underfired

[W]hen the enamel is thick and a little underfired it will be lighter in color and have a pitted surface. Going further, extremely thick areas that are well underfired will be blistered, cracked, or bubbly.

Steak lovers want a charred surface and a rare, even cold, center. A high-tech overfired broiler is the secret. This kind of broiler delivers tremendous heat that is both predictable and consistent. Some establishments use the underfired version, which has the advantage of searing the bits of dripping fat, which gives the meat a barbequed taste. … The disadvantage of the underfired grill is the potential for flareups, which can cause a burned spot or carbonization. Not only do these taste bad, but they are also carcinogenic. Home grills are underfired; they must be watched carefully.