Microscopic Texture
Surface topography characteristics of this class describe the fine scale variations in the height of a paperboard surface that affect ink transfer and print quality. The surface micro-roughness determines the contact area between the printing plate and the substrate during the printing process. It directly affects the uniformity of ink coverage and the sharpness of the printed image.
Contact Sensor
Measurement of this property is achieved using air leakage methods or stylus profilometers that map the surface profile at a microscopic scale. A stylus with a fine tip is moved across the surface to record the height variations and calculate the average roughness. High roughness values indicate a surface with deep valleys and high peaks that require higher printing pressure and more ink to fill.
Low roughness values correspond to a smooth surface that allows for high resolution printing and consistent gloss.
Coating Demand
Achieving a smooth surface requires applying a coating of fine clay or calcium carbonate to the paperboard during the papermaking process. This treatment fills the valleys and creates a uniform surface that is ideal for high quality offset and flexographic printing. This measurement does not apply to highly absorbent or unfinished boards where the micro-scale variations are too large for precise stylus profiling.
Uniform roughness is essential for preventing mottle and inconsistent ink absorption.
