A method and apparatus of powder coating relatively large objects such as automotive or other vehicle bodies comprises a spray booth having an interior which includes a cut-in coating zone having a relatively large area to permit the application of powder onto the interior portions of the vehicle body such as the inner door flanges, a side coating zone area wherein the vertically oriented, exterior surfaces of the vehicle body are coated such as the doors and fenders, an overhead coating zone in which the horizontally oriented, exterior surfaces of the vehicle body are coated such as the hood, roof and trunk, and, two transition zones separating the three coating zones. Air infeed and exhaust devices associated with each coating zone and each transition zone are operated to vary the air flow rate within the booth interior in the course of movement of the vehicle body therethrough such that the air velocity in each coating zone is maintained below a predetermined maximum downdraft velocity throughout the coating operation, and such that a slightly negative pressure is maintained within the booth interior.