CBD extraction methods
Supercritical CO2, ethanol, hydrocarbons, water vapor: comparison of the main methods of extracting CBD and hemp cannabinoids, their compromises.
CBD extraction methods
Extracting CBD (and other cannabinoids) from the hemp plant consists in separating the active molecules — concentrated in trichomes — from the rest of the plant matter. Several techniques coexist, with different tradeoffs in terms of purity, yield, cost, environmental footprint and preservation of terpenes.
1. Supercritical CO2 extraction (the standard)
The method considered state of the art by the artisanal industry.
Principle : CO2 placed under high pressure (~74 bar) and moderate temperature (~31 °C) becomes 'supercritical' — between liquid and gas. It acts as a selective solvent, extracting cannabinoids and terpenes without residue.
Pros :
- Inert non-toxic solvent
- No chemical residue
- Adjustable parameters for high selectivity
- Preserves heat-sensitive terpenes
Cons :
- Expensive equipment (≥ €100,000)
- Slow process
- Specific technical expertise
Favored by quality French producers.
2. Ethanol extraction
Principle : food-grade ethanol (drinkable alcohol) is used as a solvent. Cannabinoids and terpenes dissolve in it; ethanol is then evaporated, leaving the extract.
Pros :
- Less expensive equipment
- Good cannabinoid yield
- Recyclable solvent
Cons :
- Also extracts chlorophyll (greenish extract, bitter taste — requires refining)
- Partial terpene loss with heat
- Trace alcohol residues if poor purification
Common and acceptable method if mastered.
3. Hydrocarbon extraction (butane, propane — BHO/PHO)
Principle : light liquid hydrocarbons (butane, propane) dissolve cannabinoids and terpenes. The solvent is then evaporated.
Pros :
- Excellent terpene preservation (low temperature)
- Fast process, high yield
- Concentrates with marked organoleptic profile
Cons :
- Flammable hydrocarbons, explosion risk if amateur
- Heavy regulation in France
- Residual butane/propane traces if poor purification — health risk
Rather used for cannabis concentrates ('shatter', 'wax', 'live resin') than for mass CBD oil.
4. Steam distillation
Principle : steam passes through fresh plant matter and entrains volatile molecules. They are then recovered by condensation.
Pros :
- Simple inexpensive process (used since antiquity for essential oils)
- No chemical solvent
- Excellent for terpenes
Cons :
- Low cannabinoid yield (CBD poorly volatile)
- Quality compromise on cannabinoids
Rather used to extract hemp essential oils (pure terpenes) than CBD.
5. Mechanical extraction (ice water hash, rosin)
Principle : detaching trichomes by mechanical action (sieving, cold water, pressure + heat). The most ancestral methods.
- Ice water hash : agitation of plant matter in iced water, sieving — gives 'bubble hash'
- Rosin : pressing flowers or hash between two heated plates — gives a translucent extract
Pros :
- 100% solvent-free
- Preserves the integrity of the natural cannabinoid + terpene profile
- Increasingly recognized by artisanal industry
Cons :
- Lower yields
- More limited industrial scalability
Valued by artisanal producers for full-spectrum extracts.
Comparative summary table
| Method | Purity | Terpenes | Residues | Cost | Use | |---|---|---|---|---|---| | Supercritical CO2 | excellent | preserved | none | high | premium oils | | Ethanol | good | partial loss | possible traces | medium | wide oils | | Hydrocarbons | excellent | very preserved | high risk | medium | concentrates | | Steam distillation | low CBD | excellent | none | low | essential oils | | Mechanical (rosin/ice hash) | good | preserved | none | low | artisanal hashes |
How to know the method ?
A serious producer indicates the extraction method on the label or CoA. If the information is missing or vague, ask. The extraction method is part of artisanal traceability.