Abstract: The creation of a substantial volume of foam on the surface of an aqueous medium can reduce the apparent thermal IR emission substantially when compared to that of the aqueous medium free of foam. This difference in temperature (infrared emission) can be used to control a defoaming process or the addition of a defoaming agent to control foam in the aqueous medium. The apparent thermal infrared emission of foam is less than that of the aqueous medium. As the thermal IR emissions drop as foam develops, the difference between the apparent temperature of the foam and the temperature of aqueous medium increases. Such a difference in temperature can be used to control use of a defoaming process or agent. As the foam volume is reduced, the addition of a defoaming composition is substantially reduced or stopped. During the control method, a predetermined limit is established at which the defoaming process or composition is introduced into the aqueous medium.