Abstract: An improved microwave energy moderating cooking bag for enclosing, for instance, a food stuff such as a beef roast so that it can be cooked at a relatively high, constant level of power in a microwave energy field (eg; in a microwave oven) to a predetermined degree of doneness without needing to periodically reposition the roast to achieve uniform doneness. The improved bag is of the type having microwave enery moderating wall portions which comprise perforated electrically conductive sheet material: for example, aluminum foil.The bag is improved by virtue of having adjacent side-by-side segments of the perimetrical edges of the electrically conductive sheet material sufficiently offset with respect to each other to virtually obviate edge-to-edge electric field relations. That is, sufficiently offset to precipitate edge-to-surface electric field relations as opposed to edge-to-edge electric field relations.

Abstract: An improved microwave energy moderating bag for enclosing, for instance, foodstuff such as a beef roast to be cooked at relatively high power in a microwave oven so that the foodstuff can be uniformly cooked to a predetermined degree of doneness without being repositioned and without having to vary the power level during the cooking interval. The improved bag is of the type fabricated from a laminated sheet comprising two laminae of thermoplastic films and a perforated foil lamina of microwave reflective material such as, for example, aluminum foil. The improved bag comprises an improved pouch-type top closure and duplex side seams. Both static and dynamic embodiments of the invention are disclosed: a static embodiment being dimensionally stable as opposed to a dynamic embodiment which is heat shrinkable by virtue of comprising a heat shrinkable thermoplastic film.