A type of organic acid derived from animal and vegetable fats and oils. Fatty acids are the raw materials used in the manufacture of many drilling-fluid additives, such as emulsifiers, oil-wetting agents and lubricants. Tall-oil fatty acids are distilled from conifer trees. Animal and vegetable fats and oils are triglycerides, which are hydrolyzed to give fatty acids (and glycerol). Fatty acids from animals are mostly saturated acids, having single bonds between carbon atoms. Tall oils and vegetable oils yield both saturated and unsaturated (double- and triple-bond) fatty acids.