Arithmetic Mean
Topographical metrics providing the arithmetic average of the absolute values of the profile height deviations from the mean line describe the texture of a substrate. Surface roughness ra is the most common parameter used in the paper and film industry to quantify finish. It is measured using a profilometer that moves a diamond stylus across the material surface to record the peaks and valleys.
Texture Measurement
Higher values indicate a more textured or matte finish that scatters light and feels rough to the touch when handled. Achieving a consistent surface roughness ra is essential for ensuring that ink spreads evenly and adheres properly to the surface. In flexible packaging, this property controls the friction between the film and the machine components which affects the tracking of the web.
Low values characterize glossy films that are prone to blocking and static issues in dry environments. The measurement process involves taking multiple readings across the web to ensure uniformity.
Print Interaction
Precision in this measurement allows manufacturers to meet strict specifications for high end graphics. Variations in surface roughness ra can lead to changes in perceived colour and gloss. It is a fundamental property for the calibration of printing presses.
