Polyester-40 is a copolymer that is formed by the condensation of hydrogenated dimer acids and hydrogenated dimer alcohols. The copolymer is capped with Stearic Acid (q.v.). The hydrogenated dimer acids are made from Rapeseed Acid by reacting the unsaturated fatty acids followed by hydrogenation. The dimer alcohols are produced by reducing the acid groups on the hydrogenated dimer acids to convert them to hydroxyl groups.