Cannabis in Oil – The Methods Compared

Two processes make an oil extract strong. The acid has to convert, and the compound has to move into the fat. Both happen at similar temperatures yet follow different rules, and most instructions cover only one of them reliably. Anyone trying to improve a result should therefore first work out which of the two is failing.

The two steps

Conversion depends on temperature and time and happens inside the material itself; it is covered in the article on decarboxylation. The move into the fat is diffusion, and it depends on contact area, particle size, the ratio of plant to fat, and again on time. Fully converted flower that spent too little time in the fat yields a weak oil. A long infusion, conversely, achieves little if the acid is still largely unconverted.

Oven, short and hot

The only directly measured condition for complete conversion of the main acids is thirty minutes at 145 °C. Little cannabinol formed under those conditions, but the terpenes were almost entirely gone afterwards: only traces of the monoterpenes remained detectable. Anyone taking this route should spread the material thin rather than heap it, and cover the vessel, because open airflow creates exactly the losses that are avoidable.

The jar in a water bath

Flower and oil in a jar, the jar in boiling water, one to two hours at around 98 °C: this is a published method, used in pharmacies, and of all the routes tested it preserves the most terpenes. It converts only a small share of the acid, however. In the study describing the protocol, 5 to 10 % of the total content was present in the active form after two hours. For a terpene-rich preparation that is a deliberate trade. For maximum potency it is not.

Long simmering in fat

The kitchen classic keeps the material under fat rather than in air, closing the two loss routes that make an open oven expensive. Over several hours at 95 to 100 °C it handles both steps in one pass. At what total time conversion becomes practically complete has not been measured, and the available figures contradict each other: rate constants from oven trials predict a far advanced conversion after two hours, while the measurement on the oil extract does not show it. The cautious route is therefore to combine the short hot pre-step with the long gentle infusion.

Choice of fat

Olive oil has been measured directly as a carrier for cannabinoids and terpenes, and is recommended as cheap, non-flammable and non-toxic. Its drawback is that an oil extract cannot be concentrated by evaporation, so more of it has to be consumed. Coconut oil and butter are widespread, but no robust yield comparison between fats exists for kitchen conditions. Activated charcoal filtration, sometimes suggested for removing colour, also strips around half the cannabinoids from an ethanol extract and is explicitly not recommended. Naphtha and petroleum ether should be avoided, since measurable hydrocarbon residues remain in the extract.

Water and shelf life

A splash of water caps the temperature in the pot at 100 °C and prevents local overheating. Whether it raises potency has not been measured. The other side is well documented: if water stays in the finished extract, the oil becomes a perishable food. Oil is low in oxygen and low in acid, which is the environment in which spores can germinate, and food safety guidance on herb oils without an acidification step calls for refrigeration and use within a few days. The water therefore belongs separated off after simmering rather than stored along with the oil. What an emulsifier changes about this, and what it does not, is covered in the entry on lecithin.