Microwave-safe bags have been around for some time. They are a convenient and time-saving cooking tool, however, that’s where this method is limited and should never be used in a conventional or convection oven.

Consider: Microwave ovens cook food, using friction heat. Just the food absorbs the energy, so as long as the dish or container is microwave safe (i.e. glass or other non-metallic structure), then the food cooks as intended. Conventional or convection ovens cook by heating the air (and convection ovens heat and force-circulate the air) and the heat is absorbed in an outside-in manner, cooking the food. If a microwaveable bag were in the path of the conventional heat to the potatoes, the bag would end up being melted and charred. This is why something made to withstand and allow heat through and around is used, like a glass or ceramic container, or even a turkey roasting bag (made of a heat-resistant nylon or polyester) – something designed for such cooking. In short, physics dictates it’s all right to microwave in the so-designed potato bag, but that’s its limitation.