Aluminum foil is produced by rolling sheet ingots cast from molten billet aluminum, then re-rolling on sheet and foil rolling mills to the desired thickness, or by continuously casting and cold rolling. To maintain a constant thickness in aluminum foil production, beta radiation is passed through the foil to a sensor on the other side. The foil is pliable, and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes laminated to other materials such as plastics or paper to make them more useful. Aluminum foil is widely used in packaging, insulation, electromagnetic shielding, cooking etc.