Abstract: A means and method for heat treating an upholstered workpiece such as a vehicle seat, including an enclosed cabinet mounting plural parallel-extending steam heated manifolds on either side of the workpiece as it passes between the manifolds. Unused steam is recirculated to a steam generator. By treating the entire surfaces of the workpiece, it is possible to eliminate the steaming of individually detected wrinkles, thereby saving both production time and associated manual labor. In an alternate method, the steam manifold is formed as an elongated loop and the workpiece is passed through an enclosed area formed by said loop as the upholstered part of the workpiece is unfolded upon a rigid frame.