Abstract: A preheated workpiece having a surface with substantially arcuate curvature is supported by rotatable supporting means which has limited contact with said surface. Heat fusible plastic material in finely divided solid form is propelled against all parts of the surface of the workpiece, to be melted by its heat and fuse into an overall coating. During such coating, and thereafter until the material solidifies to substantial hardness, the supporting means is rotated, imparting rotation to the workpiece by its rolling contact therewith, and is cooled to maintain its temperature below the melting point of the material.