Phytochemicals are naturally occurring compounds found in plants, and have been extracted into ethyl alcohol for use as medicinal remedies for a very long time. This is because many of the ingredients in plants are highly soluble in alcohol and easily extracted, including terpenoids and cannabinoids, flavonoids, and other essential oils. These compounds are mostly hydrophobic (they dislike water), and are often degraded in acid solutions such as black tea and vinegar.
Most alcoholic herbal tinctures contain between 25% – 65% alcohol, depending on the requirements of the ingredients. Often the alcohol is referred to as “grape spirits.” The best example of medicinal grape spirits is brandy, which is still available today in medicinal grade. A good example is Rescue Remedy, which contains 27% grape spirits. However, cannabinoids are only significantly soluble in more concentrated ethanol solutions – mainly those greater than 75% (150 proof) and ideally even 95% (190 proof).
Tinctures made with alcohol are generally better preserved than other types of tinctures, due to the antibacterial nature of alcohol. Many essential oils also have antibacterial and anti-fungal properties as well; thus, when added into an alcoholic tincture, they tend to be very stable and reliable over a long period of time, with or without refrigeration.
Inclusion of alcohol into a tincture usually does not cause problems since the dosage of alcohol is rarely more than half a milliliter (approximately 10 drops). If the tincture can be boiled down to concentrate it, even less alcohol will be delivered per dose.
A simple extraction with 10 grams of decent quality cannabis flowers (typically containing ~20% total cannabinoids by weight) mixed with ~100 mL of 75-95% ethanol (150 Proof to 190 Proof) will yield a tincture in the 20 mg per milliliter dosage range. It can be further concentrated by evaporating it down to be between 100mg – 300mg/mL (boiling for many hours will decarboxylate a small fraction of the acid cannabinoids into neutrals, but most will not react). Warning: Ethanol is highly flammable, especially when heated; any open source of flame or spark can easily ignite ethanol vapors, causing fire and potentially serious injury from burns. Do not heat ethanol on a gas stove or in the presence of any spark source.
Extraction of heated (decarboxylated) cannabis results in less chlorophyll content. Extracting unheated cannabis results in a non-psychoactive tincture of anti-inflammatory properties such as pain relief for those with arthritis and other anti-inflammatory conditions.
The greater the water content in the alcohol, the less solubility the alcohol will have for the essential oils. A tincture being extracted in 75% alcohol – 25% water – extracts the terpenoids (including cannabinoids) more slowly than 95% alcohol can.
Cuticle waxes make up about 20% of the content extracted into 95% alcohol. Once extracted, diluting the alcohol with water down to 80% alcohol, almost all of the waxes can be dropped out, leaving the terpenoids still in solution and therefore producing a cleaner product. When you hear about a cannabis product being “very dirty,” it is often because the waxes, chlorophyll and other undesirable impurities have not been removed.