Three-Dimensional Topography
Metrological quantification of three-dimensional topography maps height variations across a defined spatial region rather than along a single line. In paperboard characterization, areal surface texture establishes parameter sets such as Sa and Sq to describe peak distributions, void spaces and surface amplitude across a sample area. Standard profile measurements miss directional defects, whereas spatial mapping captures localized coating voids and fiber topography.
Roughness Evaluation
Non-contact optical instruments capture height fields without deforming soft coating layers or compressible fiber matrices. Interferometry and confocal microscopy gather millions of data points across paperboard surfaces, forming digital elevation models that reveal structural defects. These surface maps quantify peak density and core roughness, parameters that dictate how coating formulations settle into sheet valleys.
Optical measurements provide clear data across wide fields of view, ensuring that local defects are isolated before printing. High areal surface texture values correlate with uneven ink absorption and loss of printed gloss, making spatial characterization essential for premium packaging stocks.
Printability Impact
Ink transfer efficiency on high-speed presses depends on contact area between print plates and substrate peaks. Excessive surface roughness leaves deep valleys unfilled, creating pinholes and broken halftone dots in printed images. Surface smoothing treatments such as calendering reduce spatial height variations to ensure uniform ink film thickness across the packaging board.
