We have developed models to determine the radiative heat transfer of infrared dryers. Using the models, the efficiencies of several IR constructions are calculated. The radiation properties of all parts of the IR dryer are measured with an IT-IR spectrometer using integrating sphere techniques. With these models and measured results, the total efficiencies of several dryer constructions are calculated for: an electric dryer with a pambolic mirror, an elecmc dryer with a flat ceramic mirror, and a gas-fired dryer. The effect of a back reflector on these dryers is also calculated. The efficiencies of all these dryers are compared to each other.