solventless methods preserve the plant’s natural chemical profile most faithfully, since nothing is introduced that could alter or strip away delicate compounds.
Cost and scale also differ significantly. CO2 and hydrocarbon systems require expensive equipment and trained operators, making them suited to commercial production. Rosin presses range from affordable countertop units to industrial hydraulic setups, giving both home enthusiasts and commercial producers viable options. Ice water hash needs only bags, ice, and buckets at its simplest, though commercial operations use washing machines and freeze dryers to increase consistency and yield.