Singlefacer corrugator rolls are very important components in the corrugating process. They produce the fluted medium which is the foundation on which the quality of corrugated board is based. If the condition of the corrugator rolls is allowed to deteriorate, board quality and corrugator productivity will deteriorate with it. Corrugator rolls are hollow steel cylinders, with gearlike teeth (or flutes) machined onto the surface. The entire surface is overlaid with a layer of chrome, which protects the underlying steel flutes from wear. During the running life of a corrugator roll, wear caused by friction from the corrugating medium gradually wears away the chrome overlay, thus exposing the machined steel teeth underneath to wear. If the base metal is allowed to wear without recovering it with fresh chrome, a noticeable drop in flute height (caliper) will occur, and high-lows (a condition whereby flutes are not of uniform height exiting the corrugator rolls) will become more pronounced. The corrugating roll will have to be recut, rebuilt to original specifications, or even scrapped. A simple test, called the Copper Sulfate Test, can be run to determine the condition of corrugator rolls.