Abstract: Multilayered sheet material, a method for producing said material and a package comprising said material are provided. The multilayered material and package produced therefrom have apertures sealed with an extrudable hot melt material which conveys moisture barrier properties and is adapted to soften and permit venting of vapor generated in the package prior to distortion of the package. The packages are adapted particularly for use as containers or as components thereof when used in heating or cooking of foods in microwave ovens.

Abstract: A carton is disclosed having a paperboard receptacle and a cover fitting over the same; the cover being adapted to shield the top and sides of food material within the receptacle from microwave radiation, but allowing radiation to be admitted through the unshielded bottom of the receptacle. A surface of the cover is formed of a conducting metal which substantially inhibits the passage of microwave radiation therethrough. The depending cover wall which surrounds the side edges of the receptacle is constructed such that adjacent portions of the panels forming the cover wall are provided with a low impedance electrical connection at microwave frequencies to inhibit arcing between such panels during heating.