The Ultimate Cannabis Extraction Guide

An ancient technique

Solventless extraction methods do not use chemical solvents but heat, pressure, or ice water to separate the trichomes from the dried plant material.

Dry sifting on a basic level can be done in a cannabis grinder when the kief falls through the middle chamber to the bottom chamber. Commercial producers use a series of mesh screens and shake the dried material over them to break off and filter the trichomes (kief).

Ice water extraction involves submerging cannabis in a bucket lined with filter bags (bubble bags) and filled with ice water. The idea is to freeze and break off the trichomes by gently stirring the material. The trichomes are filtered through the bags and collected.

Rosin pressing involves compressing dried plant material to crush out the resinous oil. A similar process can be done using a simple hair straightener on the low setting and some parchment paper covering the nugs.

Solvent-based extraction occurs in a closed loop system using chemical solvents such as ethanol, hydrocarbons, and supercritical carbon dioxide. These methods require more safety precautions to protect against toxicity, fire, and explosions.

Hydrocarbons such as propane and butane are used due to their relatively low boiling point compared to other methods. This allows processors to extract more terpenes, which are known to have a lower boiling point than cannabinoids.

During the hydrocarbon extraction process, hydrocarbons are passed through the cannabis, dissolving the trichomes from the plant matter. The crude oil undergoes a vacuum purge to remove the residual solvent from the final extract.

Ethanol is generally used for high-volume hemp extraction. As a polar compound, ethanol can dissolve various compounds, including an excess of chlorophyll, which can create a bitter or harsh taste and requires further distillation to remove.

Ethanol extraction can be performed under warm or cold conditions. Warm temperatures can dissolve a greater range of cannabis compounds, good for full-spectrum extraction. Cryogenic (cold) extractions can reduce the fats and lipids in the extraction process, thereby reducing the need for winterization and streamlining high-volume production.

Supercritical carbon dioxide (CO2) is a state where this solvent acts like a liquid and a gas, diffusing throughout the dried material and dissolving the trichomes like a liquid. Supercritical CO2 is considered one of the most eco-friendly and safest extraction methods.

During this process, extractors pump the CO2 at high pressures and temperatures through the cannabis to dissolve the cannabinoids. A subcritical extraction uses lower temperatures and pressures to remove the terpenes and the cannabinoids at a higher temperature and pressure. Winterization using ethanol may be required to remove fats, lipids, and waxes.