This method measures the roughness of paper and paperboard under conditions intended to simulate the contact pressures and backing materials used in the printing nip of letterpress, gravure and offset lithographic presses. The measuring principle, that of determining the resistance to flow or air between the test surface and a metal band in contact with it, is similar to that employed in TAPPI Test Method T 538 “Smoothness of Paper and Paperboard (Sheffield Method).” The major difference between this and other air leak methods is that the metal band dimensions, clamp pressures and composition of the measuring nip are all intended to simulate printing process conditions.
