Cannabis Extraction Methods: Overview of Techniques

Cannabis extraction is the process of separating desired compounds—primarily cannabinoids and terpenes—from the plant material to create concentrated products. These extracts are used in vapes, edibles, tinctures, and topical applications. The choice of solvent and method significantly influences the purity, potency, and profile of the final product.

I. Solvent-Based Extractions

Solvent-based methods use a chemical substance to dissolve and strip the desirable compounds from the cannabis biomass.

A. Butane Hash Oil (BHO) and Propane Hash Oil (PHO)

These methods use light hydrocarbons (butane or propane) as the primary solvent. They are highly efficient at extracting the full spectrum of cannabinoids and terpenes but require specialized equipment and safety protocols due to the volatile nature of the solvents.

Method	Solvent Used	Primary Product Form	Key Characteristic
BHO	Butane	Shatter, Wax, Crumble	High yield, efficient at low temps
PHO	Propane	Budder, Sap	Often purer than BHO, lower boiling point

B. Ethanol Extraction

Ethanol (grain alcohol) is a polar solvent that can extract cannabinoids efficiently. It is generally safer to handle than hydrocarbons but can also pull undesirable compounds, such as chlorophyll, which can affect the taste and color of the final extract.

• Warm Ethanol: Fast and efficient, but increases the co-extraction of chlorophyll.
• Cold Ethanol (Cryogenic): Used to minimize the extraction of chlorophyll and waxes, resulting in a cleaner, lighter-colored oil.

C. Isopropyl Alcohol (IPA) Extraction

IPA is sometimes used as a solvent due to its accessibility. However, it requires careful purging and is generally less favored in commercial operations due to potential toxicity risks if not fully removed.

II. Non-Solvent (Mechanical) Extractions

These methods use heat and/or pressure to separate the cannabis compounds without the use of chemical solvents.

A. Rosin

Rosin extraction is a popular, solventless method that uses heat and pressure to squeeze the oil from the plant material. The quality is highly dependent on the starting material.

Starting Material	Process	Typical Result	Notes
Flower/Buds	Heat and pressure applied	Rosin concentrate	Best for small-scale operations
Bubble Hash/Kief	Lower heat, pressure applied	Live Rosin	High-quality, full-melt product

B. Ice Water Hash (Bubble Hash)

This technique uses ice water and agitation to separate the trichomes (resin glands containing cannabinoids and terpenes) from the plant material. The mixture is then filtered through a series of progressively finer mesh bags ("bubble bags") to grade the product.

• The final product is a clean, solvent-free concentrate.
• The highest quality product is often referred to as "full melt" and is suitable for dabbing.

III. Supercritical CO2 Extraction

Supercritical CO2 extraction uses carbon dioxide under high pressure and controlled temperature. In its "supercritical" state, CO2 behaves as both a liquid and a gas, allowing it to function as a highly tunable solvent.

• Tunability: Adjusting the pressure and temperature allows operators to target specific compounds. Low pressure/low temperature may target terpenes, while high pressure/high temperature targets cannabinoids.
• Safety: CO2 is non-toxic and non-flammable. Once the extraction is complete, the CO2 simply turns back into a gas and is recycled or vented, leaving no residual solvent.
• Product Range: This method can produce highly pure oils suitable for vapes, edibles, and medical applications.

IV. Comparison of Extraction Methods

The table below summarizes the key trade-offs between the primary commercial methods.

Method	Safety/Hazard	Solvent Residue	Flavor/Terpene Preservation	Equipment Cost
BHO/PHO	High Hazard	Requires careful purging	Excellent (Full Spectrum)	Moderate
Ethanol	Low Hazard	Minimal/Low	Moderate (can pull chlorophyll)	Moderate
Supercritical CO2	Very Low Hazard	None (reverts to gas)	Good to Excellent (Tunable)	High
Rosin (Mechanical)	None	None	Excellent	Low to Moderate