Processes for coating metal or polymeric substrates are provided which include the steps of: (a) applying a first powder coating composition to a surface of the substrate; (b) applying a first infrared radiation at a power density of 30 kilowatts per meter squared or less and optionally a first air simultaneously to the first coating composition for a first period of at least about 90 seconds such that a sintered first coating is formed upon the surface of the substrate; (c) applying a second powder coating composition over the first coating; and (d) applying a second infrared radiation at a power density of 30 kilowatts per meter squared or less and a second air at an air velocity ranging from about 0.5 to about 13 meters per second simultaneously to the second coating composition for a second period of at least about 2 minutes, such that a powder layered system is formed upon the surface of the substrate.