Why is my new cookware slightly raised in the center of the interior cooking surface? Is this a defect?
Good cookware has a concave base so that when it heats up and the metal expands, the base remains flat and steady on the burner. Even pans with stamped impressions need this feature. A concave base, not the stamped impressions, is the essential deterrent to warpage. It is a normal occurrence when this happens, and is not considered a defect.