Abstract: A method and an apparatus for forming a coating layer on a molded product formed in a split-type mold assembly, which assembly includes first and second dies supported for movement relative to each other and a shut-off pin for forming a perforation in the molded product. The shut-off pin is first caused to project into a mold cavity, defined between the first and second dies when the both are closed together, through the first dies during the formation of the molded product. The shut-off pin is then allowed to retract from the mold cavity and inwardly of the first dies, leaving in the molded product the perforation extending completely through the thickness of the molded product.

Abstract: An in-mold coating apparatus which comprises movable and fixed molds which when mated together defines a molding cavity, and an injector assembly for injecting a plasticized coating material into the molding cavity to form a coated layer on a primary molded product within the molding cavity. The movable mold has an opened position at which the complete molded product with the coated layer thereon can be removed out of the molding cavity, a first closed position at which the primary molded product can be formed and a second closed position at which a space is formed between the movable mold and the primary molded product for the formation of the coated layer. The injector assembly has a tubular rod having one end adapted to selectively close and open an injection opening, and also having an air passage defined therein for the application of a blast of compressed air into the space to urge the primary molded product against the fixed mold.

Abstract: Impregnant including surfactant to an amount to bring the surface tension of the impregnant to a value which permits impregnation of a part by the impregnant to be effected under conditions of normal pressure and temperature, whereby the impregnation process is simple and expensive equipment is unnecessary.