Virgin SBS against White Lined Chipboard for Retail Facings
Virgin SBS provides superior print brightness, stiffness consistency, and crack-free scoring, whereas recycled board lowers initial cost but adds waste.
ISO 8791 PPS Roughness
PPS Smoothness Method
The standardized measurement of micro-geometric paper topography utilizes a Parker Print Surf instrument to quantify surface deviation under controlled clamping pressure. ISO 8791 PPS Roughness determines the mean air leakage between a spring-loaded metal measuring head and a moving paper web, yielding micrometers of deviation that directly predict ink transfer efficiency in high-speed rotary printing. This metric governs surface evaluation exclusively for uncoated and coated papers destined for offset and gravure printing, but fails to capture macro-level curl or structural caliper variations across a reel.
Converting plants apply the standard to verify that incoming stock meets smoothness thresholds required for uniform dot reproduction on coated paper grades.
Clamping Pressure Parameter
Air flow resistance depends directly on the chosen backing hardness and the applied load during the test procedure. Hard backing configurations simulate the rigid impression cylinder conditions found in offset presses, whereas soft backing settings mimic the resilient packing blankets used in letterpress equipment. Substrates react differently to these applied forces based on their internal fiber density and filler distribution.
High-speed printing requires paper deformation behavior to remain stable under rapid mechanical compression. Mills adjust calendering nip pressures to manipulate this compressibility index, balancing surface smoothness gains against permanent losses in paper bulk and opacity.
Ink Transfer Tolerance
Micro-cavities measured by pneumatic roughness meters dictate the minimum liquid film thickness needed to achieve complete halftone coverage across the sheet. Excessive air leakage channels fountain solution into valleys while starving adjacent image areas of pigment, causing speckle and broken lines in fine screens. Printers adjust lithographic ink tack and viscosity when handling rougher stocks to bridge surface voids without causing paper picking defects.
Surface uniformity limits govern the maximum allowable printing speed before ink starvation occurs at the trailing edge of solid blocks.