The Roughness of paper or similar material is defined as the volume of air that is forced by a specified pressure difference escapes in unit time by passing between the surface of the specimen and flat metal ring resting on a specimen. The values indicates the surface smoothness of graded paper suitable for good print quality.
A sample is placed on a perfect plane glass plate, measuring head on the test piece and a controlled and low air pressure pass through a flat metal ring and the specimen.
The pressure difference read off/on selected rota meter tube.
Measuring range: 5-150 ml/min. 50-500 ml/min., 300-3000 ml/min.