This test method describes the procedure for use of a hardness test hammer to evaluate the hardness of rolls of paperboard. When pressed against the surface of a roll of paperboard the hammer in this device is released from a calibrated spring. The hammer is caught on the rebound from the surface. The amount of rebound is indicative of the hardness at the point of impact. A rider on the scale of the instrument indicates the maximum rebound, hence, a measure of the roll hardness.