Method and apparatus for applying a secondary layer or coating on surfaces of wet formed board materials are disclosed. The secondary layer is applied to the wet mat material of the board being manufactured during press rolling of the wet mat. The secondary layer material is supplied in the form of a slurry which is caused to adhere to the surface of a wire screen. The wire screen surface bearing the layer of slurry material is then pressed onto the mat surface to deposit the slurry layer thereon.