In medicine (traditional or herbal), a tincture is an alcoholic extract (e.g. of leaves, flowers, roots, seeds or other plant material) or solution of a non-volatile substance; (e.g. of iodine, mercurochrome).
Scientifically, to qualify as a tincture, the alcoholic extract is to have an ethanol percentage of at least 40-60% (80-120 proof) (sometimes a 90% (180 proof) pure liquid is even achieved). However, in herbal medicine, alcoholic tinctures are often made with various concentrations of ethanol, 25% being the most common. Other concentrations include 45% and 90%.
Herbal tinctures do not always use ethanol as a solvent, though this is the most frequent. Other solvents include vinegar, glycerol, ether and propylene glycol, not all of which are used (or suitable) for internal consumption. However, the advantage of ethanol is that being close to neutral pH, it is a good compromise as a solvent of both acidic and alkaline constituents.
Glycerine is a poorer solvent generally and vinegar, being relatively acidic, is a better solvent of alkaloids but a poorer solvent of acidic substances, which would result in the alkaloids being more active in the preparation than otherwise. However, for people who do not imbibe alcohol for medical, religious or moral reasons, non-alcoholic tinctures are a possible alternative.
Solutions of volatile substances were called spirits, although that name was also given to several other materials obtained by distillation, even when they did not include alcohol. In chemistry, a tincture is a solution that has alcohol as the solvent.
NB: pH is a measure of acidity or alkalinity of a substance.
Tinctures can be prepared as follows:
- Herbs are put in an appropriate container (glass jar etc.). Sometimes they are crushed or chopped to help the process along and a 40 proof spirit (80%) alcohol is added - a resonably good quality Vodka would be suitable.
- The jar is left to stand for 2–3 weeks, shaken occasionally, in order to maximise the concentration of the solution.
- The tincture can then be strained off into a sterile container.
Advantages of Tinctures
Ethanol is often able to dissolve substances which are less soluble in water, while at the same time the water content can dissolve the substances which are less soluble in ethanol. It is possible to vary the proportion of ethanol and water to produce tinctures with different qualities because of different substances it contains. One example of this is tincture of Calendula officinalis, which is frequently used either at 25% ethanol or 90% ethanol. The solvent (ethanol in this case) also acts as a preservative.
Ether and propylene glycol tinctures are not suitable for internal consumption and are instead used in such preparations as creams or ointments.