Abrading instrument, consisting of a horizontal turntable with a center clamp, which revolves at 70 to 75 rpm, upon which the specimen is attached, and two weighte parallel arms, each carrying a special abrasive embedded rubber whell, freely rotating on a ball-bearing horizontal spindle, and each resting on the specimen with a known dead weight load and an adjustable vacuum system for debris removal. For the dry paperboard test, 1000 gf or 500 gf is used with non resilient wheel. For the dry paper test, 500 gf or 250 gf is used with resilient wheels. For the wet test, 500 gf is used the same wheels as used in the dry tests. In all cases, the type and grit of wheels shall be agreed upon by user and supplier. The surface of the table is covered with a disk of soft rubberized material 0.762 mm (0.03 in.) thick each abrasive wheel is 44 to 51 mm (1 ¾ to 2 in). in diameter and 12.7 mm (1/2 in) thick and composed of a special finely screened and standardized abrasive. A revolution counter is attached to the table. The lines of contact of the wheels on the specimen are at right angles to the parallel supporting arms and situated 25 mm (1 in) from the center of the turntable towards the axis about which the supporting arms turn. The center of the line of contact of the wheel on the arm from which the turntable revolves is 31 mm (1 7/22 in) to the left. In this manner, where in contact with the turning specimen, the two wheels revolve in opposite directions and exert a combined abrasive, compressive, and twisting action over a circular path approximately 3000 mm2 (4.6 in2) in area, twice during each revolution of the specimen.
4.1.1 for the wet abrasion test, a rubber-covered turntable with an annular raised rim is used, to permit the surface of the specimen to be covered with water during the test. 4.2 Brush, soft brush about 12-13 mm (1/2 in) wide the bristles about 25 mm (1 in) long. Filter paper, sintered glass or Gooch cruicible, for wet abrasion residue. Resurfacing turntable, a rubber covered turnatable on which an abrasive disk is mounted, for resurfacing the wheels.