Laser Line Triangulation Profilometry Principles on Continuous Paperboard Substrates
Inline blue laser triangulation measures paperboard surface topography at high speeds by overcoming fiber light penetration and isolating mechanical flutter.
Void Volume
Porous Architecture
Interstitial space within a fibrous network defines the structural potential of a paper sheet for fluid absorption. The void volume describes the fraction of the total sheet bulk not occupied by cellulose fibres or chemical fillers. Manufacturers derive this measurement by subtracting the apparent volume of the solid fibre material from the geometric bulk of the sheet.
High values correlate with enhanced ink receptivity and rapid liquid penetration in coating operations.
Fluid Dynamics
Hydraulic conductivity depends upon the interconnected nature of these air pockets throughout the web cross section. Dense fibre packing constricts these paths, causing potential flow resistance during the application of aqueous barrier coatings or high speed flexographic printing. A paper grade maintains a target pore structure to balance structural integrity against the requirement for controlled fluid uptake.
Variations in stock preparation or pressing stages during production alter the distribution of these cavities. Precise control over the interstitial matrix prevents coating strike through while ensuring adequate anchoring of adhesive layers.
Physical Measurement
Porosimetry techniques quantify these internal spaces by forcing a non-wetting liquid into the structure under increasing pressure. Helium pycnometry offers a method to determine the skeletal density of the material by displacement. Calculating the difference between the geometric density of the sample and the measured skeletal density yields the proportional empty space.
Calibration of these analytical instruments relies upon reference samples with known pore architectures to ensure consistent results across different laboratory environments. The measured capacity for air or liquid retention dictates the operational limits of a substrate during complex converting processes.