A tincture is usually an alcoholic extract of plant or animal material or solution using a low volatility substance likes iodine or mercurochrome. In herbal medicine, alcoholic tinctures are made with different amounts of ethanol, 25% being the most common. Some concentrations include 45% and 90%. Herbal tinctures are not always made using ethanol as the solvent. Other solvents include ether, vinegar, Glycerine, glycerol and propylene glycol. Ethanol has the advantage of being an excellent solvent for both acidic and basic (alkaline) constituents. Newer glycerite products are showing great promise, some even rivaling alcoholic tinctures. Tinctures are often called spirits, regardless of whether or not they contain any alcohol. Ethanol can break down substances which are less soluble in water, while at the same time the water content can dissolve the substances less soluble in ethanol. Alcohol acts as a preservative.