A fluid composition is prepared by esterification of (a) at least one synthetic alcohol and (b) a mixture of fatty acids, including at least oleic and linoleic acids, and at least one of a mixture comprising a Miristic acid, Palmitoleic acid, Margarinic acid, Margaroleic acid, α-Linoleic acid, Arachidic acid, Eicosenoic Behenic acid, and Erucic acid. The fatty acids can also include at least one of stearic acid and palmitic acid. The composition can be used as, or as part of, a quenching bath for a metal.