A method is disclosed method for manufacturing a cardboard product comprised of at least two layers, the method comprising the step of bonding the separate webs of paper or cardboard by an adhesive into a combination product. At least one of the webs is worked mechanically by embossing so that the permanent deformations appear projecting outwardly from at least one surface of said at least one web to a height not making the web thickness to exceed 3 mm. The method is further applicable to the manufacture of a cellulosic-fiber-containing cardboard or paper product for manufacturing a multilayer cardboard grade comprising at least two adhesively bonded layers, whereby the product is worked mechanically so as to make permanent three-dimensional deformations on the product material to a height not making the product thickness to exceed 3 mm.