Crude Tall Oil (CTO) is a by-product of the kraft pulping process used by many paper mills. Tall oil soap is collected at the mills and then acidulated to make crude tall oil. It is a mixture of fatty acids, rosin and other neutral materials and forms water-in-oil emulsions and stabilizes mud systems at high bottom-hole temperatures. The CTO can then be further refined through the fractionation process to separate it into the components of tall oil fatty acid, tall oil rosin, distilled tall oil, pitch and heads. (GP-CTO)