An apparatus and method for evaporating a coating solvent from a coating on a first substrate surface of a substrate and for minimizing the formation of mottle as the coating solvent is evaporating. A drying oven includes an enclosure having an inlet and an outlet and defining a first drying zone. A plurality of drying subzones are within the first drying zone. At least two of the plurality of drying subzones employ different and controllable drying conditions. Physical barriers are not required to create the plurality of drying subzones.