an automotive headliner comprised of a laminate of double corrugated paperboard . perforations in all the sheets of the laminate except the back paperboard sheet improve the acoustical performance of the liner . a vapor barrier on the back sheet prevents entry of moisture into the laminate from the roof , and a layer of sound dampening material on the front face of the laminate improves the sound absorption of the laminate . the front corrugation is larger than the back corrugation . when molding the laminate it is first moisturized , then heat molded . heat is applied until the laminate has regained its rigidity .