Capillary Sorption Anomalies under Dynamic Surface Tension Gradients in Recycled Paperboard Substrates
Dynamic surface tension gradients in recycled paperboard cause capillary stalling, uneven ink penetration, and severe converting spoilage.
ISO 3783 IGT Pick
Strength Measurement
Surface strength evaluation of paper and board determines the resistance of the substrate to picking or delamination during offset printing. The standard procedure, known as the iso 3783 igt pick test, measures the velocity at which the surface layer begins to rupture under a force applied by a specialized testing liquid. It helps board manufacturers identify weak points in the coating or the base sheet before the material reaches the press room.
Test Execution
A specialized apparatus accelerates a sector of paper against an inked wheel. In the iso 3783 igt pick method, the operator applies an oil of known viscosity to the printing wheel. The resulting print strip shows a start point of damage where the oil tack overcame the surface strength of the paper.
Press Suitability
High-speed offset presses generate substantial tack forces that can pull fibres or coating flakes off the paper surface. The values derived from the iso 3783 igt pick test allow printers to select inks with the appropriate tack level for a given paper grade. When the paper surface is too weak, debris accumulates on the offset blanket, causing print defects and necessitating frequent press stops for cleaning.
Modifying starch levels in the size press allows paper mills to adjust this resistance to meet the demanding requirements of commercial printing.