The key to continuous casting is to catch the stream of molten metal as it falls from the tun dish (essentially a large, flat ceramic-lined pan) down into a square, water-cooled tube. As the metal touches the copper tube, the outside part cools, even though the interior remains liquid. Coming out of the tube the steel curves into a horizontal position and at that point is pinched into six to nine metre lengths of steel which then are cooled on large racks.