Abstract: The present invention is directed to producing a smooth hard coating on a wood substrate. A layer of a foamed polymerized latex emulsion is applied on the surface of a wood substrate, such as an oriented strand board. The layer is dried, crushed and then cured to form the coating. If desired the cured coating may be provided with a post cure heat treatment to improve its hardness. The present invention is also directed to applying and drying the layer of the foamed polymerized latex emulsion on a mat of wood fibers or flakes and then crushing and curing the crushed layer and the mat into a hardboard having a smooth hard coating. The coating of the present invention is useful as a sealer coat on a wood substrate. By adding pigment to polymerized emulsion, the sealer coat can be used to provide a finish coat on the wood substrate.