A tincture is typically an alcoholic extract of plant or animal material or solution of such or of a low volatility substance (such as iodine and mercurochrome). To qualify as an alcoholic tincture, the extract should have an ethanol percentage of at least 25–60% (50–120 US proof). Sometimes an alcohol concentration as high as 90% (180 US proof) is used in such a tincture. In herbal medicine, alcoholic tinctures are made with various ethanol concentrations, 25 eing the most common.