Tween 61 is a wax-like ester designed for use in cementing, drilling, pipeline, production, refinery and stimulation. Tween 61 demonstrates excellent properties when working as an oil/water emulsifier, wetting agent and a cleaning agent. The Tween series of surfactants are polyoxyethylene derivatives of the Span series products. Tween surfactants are hydrophilic. Tween 61 is generally dispersible in water, and soluble in varying degrees inorganic liquids. Frequently, Tween 61 is combined with Span 61 to promote emulsion stability.